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Chapter 5 Environment And Its Resources Short Answer Questions

Question 1. Mention the percentage of nitrogen, oxygen, and carbon dioxide in the air.
Answer:
(1)’Nitrogen’ – 77.17%
(2)Oxygen – 20.60%
(3) Carbon di-oxide – 0.03%

Question 2. What is the Nitrogen Cycle?
Answer: The cyclic rotation of atmospheric nitrogen gas from the atmosphere to soil from soil to the living body and again from the living body to its source is called the nitrogen cycle.

Question 3. What is meant by nitrification?
Answer: The process of conversion of ammonia to nitrite (NO₂) and nitrite to nitrate (NO3) with the help of nitrifying bacteria (such as Nitrosomonas and Nitrobacter) is called nitrification.

Question 4. Mention the different components of an ecosystem.
Answer: There are two components of an ecosystem
(1)Abiotic Soil, water, minerals, air, temperature, light, humidity, etc.
(2)Biotic Producers, consumers, and demmposers.

Question 5. Name two abiotic and three biotic components of the ecosystem.
Answer:
(1) Abiotic:-
(1) soil and
(2) water.

(2) Biotic:-
(1) producers,
(2) consumers,
(3) decomposers.

Wbbse 10th Class Life Science Question Answer

Question 6. What do you understand by the term producer in the ecosystem?
Answer: The autotrophs (green plants) that can convert solar energy into potential chemical energy by the process of photosynthesis are called producers. ExampleMango trees.

Question 7. What is meant by Consumer?
Answer: The organisms that are unable to prepare their food by the process of photosynthesis and directly or indirectly depend on autotrophs for their food, are called consumers. Example Grasshopper, butterflies, toad, snake.

Question 8. Give the name of the denitrifying bacterium and mention its functions.
Answer:
(i) Bacillus denitrificance.
(ii) Function It converts nitrate and nitrite into free form of nitrogen. This also helps to return nitrogen to its source.

Question 9. What is Biomass?
Answer: The weight of all the organisms forming a given population in a given area is called biomass.

Question 10. What do you mean by plankton and nekton?
Answer: PlanktonThe free-floating microorganisms are called plankton.

For example algae and protozoa.
Nekton Swimming animals in the pelagic zone of the sea or lake are called nekton.

Example Fishes and whales.

Question 11. Arrange the following organisms in the correct sequence (from producer to secondary consumer): Kingfisher – Algae – Fish.
Answer: Algae – fish – kingfisher.

Question 12. Explain the food chain in the ecosystem.
Answer: The linear arrangement of living organisms in which one is the food of the other organism and the transfer of food energy occurs systematically is called a food chain. Example:- Grass – Grasshopper – Toad – Snake – peacock.

Question 13. What is meant by decomposer in an ecosystem?
Answer: The saprophytic organisms like bacteria and fungi which decompose the dead body of plants and animals, are called decomposers.

Question 14. Write the names of three organic and three inorganic components of an ecosystem.
Answer:
(1) Organic components –
(1)Carbohydrates,
(2) Proteins,
(3) Fats.

(2) Inorganic components –
(1) Water,
(2) Air,
(3) Minerals (Ca, Mg, Fe, etc.)

Question 15. Indicate with arrows the path of the flow of energy among toads, vultures, grass, snakes, and grasshoppers in a grassland ecosystem.
Answer: Grass > Grasshopper> Toad > Snake > Vulture.

Question 16. Write the difference between the Food chain and the Food web.
Answer:

Question 17. What is a food pyramid?
Answer: Food pyramid The gradual reduction of the trophic level of the food chain of an ecosystem producing a conical pyramid-like structure is called an ecological pyramid. Ex. pyramid of number, pyramid of mass, and pyramid of energy.

Question 18. What disaster would occur in a grassland ecosystem if the application of pesticides kills the decomposer bacteria and fungi The ecosystem will be unbalanced in the absence of decomposers. The dead bodies of plants and animals will be accumulated on the earth.

Question 19. Explain how biotic factors of an ecosystem are dependent on abiotic factors.
Answer: Producers, consumers, and decomposers are biotic factors. Consumers and decomposers obtain their food from producers directly or indirectly. Producers obtain water from the soil and air. These two are raw materials. Sunlight is obtained from the sun. They prepare their food by the process of photosynthesis. Thus biotic factors are dependent on abiotic.

Question 20. Mention the role of producers in an ecosystem.
Answer: Producers use solar energy to prepare their food. This food is the source of food for other living. They also produce oxygen gas. This gas is used by living for respiration.

Question 21. What is meant by conservation?
Answer: The process of proper utilization and management of natural resources (like air, water, soil, etc.) to keep their composition normal for the welfare of human beings is called conservation.

Question 22. Mention two main purposes of conservation.
Answer:
(1) To maintain the balance of ecosystem and
(2) to ensure a continuous yield of useful plants, animals, and materials by establishing a balanced cycle of harvest and renewal.

Wbbse 10th Class Life Science Question Answer

Question 23. What is meant by the conservation of soil?
Answer: To keep the normal balance of the components of soil which are essential for plant growth is called soil conservation.

Question 24. What is a National Park?
Answer: A national park is an area that is strictly reserved for the betterment of wildlife and where activities like forestry, grazing, and cultivation are not allowed. Ex – Kaziranga, Corbett, Gir, Kanha, etc.

Question 25. What do you mean by sanctuary?
Answer: A sanctuary is a protected area that is reserved for the conservation of only animals and human activities like harvesting of timber, and collection of minor forest products, and private ownership rights are allowed so long as they do not interfere with the wellbeing of animals. Ex-Jaldapara, Nagarjun sagar, Dachigam.

Question 26. What is a reserve forest or protected forest?
Answer: It is a forest area that is protected with all its components by the India Forest Act. Entrance without permission is prohibited. Ex-Gorumara, periyar.

Question 27. Mention any two causes of soil erosion.
Answer:
(1) Exposed dry soil without any vegetation.
(2)Overgrazing by cattle.

Question 28. Write two aims and objectives of conservation.
Answer:
(1) To maintain the ecological balance.
(2) To protect the endangered species.

Question 29. The population of deer in a particular forest land has suddenly and rapidly increased. What steps (any two) will you take to bring back a balance in the ecosystem after analyzing the possible causes of the increase in the population of deer?
Answer:
(1) Provide food and water as early as possible.
(2) The tree plantation scheme should be sped up.

Question 30. The biosphere is considered the largest biological system. Give reasons.
Answer: Because the biosphere has a structure made up of all the living and nonliving components of Earth where each component performs a certain function. Their functions make the biosphere dynamic and stable.

Question 31. A plant cannot absorb Nitrogen directly from the air.
Answer: Reasons
(1)Direct nitrogen-absorbing biological processes are absent in plants.
(2)Nitrogen gas is insoluble in water.
(3)Nitrogen is a comparatively less reactive gas.

Question 32. Why is the pyramid of energy always upright?
Answer: The pyramid of energy is always upright because the flow of energy always takes place from producer to consumer, which means in one direction only.

Wbbse 10th Class Life Science Question Answer

Question 33. Name two case studies in India for the food crisis.
Answer:
(1) Irish Famine (1851) induced by fungus Phytophthora – infestans causing late blight of potato.
(2) Great Bengal Famine (1942) induces by the fungus Dreschlera-oryzae causing the Brown spot disease of Rice.

Question 34. Why are windmills located in coastal areas?
Answer: Because the minimum wind velocity required to run a windmill is 20 km/hour, which is possible only in coastal areas.

Question 35. What is geothermal energy?
Answer: The energy obtained from the interior of the earth is called geothermal energy.

Question 36. What is biomass?
Answer: The matter contained in the body of plants and animals is called biomass. It is used to produce energy. It contributes 15% of total energy.

Question 37. What is Eutrophication?
Answer: Excess amounts of untreated sewage and pollutants are dumped into water bodies, accelerating the growth of algae and depleting O₂ content, result in damage to aquatic life and the water smells pungent.

Question 38. Define biomagnification.
Answer: The gradual increase of harmful chemicals like pesticides from one trophic level to another through a food chain is called biomagnification.

Question 39. What is global warming?
Answer: Due to the increase in CO₂ concentration in the atmosphere, the temperature of the earth increases causing the melting of glaciers and polar caps cap is called global warming.

Question 40. What are greenhouse gases?
Answer: The gases which cause the greenhouse effect are called greenhouse gases, eg. Methane, CO₂ water vapor, etc.

Question 41. Define ecology and environment.
Answer:
Ecology :
The natural surrounding of an organism, which affects its life, by directly influencing its activities, is called an environment. It includes both physical and living environments.

Environment:
The branch of science which deals with the interrelationship between the living organism and the environment is called ecology.

E. Flaeckel (1869) first proposed the term ecology.

Question 42. Mention the relationship between the food chain and the food web in the ecosystem.
Answer:
Food Chain :
The sequential process in which one organism consumes another to transfer food energy is called a food chain.

Food web:
The network of various food chains that are interconnected at various trophic levels is called the food web.
Relation: Many food chains of the same habitat form a food web. So, the food chain is a structural and functional unit of the food web. In a food web food chains are interconnected and interdependent.

Question 43. Define two types of ecology.
Answer:
Autecology:
The study of an individual organism or individual species and its interaction with the environment.

Synecology :
The study of a group of organisms or living communities and their interrelationship with the environment.

Question 44. What is meant by nitrogen fixation? Mention the role of symbiotic bacteria in that process.
Answer:
(1) Nitrogen fixation The conversion of atmospheric free nitrogen gas into the form of nitrite (NO₂) and nitrate (NO₃) is called nitrogen fixation.
It takes place in three ways –
(1) Natural fixation,
(2) Biological fixation,
(3) Chemical fixation.

Wbbse 10th Class Life Science Question Answer

(2) Role of symbiotic bacteria in nitrogen fixation Rhizobium bacteria lives in the root nodules of leguminous plants like peas and grams. It converts nitrogen into ammonia in the presence of the enzyme ‘ nitrogenase’. Further, this ammonia is utilized by plants to produce their nitrogenous substances.

N₂ + 3H2 = 2NH₃

Question 45. Discuss in brief the role of free-living and symbiotic bacteria in the fixation of free nitrogen in the soil.
Answer:
(1) Role of free-living bacteria Some saprophytic bacteria live freely in soil and convert free nitrogen into nitrite and nitrate, for example – Azotobacter and Clostridium.
(2) Role of symbiotic bacteria They live in the root nodules of leguminous plants i.e., peas and grams. They convert nitrogen into ammonia in the presence of the enzyme nitrogenase. This ammonia is used to form nitrogenous compounds by the plant.

Question 46. Discuss two important roles of organisms in supplying carbon dioxide to the environment.
Answer: Role of organisms in supplying carbon-di-oxide to the environment –
(1)Respiration Every living organism releases carbon dioxide into the environment during respiration.
(2)DecompositionThe dead bodies of organisms are decomposed by saprophytic bacteria and fungi. The carbon dioxide gas produced during decomposition is returned to the environment.
(3)Burning Carbon dioxide gas returns to the environment due to the burning of different types of fuels, such as coal, petrol, diesel, etc.

Question 47. Explain in brief how energy flows through the living components of the ecosystem.
Answer: The way energy flows in the living components of the ecosystem
(1)Solar energy is the only source of energy flow.
(2)Only producers can transform the solar energy into chemical energy. This chemical energy is stored within food. Solar energy never goes back to the sun from the producer. Primary consumers get their energy from producers and this energy also never goes back to the producers.

In the same way, secondary consumers obtain energy from primary consumers and tertiary consumers get energy from secondary consumers. After the death of producers and consumers, decomposers decompose the dead bodies and obtain energy.
(3) There is a gradual decrease in the energy flow from the beginning to the end of a food chain.

Question 48. What do you mean by reserve forest? Name a reserve forest in West Bengal.
Answer: It is a forest area that is protected with all its components by the India Forest Act. Entrance without permission is prohibited. Ex – Gorumara, periyar.

Question 49. Mention any three ways of water conservation.
Answer: Methods of water conservation
(1)By preventing excess cutting of trees and promoting the practice of excess tree plantation.
(2)By treating sewage and industrial wastes in water treatment plants before releasing them into rivers.
(3)By constructing dams and bunds.

Question 50. Mention in brief the importance of wildlife conservation.
Answer: The importance of wildlife conservation.
(1) Wildlife (plants and animals) maintains the continuity of the ecosystem of nature through the balance of population and food chains.
(2)They keep our environment clean, for example, green plants and scavenger birds.
(3)They are a source of various medicines.
(4)They help to understand the mechanism of evolution.
(5)They are a source of foreign currency, for example, visiting national parks by foreigners.

Question 51. What are decomposers? What role is played by it in an ecosystem?
Answer: Decomposes are also called reducers. The organism gets its nutrients from dead organisms and decaying organic matter, eg. Bacteria, and fungi.

Decomposers and transformers return the chemical nutrients to nature by decomposing and reducing the dead bodies, then these nutrients can be reused by the producers. It takes an important role in recycling the chemical nutrients, which also maintain the balance of the ecosystem.

Question 52. What is the nutrient cycle?
Answer: The cyclic movement of the chemical elements, i.e. nutrient cycling of the biosphere between the living organism to the environment is called the Bio-geo-chemical cycle.

These are the gaseous cycles (Carbon and Oxygen cycle)
Sedimentary cycle (Sulphur & Phosphorus)
Hydrological cycle (Water cycle)

Substances such as oxygen, carbon dioxide, water, and minerals are constantly absorbed by organisms, but as soon as these substances are lost from the physical world, they are replaced by natural processes and balance the ecosystem.

Chapter 5 Environment And Its Resources Descriptive Type Questions And Answers

Question 1. What are the impacts of environmental factors on an organism at the individual level?
Answer:
(1) Light:
The productivity of food in green plants depends on light. Trees are more productive than submerged plants.

Photoperiodism is the phenomenon in which flowering and seed germination depend on the duration of light. Plants are long-day plants (pea, radish), short-day plants(dahlia, Sugarcane), and day-neutral plants (cotton, tomato).

The intensity and color of light also control the process of photosynthesis. Light enhances the pigmentation of skin for many animals too, light is important in what they use.

(2)Temperature:
The plants of tropical regions have a greater number of stomata to regulate temperature. The plants in temperate regions have spiny leaves to reduce the damage caused by frost. Temperature affects the genetics of enzymes and through it the basal metabolism, activity, and other physiological functions of the organism.

A few organisms can tolerate and thrive in a wide range of temperatures. (Eurythermal), but a vast majority of them are restricted to a narrow range of temperatures (Stenothermal).

In some animals body temperature varies with environmental temp, Called poikilo thermic animals (cold-blooded).
Eg fishes, amphibians, and reptiles.

Some animals maintain constant body temperature in any environment, called warm-blooded animals (Homeothermic animals).
Eg birds and mammals.

(3)Humidity:
Animals living in desert regions have few sweat glands and excrete urine very less. Plants growing in arid climates develop features that resist atmospheric dryness. They have less and sunken stomata, waxy leaves, developed tap roof system.

Question 2. What is the impact of environmental factors on an organism at the population level?
Answer: A group of individuals of the same species inhabiting a particular geographic area at a given period is called a population.

The total number of species in a specific natural habitat is called population density.
The population density changes by change in four basic processes, two of which contribute to an increase and two to a decrease in population –

(1)Natality:
Refers to several births during a given period in the population that are added to initial density.

(2)Mortality :
Mortality is the number of deaths in the population during a given period.

(3)Immigration :
Immigration is the number of individuals of the same species that have come into the habitat from elsewhere during the period under consideration.

(4)Emigration:
Emigration is the number of individuals in the population who left the habitat and lived elsewhere during the period under consideration.

If N is the population density at time (t) then its density at time (t + l)is –
Nt+1 = Nt+ [(B + I)-(D + E)]

Question 3. Explain the interaction among the population at the community level.
Answer: There is no such habitat and such a situation is even inconceivable. For any species, the minimal requirement is one more species on which it can feed.

Even a plant species, which makes it our food, can not survive alone. It needs soil microbes to break down the organic matter in the soil and return the inorganic nutrients for absorption. This is called interaction in population.
Population interaction

1. Symbiosis or Mutualism:
It is an interspecific co-operation in which two species live in a physically close association and both are benefited by each other.
Eg. Lichen is the association of algae and fungi. Nitrogen-fixing bacteria in nodules of Leguminous plants.

Competition :
Interaction is where members of the same or other species compete with each other to acquire, food, shelter, and water. It may be inter-specific or intra-specific. In the competition process, the fitness of one species is significantly lower in the presence of another species.
Eg. weeds in crop fields compete for food and shelter with crops and finally reduce the productivity of crops.

Predation:
In this type of interaction one species attacks (Predator) another species (Prey) to kill and consume it. The predator obtains nutrients and energy from the prey. The predator keeps the prey population under control.

Biological control methods adopted in agricultural pest control are based on the ability of the predator to regulate the prey population. But if a predator is too efficient and over-exploits its prey, then the prey might become extinct, and following it, the predator will also become extinct for lack of food.

Parasitism:
The interaction in which the parasite gets the benefit and the host gets the loss. Parasite may be –

Ectoparasites – draw nutrients from the outside body of the host.
eg. Female anopheles mosquito, Leech, bedbugs.

Endoparasites – live inside the body of the host and collect nutrients from them.
Eg. – Tapeworm, Ascaris.

Obligatory parasites – the organism leading parasitic life throughout its life cycle.
Eg. Tapeworm, Ascaris.

Facultative parasites – organisms show parasitic behavior in certain periods of their life cycle.
eg. Female anopheles mosquito.

Commensalism :
This is the interaction in which one species benefits and the other is neither harmed nor benefited.
Eg. (1) an orchid growing as an epiphyte on a mango branch and
(2) barnacles growing on the back of the whale benefited while neither the mango tree nor the whale derived any apparent benefit.

Question 4. Explain the interaction between organism and their organizations at the ecosystem level.
Answer: Functional interrelation between biotic communities and their habitat constitutes an ecosystem.
There are two aspects of the ecosystem.
(1)Structural aspects-

Light – Source of energy of the living world.

Temperature – In the optimum temperature life process functions smoothly. Water – It influences the life of organisms. Aquatic organisms depend on water for their survival.

Atmosphere – The atmospheric pressure varies inversely with the altitude. Lower atmospheric pressure of oxygen and this condition is harmful.

Topography – The altitude, landscape, the amount of light falling on a place or wind blowing add to form the topographic factors of an ecosystem.

Question 5. Difference between food chain and food web.
Answer:

Question 6. What is an ecosystem? Mention the different components of an ecosystem. Briefly describe the role of abiotic and biotic factors which control an ecosystem.
Answer:
Ecosystem :
The basic structural and functional unit of ecology is called an ecosystem.

Components of Ecosystem :
There are two components of the ecosystem –
1. Abiotic,
2. Biotic

1. Abiotic – The non-living constituents of the environment are called abiotic.

Abiotic constituents are divided into three groups :
(1)Inorganic material –
This consists of water, soil, minerals (Ca, K, Mg, Fe, etc.), and gases like oxygen, Carbon dioxide, and nitrogen.

(2)Organic material –
Carbohydrates, proteins, and Fats of dead. organisms constitute the organic material.

(3)Climatic factors –
Rainfall, temperature, light, and humidity are climatic factors.

The principal climatic factor is light (solar energy). This energy is trapped by green plants during photosynthesis and stored as chemical energy in Carbohydrates.

2. Biotic – All the living organisms (plants and animals) of the environment are called biotic.

Biotics are classified into three groups –
(1)Producers,
(2) Consumers,
(3) Decomposers.

(1)Producers:- Green plants and photosynthetic bacteria that can prepare their food by the process of photosynthesis in the presence of sunlight are called producers.
(2)Consumers:- The heterotrophic organisms mostly animals which can not prepare their food by the process of photosynthesis and get it from other organisms, are called consumers.

There are three types of consumers –
(1) Primary consumers – The herbivores that directly eat the plant are called primary consumers.
Ex – goat, rabbit, deer, etc.

(2)Secondary consumers – The animals that eat herbivorous animals are called secondary consumers.
Ex-Fox, fish crow, snake, etc.
(3)Tertiary consumers – The animals that are not eaten by other animals are called tertiary consumers.
Ex – Hawk, owl, vulture, shark, tiger, lion, etc.

(3)Decomposers:- The saprophytic organisms that can decompose the organic materials of dead bodies of living organisms into simple inorganic materials are called decomposers.
Ex – Saprophytic bacteria and fungi.

Question 7. What is a food chain? Name the different types of food chains. Define them.
Answer:
(1) The arrangement of living organisms in which food energy passes from producer to consumer in a linear sequence of eat and be eaten is called a food chain.

(2) Types of food chain :
There are three types of food chains –
(1)Grazing food chain,
(2) Detritus food chain,
(3) Parasitic food chain.

(1)Grazing food chain :
The food chain that starts from producers and passes through consumers like primary, and secondary, and terminates with top consumers is called a grazing food chain.
Grasses -> insects -> Amphibians snakes -» peacock.

(2)Detritus food chain –
The food chain starts from dead organic matter, goes into microorganisms, and then to detritus-feeding organisms (detrivores) and their predators is called detritus food chain.
Dead organic matter -» microorganism -» small fish -> large fish.

(3)Parasitic food chain –
This chain passes from larger animals to smaller animals.
Plant -> Man -» Eschertia coli.

Question 8. What is an ecosystem? Explain what is meant by energy flow in an ecosystem.
Answer:
(1) The basic structural and functional unit of ecology is called an ecosystem.
(2) Energy flow in an ecosystem:-
In an ecosystem sun is the main source of energy. In the sun hydrogen is constantly transformed to helium with the release of an enormous amount of energy. This energy leaves the sun and passes into outer space in the form of light and other radiations.

Only a very small amount (0.1% of the total energy falling on earth) of light energy is absorbed by green plants and utilized in the formation of food. The radiant energy of the sun is transformed into chemical energy during photosynthesis. This chemical energy is stored within food (glucose).

Primary consumers feed on producers and thereby get the potential energy of producers. The secondary consumers feed on primary consumers, from where they get their potential energy. Similarly, tertiary consumers get their potential energy from secondary consumers.

The transfer of food energy from producers to various types of consumers is called a food chain.
A large part of energy is lost as heat at each transfer of energy; only a small amount of energy is converted into biomass.

Nature of energy flow in an ecosystem
(1)Solar energy is the only source of energy flow.
(2)Energy flow is unidirectional –
The green plants utilize light energy to prepare their food. This light energy never goes back to the sun. Primary consumers get their energy from the green plants and this energy never goes back to the green plants. The same thing happens with secondary consumers and tertiary consumers.

After the death of plants and animals, decomposers decompose the dead bodies. Heat energy is liberated during decomposition. This heat energy can not be utilized by green plants and animals.

(3) Gradual decrease in the energy flow – There is a gradual decrease in the energy flow from the beginning to the end of a food chain. The primary consumers do not get all the energy obtained by the producers. A part of energy is used by the producers, another part of the energy is lost and the remaining part of the energy is stored.

Question 9. (1) Discuss the role of organisms in the removal of free carbon dioxide from the environment, (2) What is meant by nitrification? Discuss the role of bacteria in this process.
Answer:
(1) Role of organism:-
Terrestrial green plants use free carbon di-oxide of air and aquatic submerged green plants use carbon di-oxide gas which is dissolved in the water for the process of photosynthesis. Some chemosynthetic bacteria, i.e., nitrosomonas also remove free carbon dioxide from the atmosphere for the preparation of their food.
(2)Nitrification:-
The process of conversion of ammonia into nitrite and nitrite into nitrate with the help of bacteria like Nitrosomonas and Nitrobacter respectively is called nitrification.

Question 10. Discuss the significance of cyclic rotation of elements like carbon, oxygen, and nitrogen in the environment.
Answer: Significance of cyclic rotation of carbon, oxygen, and nitrogen in the environment

Importance of carbon cycle:-
(1)Carbon is an important element of organic compounds.
(2)Its simple form C02gas is a raw material for photosynthesis by which green plants prepare their foods in the form of glucose.
(3)It helps in the formation of protoplasm which is a living material,
(4)It maintains the balance of carbon in its source.

Importance of Oxygen cycle:-
(1)It is necessary for respiration.
(2)It helps living to continue their life in this universe, otherwise, in the absence of this process, the universe will become lifeless.
(3)It takes part in the formation of living material, protoplasm.
(4)We cannot imagine a living world in the absence of oxygen.
(5)It helps in combustion.
(6)The cycle of oxygen is essential for different types of organic and inorganic chemical reactions.
(7)This cycle keeps the composition of air fixed/constant.

Importance of nitrogen cycle:-
(1)Nitrogen is an essential element of some important substances like protoplasm, protein, enzymes hormones, etc.
(2)It takes part in the formation of cells, tissue, and organs.
(3)This cycle maintains the balance of nitrogen between living and non-living worlds.

Question 11. What is the main source of nitrogen in higher plants ordinarily? Where do the animals obtain this element? Mention the role of bacteria in the nitrogen cycle.
Answer:
(1) Main source of nitrogen:-
The water soluble nitrogenous compounds present within soil which are formed by the process of fixation are the source of nitrogen in higher plants.
(2)Animals obtain nitrogen from their food (ex. protein)
(3)Role of bacteria in the nitrogen cycle:-
Bacteria take an active part in the completion of the nitrogen cycle.

Different types of bacteria are involved in different stages.
(1)Fixation of atmospheric nitrogen:-
Nitrogen-fixing bacteria convert atmospheric nitrogen gas into nitrite and nitrate such as
Symbiotic bacteria — Rhizobium leguminosorium.
Free-living bacteria – Azotobacter, Clostridium.
(2)Ammonification:-
The ammonifying bacteria convert amino acids into ammonia.
Example – Bacillus-ramosus, Bacillus vulgaris.
(3)Nitrification:-
Nitrosofying bacteria convert ammonia to nitrite and nitrifying bacteria convert nitrite to nitrate.
Example – Nitrosomonas, Nitrobacter.
(4)Denitrification :-
Denitrifying bacteria convert nitrite and nitrate into free atmospheric nitrogen gas. Example – Bacillus suletilis, Bacillus denitrificans.

Question 12. Name the gas which is essential for plants but cannot be absorbed directly from the air. What is the normal percentage of that gas in the air? With the help of a diagram, briefly describe the cycle of the said gas.
Answer:
(1) Name of the gas:- Nitrogen.
(2) The normal percentage of nitrogen gas in atmospheric air is 77.17%.
(3)Process of nitrogen cycle:- The cycle of nitrogen gas is completed in the following stages

(1) Fixation of atmospheric nitrogen:-
The process of conversion of free nitrogen into nitrite and nitrate is called fixation.
This process occurs by three methods –
(1) Natural method,
(2) Chemical method,
(3) Biological method.

(1)Natural Method:-
Nitrogen gas reacts with oxygen gas to produce nitric oxide during electric discharge in the atmosphere. The electric discharge provides energy which is necessary for the reaction. Nitric oxide reacts with oxygen gas to produce nitrogen dioxide. This oxide reacts with rainwater and forms nitrous and nitric acid. These acids react with oxides of metals present in the soil to form their nitrite and nitrate respectively.
N₂ + O₂ = 2NO
2NO + O₂ = 2NO₂
2NO₂ + H₂O = HNO₂ + HNO3
CaO + 2HNO₂ = Ca(NO₂)₂ + H₂O
CaO + 2HNO₃ = Ca(NO₃)₂ + H₂O

(2)Chemical Method:-
In the laboratory nitrogen gas is allowed to react with hydrogen gas to produce ammonia in the presence of iron powder which acts as a catalyst. Now ammonia reacts with carbon dioxide gas to produce urea.
N₂ + 3H₂ = 2NH₃
2NH₃ + CO₂ = (NH2)2CO + H₂O

(3)Biological Method:-
Some bacteria and algae are capable of fixing atmospheric nitrogen.

Nitrogen fixation by bacteria:-
By symbiotic bacteria:-
Rhizobium lives in the root nodules of leguminous plants like peas and gram and converts nitrogen into nitrite and nitrate. Plants use this nitrite and nitrate. Rhizobium takes glucose from the host.

By saprophytic bacteria:-
Azotobacter and Clostridium are present in soil. They convert nitrogen into nitrite and nitrate within their body. Nitrite and nitrate present in their body mix in soil after their death.

By autophytic bacteria:-
Rhodomicrobium (colored) and desulphuricans (colorless) are anaerobic and autophytic. They convert nitrogen into nitrite and nitrate.

Nitrogen fixation by algae:-
Some algae (Nostoc, Anabaena, and Calothrix) convert atmospheric free nitrogen into nitrite and nitrate.

(2)Absorption of fixed nitrogen:-
The nitrite and nitrate forms of compounds produced by the process of fixation are soluble in water. They enter into the cavity of root hairs and finally into the plant cells through absorption.

(3)Assimilation of absorbed nitrogen:-
The nitrogenous compounds are now assimilated by metabolic reactions. Various complex nitrogenous organic compounds like proteins, hormones, enzymes, etc. are formed within the plant body. Animals get nitrogen from the plant. The process of assimilation of plant nitrogenous compounds takes place in the animal body, due to which animal complex nitrogenous organic compounds are formed.

(5)Ammonification:-
Production of ammonia due to the decomposition of complex organic nitrogenous compounds present within the dead bodies of plants and animals with the help of ammonifying bacteria like Bacillus vulgaris and Bacillus ramosus is called ammonification.
Protein – Amino acid, Amino Acid – Ammonia (NH3).

(6)Nitrification:-
The conversion of ammonia into nitrite and nitrate with the help of nitrifying bacteria is called nitrification.
2NH₃ + 3O₂ = 2HNO₂ + 2H₂O + 1,30,000 K. cal. (Nitrosomanas)
2HNO₂ + 02 = 2HNO3 + 35,000 K. cal. (Nitrobacter)

(7)Denitrification :-
The conversion of nitrite and nitrate present within the soil to free nitrogen gas with the help of denitrifying bacteria like Bacillus denitrificans is called denitrification.
5S + 6KNO₃ + 2CaCO₃ = 2K₂SO₄ + 2CaSO₄ + 2CO₂ + 2N₂ + 6,60,000 cal.

Question 13. Discuss the interrelationship among the different components of the system.
Answer: There are two main components of an ecosystem in
(1) abiotic and
(2) biotic.
Soil, minerals, water, gases, temperature, light, etc. collectively constitute the abiotic part of the ecosystem. Livings like producers, consumers, and decomposers form the biotic part of the ecosystem. Green plants convert solar energy into chemical energy during photosynthesis.

Plants take carbon dioxide and water from their outer sources for photosynthesis and form glucose as food. Oxygen gas is also liberated during this process. Heterophytic plants and all animals obtain their food from the plants. Here animals are called consumers.

Decomposers decompose the dead bodies of producers and consumers by secreting enzymes. Thus they help to return the materials to their respective sources.

There is a cyclic rotation of materials occurring in an active ecosystem and the flow of energy is unidirectional. The energy flows from producer to consumer.

Question 14. Discuss the importance of the carbon cycle, nitrogen cycle, and nitrogen cycle.
Answer: Importance of carbon cycle:-
(1)Carbon is an important element of organic compounds.
(2)Its simple form CO₂ gas is a raw material for photosynthesis by which green plants prepare their foods in the form of glucose.
(3)It helps, in the formation of protoplasm which is a living material.
(4)It maintains the balance of carbon in its source.

Importance of nitrogen cycle:-
(1)Nitrogen is an essential element of some important substances like protoplasm, protein, enzymes hormones, etc.
(2)It takes part in the formation of cells, tissues, and organs.
(3)This cycle maintains the balance of nitrogen between living and non-living worlds.

Importance of bacteria in the nitrogen cycle:-
(1)They convert atmospheric nitrogen in the form of NO₂ and NO3 so that they can be absorbed by plants,
for example:- Rhizobium.
(2)They decompose the dead bodies of living organisms and change protein into ammonia, for example:- Bacillus vulgaris.
(3)They convert ammonia into nitrite, for example Nitrosomonas.
(4)They convert nitrite into nitrate, for example:- Nitrobacter.
(5)They convert nitrite and nitrate into free nitrogen, for example:- Bacillus denitrificans.

Question 15. Discuss the importance of Tiger conservation, purpose of conservation, soil conservation, water conservation
Answer: Importance of Tiger conservation:-
(1) The tiger helps in balancing the forest ecosystem.
(2)They are conserved in national parks and zoos for the collection of foreign money.
(3)They are also conserved for recreation, for example:- circus.

Importance of purpose of conservation:-
(1)To keep the environment clean and balanced.
(2)To balance and maintain the continuity of the ecosystem.
(3)To store the nutrients and other necessities in proper quantity.
(4)To protect the living organisms from diseases.
(5)To save the living organisms from disappearance from this universe

Importance of soil conservation:-
(1)To keep the macro and micro essential elements in proper quantity.
(2)To increase the fertility of the soil.
(3)To supply nutrients to the plants for their proper growth.
(4)For the survival of the living organism, i.e., plants depend directly and animals depend indirectly on soil.

Question 16. Discuss the importance of water conservation & forest conservation.
Answer: Importance of water conservation:-
(1)To protect living organisms from various diseases.
(2)To maintain the balance of the aquatic ecosystem.
(3)To keep water fresh and clean.
(4)To maintain the stock of water for future use.
(5)To provide a safe environment for the survival of aquatic life.

Importance of forest conservation:-
(1)To save the habitat of wild animals.
(2)To balance the forest ecosystem.
(3)For the continuity of the bio-geochemical cycle.
(4)To obtain useful substances i.e., medicine, latex, food, cloth, etc.
(5)To obtain timber for various functions such as doors, windows, tables, chairs, etc.
(6)To check soil erosion.
(7)To increase rainfall.
(8)To purify atmospheric air.
(9)To maintain the balance of O₂ and CO₂ in the atmosphere.

Question 17. Name a gas that can be directly absorbed by the plants from the air but cannot be absorbed directly by the animals. What is the normal percentage of that gas in the air? With the help of a diagram briefly describe the cycle of the said gas.
Answer:
(1) Name of the gas – Carbon dioxide.
(2)Normal percentage of carbon dioxide gas in air is 0.03% to 0.04%.
(3)Methods of carbon dioxide gas cycle The cycle of carbon dioxide gas is completed in the following three stages –
(1) Removal of carbon dioxide gas from its source,
(2) Assimilation of carbon dioxide gas,
(3) Returning of carbon dioxide gas to its source.

(1)Removal of carbon dioxide gas from its source:-
The autotrophs (green plants) intake carbon dioxide from their source to perform the process of photosynthesis.

(2)Assimilation of carbon dioxide gas:-
The carbon dioxide gas which is taken from the environment by autotrophic organisms is assimilated into complex organic molecules like glucose. The green plants can fix 4.9 x 1012 kg of carbon per year. The heterophytes and animals get their required carbon from the autotrophs.

(3)Returning of carbon dioxide gas to its source:-
The carbon dioxide gas returns to its source by the following methods
(1)Respiration:-
Every living organism performs the process of respiration to obtain energy. The carbon dioxide gas produced during respiration is returned to its source.
(2)Combustion:-
The carbon dioxide gas produced due to the burning of different types of fuels is returned to its source.
(3)Decomposition:-
The dead bodies of various plants and animals are decomposed by the action of decomposers. Carbon dioxide produced during decomposition due to their respiratory activity is returned to its source.
(4)Evaporation:-
The carbon dioxide gas which is dissolved in different sources of water returns to its source during the evaporation of water from these sources.

Question 18. Discuss briefly the role of Bacteria in releasing and fixing nitrogen in the environment.
Answer: Role of Bacteria in releasing and fixing nitrogen in the environment:
Nitrogen is the most important constituent of the protoplasm of the living organism. Though the atmosphere contains as much as 77.17% elementary nitrogen, most living organisms cannot utilize this gaseous nitrogen to synthesize their protein. Some bacteria are capable of fixing the atmospheric nitrogen.

Some free-living bacteria like Clostridium, azotobacter, etc. can fix atmospheric nitrogen into nitrogenous compounds.

Symbiotic bacteria like Rhizobium live in the root nodules of leguminous plants and some symbiotic bacteria like Casuarina live in the root nodules of nonleguminous plants and can fix atmospheric nitrogen.

Some ammonifying bacteria like Bacillus ramosus, Bacillus vulgaris, etc. release ammonia from the protein of dead organisms.

Some nitrifying bacteria convert ammonia into nitrite ions. Nitrosomonas converts ammonium ions into nitrite ions and Nitrobacter converts nitrite into nitrate ions.

Some denitrifying bacteria like Bacillus denitrificans, pseudomonas, etc. convert nitrite and nitrate into atmospheric free nitrogen.

Question 19. What is the source of oxygen in atmospheric air? What is meant by ‘oxygen cycle? Describe the oxygen cycle in nature with the help of a line drawing.
Answer:
(1) Source of oxygen:-
Green plants supply oxygen gas to the atmosphere during the process of photosynthesis.
(2)Oxygen cycle:-
The process by which oxygen from its source enters into the living body, takes part in metabolic reaction, and in the last, returns to its source, is called the oxygen cycle.
(3)Methods of oxygen cycle:-
The cycle of oxygen is completed in three stages

(1)Removal of oxygen from its source:-
Respiration Every living organism takes in oxygen gas for respiration.
Combustion Some quantity of oxygen is utilized during the burning of different fuels.

(2)Taking part in metabolic reaction:-
Carbon dioxide and water are produced during respiration. Carbon dioxide comes out to the atmosphere but the oxygen atom present in water is assimilated to form complex organic molecules.

(3)Returning of oxygen to its source:-
Green plants produce oxygen gas during the process of photosynthesis. This gas comes out through the stomata of the leaves and is mixed with atmospheric air.

Question 20. What is an ecosystem? Explain the interrelationship among the different components of the ecosystem.
Answer:
(1) Ecosystem :
The basic structural and functional unit of ecology is called an ecosystem.
(2)Inter-relationship among the components of ecosystem :
There are two main components of an ecosystem in
(1) abiotic and
(2) biotic.

Soil, minerals, water, gases, temperature, light, etc. collectively constitute the abiotic part of the ecosystem. Living beings like, producers, consumers, and decomposers form a biotic part of the ecosystem. Green plants convert solar energy into chemical energy during photosynthesis. Plants take carbon dioxide and water from their outer sources for photosynthesis and form glucose as food.

Oxygen gas is also liberated during this process. Heterophytic plants and all animals obtain their food from the plants. Here animals are called consumers. Decomposers decompose the dead bodies of producers and consumers by secreting enzymes. Thus they help to return the materials to their respective sources.

There is a cyclic rotation of materials that occurs in an active ecosystem and the flow of energy is unidirectional. The energy flows from producer to consumer.

Question 21. What do you mean by water conservation? Mention the means of conservation of water.
Answer:
(1) Water conservation:-
The use of the proper quantity of water and to prevent the addition of harmful substances into its sources is called water conservation.

(2)Methods of water conservation:-
(1)By preventing excess cutting of trees and promoting the practice of excess tree plantation.
(2)By treating sewage and industrial wastes in water treatment plants before releasing them into rivers.
(3)By constructing dams and bunds.
(4)By preventing washing, bathing, and cleaning of animals in pond water.
(5)By forbidding testing of bombs in oceans.
(6)By checking active sedimentation in lakes, ponds, rivers, etc.
(7)By controlling the use of pesticides and insecticides.

Question 22. What do you mean by forest conservation? Mention the means of forest conservation.
Answer:
(1) Forest conservation :
To control the excessive cutting of trees for timber and set of industries and to protect it from fire and disease is called forest conservation.

(2)Means of conservation of forest:-
(1)By cutting down only matured trees.
(2)By promoting the practice of regular plantation of new sampling at specific distances.
(3)By preventing forest fires.
(4)To restrict the entrance of domestic animals.
(5)By implementing the laws formulated by the state and central government.
(6) Through mass awareness programs, people should be informed about the dangerous effects of deforestation.
(7)By protecting them from diseases and pests.
(8)By checking block cutting.

Question 23. Discuss in brief the means of conservation of tigers.
Answer: Means of conservation of tiger:-
(1)By promulgating the laws for unnecessary killing of tigers. A person violating the law is liable to legal action.
(2)To establish National Parks, sanctuaries, Protected areas, and Reserve forests in the different parts of the country.
(3)Educate the public so that they can understand the importance of tigers in this universe. For this lectures based on the importance of tigers should be arranged in universities, colleges, and schools. To develop mass consciousness cinema shows should be arranged. Print media also may be helpful in this program.

Question 24. What are the meanings of the terms Sanctuary and Reserve Forest? Give one example of a Sanctuary in West Bengal. Mention the importance of those forests.
Answer:
(1) Sanctuary:-
A sanctuary is a protected area that is reserved for the conservation of only animals and human activities like harvesting of timbre, and collection of minor forest products, and private ownership rights are allowed so long as they do not interfere with the well-being of animals. Ex-Jaldapara, Nagarjuna sagar, Dachigam.

Reserve forest:-
It is a forest area that is protected with all its components by the India Forest Act. Entrance without permission is prohibited. Ex – Gorumara, periyar.

(2)Sanctuary in West Bengal — Jaldapara
(3)Importance of Reserve forest
(1)To save the habitat of wild animals.
(2)To balance the forest ecosystem.
(3)For the continuity of the bio-geochemical cycle.
(4)To obtain useful substances, i.e., medicine, latex, food, cloth, etc.
(5)To obtain timber for various functions such as doors, windows, tables, chairs, etc.
(6)To check soil erosion.
(7)To increase rainfall.
(8)To purify atmospheric air.

To maintain the balance of 02 and C02 in the atmosphere.

Question 25. Why is the replenishment of forests necessary? Or, What is the importance of forests in human life?
Answer: Forest is an important natural resource that provides us with many valuable things:
(1) Atmospheric regulation:
Forest regulates 02 and CO₂ balance. The CO₂ content in the atmosphere is taken up by the plants during photosynthesis and O₂ is released. This O₂ is used by the living organisms in the process of respiration.

(2)Control soil erosion :
The branches of roots firmly bind the soil particles with the ground. The dense leaves of forests prevent raindrops from hitting the soil rich in organic matter is porous and permeable and serves as a natural filtering agent. The humus increases the adhering capacity of the soil particles and prevents soil erosion.

(3)Productive use:
Forests provide several products such as timber, fruits, seeds, cloth, furniture, medicine, building materials, papers, and one of the important sources of economy.

(4)Local use :
People living in nearby villages collect firewood from the forest. They also collect honey, timber, cotton, fur, wool, and meat and market it for money. Medicinal plants, gums, and resins were also collected from the forest.

(5)Watershed protection :
Forests help to protect an area of land that separates water flowing to different rivers or seas.

Question 26. Write the important functions of the forest.
Answer:
(1) It maintains the ratio of O₂ and CO₂.
(2)It provides a natural habitat for wildlife plants and animals.
(3)In maintains climatic conditions by rainfall.
(4)It prevents soil erosion.
(5)It is an important source of building materials.
(6)It is used by local inhabitants for different purposes involving food and shelter.
(7)It provides medicines, spices, honey, clothes, paper, furniture, and other useful substances.

Question 27. Name the major types of forest in the world.
Answer:
(1) Tropical rain forest
(2)Sub-tropical forest
(3)Mediterranean forest
(4)Temperate forest
(5)Coniferous forest
(6)Plantation forest

Question 28. What are the causes of deforestation?
Answer:
(1) Population explosion
(2)Uncontrolled cutting of trees
(3)Development of road and railways
(4)Forest fires destroy trees and animal life
(5)Destruction of timber-yielding trees by fungal infection and by pest
(6) A water reservoir (dam) constructed across the stream used for generating power.
(7) Over-exploitation of land resources.
(8) Transformation of tropical rainforest to grassland.
(9)Forests are damaged by storms and snow.

Question 29. What are the consequences of deforestation?
Answer:
(1) Global warming – due to deforestation, the concentration of greenhouse gases (CO₂) increases in the atmosphere causing global warming.
(2)Decrease in groundwater level
(3)Change in soil character and erosion
(4)Wildlife extinction – forest is a natural habitat for millions of flora and fauna. Deforestation makes them homeless.
(5)Frequent floods and droughts destroy large numbers of trees.
(6)C02 consumption and oxygen production are affected adversely.
(7)Change in climatic conditions by affecting rain.
(8) Decrease in the quality and quantity of timber.
(9)Deterioration in the quality of life of the weaker section of people living in the forest.
(10)Increasing incidents of landslides.

Question 30. Define Afforestation. Write the importance of water on earth.
Answer: Process of planting trees in an area of land to form a forest. It increases the protective and productive outputs.

Water is a vital natural resource used for various purposes.
(1)Drinking purpose:
Water that is fit for drinking is called potable water and it is essential for all living organisms.

(2)Agriculture:
Plants need water to synthesize their food. A large quantity of water is used for the irrigation of crop fields.

(3)Industry:
Water is used as raw material, solvent, and washing medium in industry. The industry is very dependent on adequate water supplies. Major water users are steel, paper, textile, chemical, and petroleum refining and they account for nearly 80 percent of industrial water demand.

Question 31. Write the uses of water for different purposes.
Answer:
(1) Used in agriculture for irrigation of crops.
(2)Used for cooking, washing, bathing, cleaning, etc.
(3)Used in chemical laboratories as solvent.
(4)Used for performing various chemical reactions.
(5)Used in textile and paper industry.
(6)Water can dissolve gases like O₂ and oxygen.
(7)Used in photography.
(8) Water is used in biochemical reactions and enzymatic activities.
(9)Water is used to generate electricity in hydroelectric plants.
(10) Waterways of inland streams and oceans are effective through fare.

Question 32. What is the over-utilization of water?
Answer: We often misuse water sources in many ways. All citizens are made aware of the proper use of water and avoid misuse of this natural resource.

During personal use, we often discard some amount of drinking water, during bathing and washing we misuse water. In some areas, tap water on streets is always open. In many areas, agricultural fields are irrigated with underground water. Wastage of water occurs in many industries.

Question 33. Define water scarcity and mention its causes.
Answer: When the water demand is more than its occurrence, it causes scarcity.

The factors that cause scarcity of water are :
(1)due to drought – it is due to lack of rainfall for sufficient duration, severe drought, resulting in a reduction in groundwater level, and destruction of grassland and crops.
(2)due to misuse of water – improper utilization and distribution of water.
(3)Global warming – Excessive heat dries out surface water.
(4)Pollution – Disposal of sewage water in streams and lakes is a wasteful technique. So sources of fresh water are polluted and wasted.
(5)Increased human demand for water and overuse of water.
(6)Increase in human population.
(7)Lack of access to safe drinking water.

Question 34. What are the consequences of overuse of water?
Answer:
(1) Reduction in agricultural productivity
(2)Extreme dryness of soil
(3)Desertification and loss of forest cover
(4)Groundwater pollution with arsenic or fluoride
(5)Gradual depletion of groundwater for drinking purposes.
(6)Affecting industrial products.

Question 35. Define water conservation. Name the various methods of water conservation.
Answer: The conservation of water by proper use and save it for future use is called conservation.

To meet the water scarcity problem, water has to be conserved by the following methods:
(1)proper distribution and utilization of water
(2)proper drainage method to be implemented
(3)increase in recharging of soil with water
(4)rainwater harvesting
(5)proper maintenance of ponds and lakes
(6)avoid misuse or overuse of water in houses and industries.

Question 36. Write the steps of Rainwater Harvesting.
Answer: It is a simple and effective method of water management by which rainwater is collected, stored, and used to meet the demand for fresh water.

This form of harvesting rainfall benefits all, particularly in areas where rainfall is less.
Rooftop rainwater harvesting forms one of the best methods, a simple and low-cost technique, requiring minimum knowledge.

It consists of 3 main steps-
(1)roof surface for collection of rainwater,
(2)gutters and drain pipes are required for the transport of water from the roof to the storage reservoir,
(3)storage tanks are used to store water.

Water from the storage tank, passed through the filter, may be used as drinking water.

Question 37. What are the advantages and disadvantages of rainwater harvesting?
Answer:
Advantages:
(1) Rainwater is generally free from germs and contaminations.
(2)It is soft water with neutral PH and does not contain any salt.
(3)Rainwater does not harm water pipes and reservoirs by corrosion.

Disadvantages :
The supply of water depends on the amount of rainfall. In rooftop farms, rainwater may be contaminated with air pollutants, animal or bird droppings, insects, etc. so it needs regular cleaning and repairing.

Question 38. What are the different sources of food?
Answer:
(1) Agriculture:
The maximum quantity of food we consume is agricultural products. These include cereals, pulses, and oil seeds. Disease-resistant grains are raised and seeds are vernalised by special treatment.

(2)Horticulture :
The practice of growing flowers, fruits, and vegetables is called horticulture. Hybridization techniques and modern methods of cultivation are being used for the production of new varieties.

(3)Animal husbandry:
The breeding, feeding, and caring of domestic animals is called animal husbandry. It provides us with meat and dairy products.

(4)Fishery:
Scientific breeding and rearing of fishes. There are freshwater fishes and marine water fishes. They are rich in protein, vitamins, minerals and fats.

Question 39. What are alternative food sources?
Answer: To meet the additional demand for food, scientists and nutrition experts have found dietary potential in some plant products, other than the common food materials.

Bacteria and fungi are used for preparing bread, alcoholic drinks, cheese, pickles, and yogurt.

Blue-green alga spirulina is used as food. Plant seeds form a good source of food for animals and humans. Animal sources of food are meat, milk, and dairy products. Honey is produced by bees and eggs by birds are used as food. Fungus used as food are mushrooms.

Yeast is used to produce yeast cake.

Some edible forms of algae are laminaria, Sargassum, and Porphyra. Chlorella is used as food. Bryophytes like mosses provided food for birds and mammals. The seeds of pinus giardiana (chilgoza) can be taken as food. Sago (sabudana) is a carbohydrate-rich matter extracted from the stem of palm trees.

Question 40. Write a note on “world food problem and its effect.”
Answer: The United Nations report indicated that in the years 2012-2013, more than 800 million people all over the world suffered from hunger. One of the serious earliest food scarcity in the form of famine faced by the people of Bengal caused the death of many people in 1776.

The causes of world food problems are –
(1)Slow down of production of main cereal crops
(2)Damaged caused due to natural calamity •
(3)Increase in price of food.
(4)Demand of biofuel
(5)Increased population
(6)Increasing urbanization
(7)Intensive farming and irrigation system
(8) Erosion of soil.

Question 41. What are the uses of energy?
Answer: The capacity of doing work is called energy. All forms of energy are convertible.

(1)Domestic use:
In rural areas, wood, coal, and kerosene oil are utilized as sources for cooking, lighting, and other purposes. In urban areas, it is used for lighting, heating, cooling rooms, washing machines, etc.

(2)Commercial use:
Energy is used on a large scale in hotels, malls, restaurants, and shops for lighting, cooling, and other purposes.

(3)Industrial use:
Coal, oil, and natural gas are used for heating, burning, lighting, and running machines.

(4)Transport use :
Most of the vehicles in the air, water, or on the road run with petroleum products.

Question 42. What are the reasons for growing energy needs?
Answer: The economic growth of a nation depends on energy. Just before 50 years ago, the scope of using energy was at least 10 times less than in recent days. The development of power resources in an organized manner results in the industrial development of the country.

The requirement of energy is indispensable in the fields of agriculture, transport, business, and domestic purposes. The different forms of energy in use are thermal energy, electrical energy, light energy, mechanical and chemical energy. An increase in living standards is also responsible for the increase in energy demand.

Question 43. How does the wastage of energy take place? How is energy conserved?
Answer: Wastage of energy means, losing energy without any work. More urban use with non-stop usage, unnecessary use of vehicles, and poor road conditions are some common ways to waste energy.

Energy conservation takes place through its judicious use in the following ways –
(1)Keeping the lights and fans closed when not in use in houses & offices.
(2)Switching off the ignition of the vehicles when standing a traffic signals.
(3)Regular maintenance of machines so that power consumption may be reduced.
(4)Use of solar heater.
(5)Use of better combustion technology for fuels of the vehicles.
(6)By using renewable sources of energy.

Chapter 5 Environment And Its Resources Chart Type Questions

1. Environment And Its Resources National Parks

2. Environment And Its Resources Wild Life Sanctuaries

3. Environment And Its Resources Wildlife Reserves in India

4. Environment And Its Resources Reserve Forests

5. Environment And Its Resources Biosphere Reserves

Chapter 5 Environment And Its Resources Bio Scientist

1. In 1866 Earnest Hackel coined the term Ecology.
2. In 1927 Charles Elton stated that Ecology is the scientific natural history.
3. In 1935 A. G. Tansley gave the term Ecosystem.
4. In 1966 Odum mentioned the Abiotic and Biotic components of the ecosystem. He also defined the food chain in that year.
5. In 1972 Odum defined conservation.
6. In 1927 Elton gave the concept of an ecological pyramid.
7. In 1942 R. Lindeman denoted the model of energy flow in an ecosystem.
8. In 1993 wild classified land based on land use capabilities.

Question 1. Write a note on intraspecific and interspecific competition.
Answer:
1. Intraspecific competition :
There are two basic types of such competition—
(1)Scramble competition :
In such competition, the individuals of a community get access to resources sub-divided into small parts. Each individual obtaining a scarce amount of resources may not survive in the long run.

(2)Contest competition :
In such competition, the successful individuals of a community obtain the resources whereas the unsuccessful ones do not have any access to the resources.

An example of intraspecific competition is where resources are limited. The visiting flamingoes in South American lakes and fishes residing in the lakes compete for common Zooplankton.

2. Interspecific competition :
Competition takes place between individuals of different species of the same community for food, space, and other requirements that are limiting, each is affected by the pressure of the other. At times resources may not be limited by the feeding capacity of a species but may be reduced due to interference caused by other species.

An example of interspecific competition is where resources are not limited but the inhibitory influence of one species on another takes place.

Question 2. Classify plants and animals based on temperature control.
Answer: Plants are divided into four categories based on their heat-tolerating capacity—
(1) Megatherms — plants that can tolerate high temperatures throughout the year for example; desert vegetation and tropical rain forests. Tropical plants require constant high temperatures for their maximum growth,
(2) Mesotherms — plants that can withstand high as well as low temperatures; for example, tropical deciduous forests, aquatic plants,
(3) Microtherms — plants growing in regions of low temperature, for example mixed coniferous forests,
(4) Hekistotherms — plants growing in regions where the temperature is very low, for example alpine vegetation. Alpine plants are adapted for short summer periods for flowering and fruiting. Plants receive energy from absorbed solar radiation and convection and they lose heat by radiation, convection, and evapotranspiration.

Based on temperature control animals are divided into three groups :
(1)Poikilothermal or Ectothermic animals or Cold-blooded animals whose body temperature changes with changes in their environmental temperature, e.g. most invertebrates.
(2)Homeothermic or Endothermic animals or Warm-blooded animals whose body temperature is independent of the temperature of their environment, e.g. birds and mammals.
(3)Heterotherms — Animals with limited power of temperature regulation respond to extreme temperatures by aestivation and hibernation, e.g. some marsupials.

Question 3. Write a note on the different types of parasites.
Answer: Different types of parasites:
(1)Phytoparasite:
Plant parasites; for example, root nematodes, aphids, lac insects, stem borers, and wasps form galls on plants like oats, and willows. Mites from witches broom in Hackberry.

(2)Zooparasite :
Animal parasites; for example, Platyelminthes, nematodes, and arthropods.

(3)Hyperparasite:
Such parasites live on another parasite, example, Plasmodium vivax a protozoan is a hyperparasite of the female Anopheles mosquito which is a parasite of humans.

(4)Temporary parasite: Parasites like mosquitoes and bugs which suck blood from their hosts. For example, Leech (Hirudinaria) sucks the blood of cattle and man.

(5)Permanent parasite :
Entamoeba histolytica, certain platyhelminthes, nematodes, and arthropods are examples of permanent parasites.

(6)Ectoparasites:
live on the external surface of host organisms; for example, lice on humans, ticks on dogs, copepods on marine fishes, louse (Pediculus) sucks blood spreading diseases like typhus, Rat flea (Xenopsylla) — Spreads germs of plague from rat to man. Cuscuta is a rootless leafless parasite on hedge plants.

(1)Entamoeba histolytica — protozoan living in the human intestine causes amoeboic dysentery.
(2)Plasmodium vivax — a protozoan living in human blood that causes malaria.

Question 4. Define the different types of food chains with examples. What is a food web?
Answer:
Types of food chains:
There are three types of food chains — predator food chain, parasitic food chain, and saprophytic or detrital food chain.

1. Predator food chain :
A predator food chain starts from green plants and extends upto carnivores, i.e., it includes consumers only. Here the size of the living organism gradually increases, but their number gradually diminishes.

2. Parasitic food chain :
A parasitic food chain goes from larger (host) to smaller (parasite) animals.

3. A saprophytic or detrital food chain :
A saprophytic food chain goes dead organisms or organic matter into microorganisms. Such food chains are interconnected with each other to form a food web.

Examples of the food chain :
(1)Predator food chain — Grass —> Grasshopper —> Frog —> Snake —> Eagle
(2)Parasitic food chain — Plant— > Pig —> Helminth
(3)Saprophytic food chain — Dead animal —> Maggot —> Frog — Snake —> Peacock.

Food Web :
(1) Definition :
When different food chains of the same habitat are interconnected with each other to form a complicated network then the feeding relationship is known as a food web.

Question 5. Write a note on the role of animal husbandry in human welfare.
Answer:
Role of animal husbandry in human welfare :
Animal husbandry can be used to obtain a lot of benefits for mankind which are as follows —
1. Dairy products — Milk and other dairy products such as yogurt, cheese, paneer, butter, ice cream, etc. could be obtained.
2. Meat — The demand for protein is mainly covered by cattle and other animals.
3. Land management — Grazing by live stocks can be used to control the growth of weeds In the agricultural field.
4. Labour — Horses, donkeys, yaks, etc. can be used for mechanical carriers.
5. Fibre — Sheep provides fur or wool for the textile industry.
6. Fertilizer— Cow dung can be used as manure for the crop field. The blood and bones of animals are also used as fertilizer.

Question 6. Discuss the impact of light on organisms at the individual level.
Answer:
Effect of light:
(1) In green plants, chloroplasts tend to concentrate on the surface of a leaf, which gets more light,
(2) Productivity is higher in those plants that receive more and brighter light. That is why trees are more productive than submerged aquatic plants,
(3) In some plants, a span of daylight affects their growth and flowering. This phenomenon is known as Photoperiodism. Plants, such as dahlia, sugarcane, strawberry, etc. bloom in shorter daylight periods and are called Short Day Plants (SDP). The plants, such as peas, radishes, spinach, etc. bloom in longer daylight periods and are called Long Day Plants (LDP). In some plants, such as tomatoes, cucumbers, cotton, etc. daylight does not have any significant impact. These are known as Day Neutral Plants (DNP).
(4) Light enhances the pigmentation of skin,
(5) Birds and bats show circadian rhythm (daily rhythm of activities), which is controlled by light.

Question 7. Discuss the effect of temperature on organisms at the individual level.
Answer:
Effect of temperature:
(1) Plants grown in desert regions have light-colored
body hairs, acting as heat reflectors. They have fewer stomata to reduce transpiration,
(2) Plants growing in hot but humid climates of tropical regions have thick leaves to increase the rate of transpiration,
(3) In amphibians, reptiles, and fishes, body temperature varies with environmental temperature. These animals are, therefore, known as poikilothermic animals. On the other hand, birds and mammals have constant body temperature in any environment. These are known as homeothermic animals,
(4)Some animals, such as toads, house lizards, ants, etc. can withstand a wide range of temperature variations in the environment. These are called eurythermal animals. Some animals, such as fishes and other cnidarians cannot tolerate wide temperature fluctuation. These are called stenothermal animals.

Question 8. What is parasitism? Classify parasites based on their position in the host body and the duration of parasitism.
Answer:
Parasitism :
Parasitism is the most advanced type of interspecific interaction in which one species depends upon other species for food or shelter or both. Here, the dependent member (parasite) is benefited, but the helping member (host) is deprived.

Based on their position in the host body, parasites may be of two types —
(1) Ectoparasites :
These parasites draw nutrients from outside the body of the host.
Example: Louse, ticks, bedbugs.

(2) Endoparasites :
These parasites live inside the body of the host and collect nutrients from them.
Examples: Tapeworms, roundworms, Plasmodium (malarial parasite), etc.

Based on the duration of parasitism, they may be of two types —
(1) Obligatory parasites :
These species lead parasitic life throughout their life cycle.
Examples: Tapeworm, roundworm, Plasmodium, etc.

(2) Facultative parasites:
These species show parasitic behavior in certain periods of their life cycle. Example: Female mosquitoes suck blood only during egg maturation and before laying eggs.

Question 9. Write a note on the carbon cycle.
Answer:
Carbon cycle: The carbon cycle refers to the cyclic exchange of carbons in the physical and biological systems,
(1) Reservoir pool:
The carbon bed of the lithosphere acts as a reservoir pool for carbon,

(2) Cyclical pool :
Cyclical pool involves the atmosphere and the seawater

(3) Utilization of carbon from nature:
Utilization of carbon from nature involves two pathways —
(1) Biological path:
The biological path of carbon utilization involves the activities of green plants and shelled mollusks. Green plants trap carbon within cellular compounds by photosynthesis. Shelled mollusks utilize carbon of CO₂ to prepare their shell,

(2) Physicochemical path:
The physicochemical path or carbon utilization involves certain marine deposits, such as limestone, dolomite, feldspar, etc. Limestone, feldspar, etc. absorb carbon (CO₂) to prepare calcium carbonate (CaCO3).

(4) Return of carbon to nature :
Carbon is returned to the environment by two paths —
(1) Biological path :
All living forms (except a few anaerobes) release CO₂ by respiration. CO₂ is released into the nature by decomposition of organic matter. After the death of mollusks, their carbon-rich shells are decomposed to produce CO₂.

(2) Physicochemical path:
Combustion of fossil fuel, wood, etc. forest fires, and volcanic eruptions produce huge quantities of CO₂. This cyclic process of utilization and return of carbon to nature occurs at the same rate. This helps to maintain constant carbon content in the environment. Ecosystem, similar cyclic exchange also occurs in the case of other elements.

Question 10. How can energy be conserved in daily life?
Answer:
Energy conservation in daily life:
To meet our-future requirements, we need to conserve energy. By following the measures mentioned below, energy can be conserved to a large extent.

(1)Lighting :
Utilize maximum daylight by painting walls in a lighter shade. Keep lamps dust-free. Replace bulbs with CFL or LED lamps. Use electronic chokes instead of copper chokes.

(2)Fans :
Switch off the fan when you leave the room. Fit electronic regulators for ceiling as well as table fans.

(3)Electric iron :
Set the regulator at the appropriate position for ironing at medium heat. Use a sprayer to moisten clothes.

(4)Kitchen appliances :
Use mixers preferably for wet grinding. Do not the run machine in over or under-load conditions. Do not open the microwave oven’s door frequently to check food. Use flat bottom pans to get full contact with the heating plate of the induction oven.

(5)Gas oven:
Cook in regulated flame. Off it or simmer the flame during the preparation of food to save LPG. Use pressure cookers as much as possible. Cover the pans while cooking. Let items reach room temperature after taking them out of the refrigerator, before cooking.

(6)Water heater:
Install solar water heater replacing the electric water heater. Do not use the water heater for too long time.

(7)Electronic devices :
Switch off TV and audio systems when you leave the room for even short intervals.

(8) Computers:
Turn off the computer when not in use. Turn off the monitor during long downloading.

(9)Refrigerator:
Use star-rated energy-saver models. Keep it in moderate cooling mode. Do not keep the door open for a long time. Make sure that the door sealing pads are airtight. Set the refrigerator in such a position so that air can easily circulate the refrigerator.

(10)Washing machines :
Run in full load condition at optimum water level. Set a timer as recommended. Apply detergent in the right quantity. Avoid washing with hot water as much as possible. Prefer drying under the sun.

(9)Air conditioners:
Install energy saving star—rated sets. Select the set, with cooling capacity, as per the room size. Operate in moderate cooling mode. Fit the outdoor unit in a shady place. Clean filters regularly. Seal the doors and windows.

(10)Home:
Select heat-reflecting and light-shaded paints for the outside wall. Use film-coated reflecting glass in windows. Position the windows in the right place to maintain cross ventilation.

Question 11. Write a note on the abiotic components of an ecosystem.
Answer:
Abiotic Components:
Abiotic components of an ecosystem consist of nonliving factors.

These factors are of two types —
(a) Climatic and
(b) Edaphic.

The climatic factors contain temperature, light, wind, humidity, rainfall, and water whereas the edaphic factors include soil, topography, etc.

1. Temperature :
Temperature is such an important abiotic factor that it has a great influence on the distribution of organisms and their metabolism. Most organisms can survive in a temperature range of 10°—50°C.

2. Light:
It is another important abiotic factor. The intensity, quality, and duration of light have a great impact on the living world. Light provides energy to the producers for photosynthesis. The energy stored in the synthesized food by green plants is the source of energy for all types of consumers directly or indirectly.

3. Water:
Water, the most important abiotic factor, is very much essential! for life. Earth’s surface consists of 71% water. Water is one of the main raw materials of photosynthesis, which is the source of food for the living world.

4. Air:
The gases present in the atmosphere, mainly oxygen, carbon dioxide, and nitrogen have a great impact on living organisms. Oxygen is too much necessary for respiration. Carbon dioxide is used as a raw material for photosynthesis. Nitrogen is needed for synthesizing protein.

5. Soil:
It is the surface layer of land as well as it is an important edaphic factor of ecosystem. The distribution of plants like halophytes (in saline soils), lithophytes (in rocky soil), osteophytes (in acidic soils), psammophytes (in sandy soils), etc. is mainly influenced by the soil. Soil is the source of all the macro and microelements essential for living organisms.

6. Topography :
The distribution of plants and animals is influenced by different types of habitats like plains, hills, slopes, etc. Temperature decreases with altitude, so topography plays a major role in the distribution of plants and animals.

7. Minerals :
The distribution of microbes, plants, and animals depends upon the availability and concentration of minerals, which have an important role in the growth and development of the organisms.

Question 12. Define and classify the ecological pyramid.
Answer: Ecological Pyramid:
1. Definition :
The graphical representation of the gradual reduction of the trophic levels of food chains, i.e., from producers to different types of consumers forms a conical shape known as an ecological pyramid. It was denoted by Elton (1927).

The first trophic level is the base and the successive trophic levels make up the upper tiers and apex.

2. Types :
Ecological pyramids are of three types —
(1) Pyramid of numbers,
(2) Pyramid of biomass and
(3) Pyramid of energy.

(1)Pyramid of numbers:
The numerical relationship among different trophic levels is represented by a pyramid of numbers. In this type of pyramid, the number of producers is highest and the number of different consumers is decreased in the successive levels of the pyramid from bases to apex.

(2)Pyramid of biomass :
The pyramid of biomass indicates the decrease or the gradual reduction in biomass at each trophic level from base to apex.

(3)Pyramid of energy :
The energy flow in an ecosystem and total energy at each trophic level of the food chain is represented by a pyramid of energy.

Question 13. Write a note on the major types of forests in the world.
Answer: Major types of forests in the world :
1. Tropical rainforests:-
Year-round high temperatures and abundant rainfall make this a dense, lush forest. Tropical rainforests are found near the equator. They are vital storehouses of biodiversity on the planet, and yet face severe threats today, with much of their original extent depleted.

2. Sub-tropical forests:-
These are found to the sound and north of the tropical forests. The trees here are adapted to resist the summer drought.

3. Mediterranean forests:-
These forests are found to the south of the temperate regions around the coasts of the Mediterranean, California, Chile, and Western Australia. The growing season is short and almost all trees are evergreen, but mixed hardwood and softwood.

4. Temperate forests:-
Found in such places as Eastern North America, Northeastern Asia, and Western and Eastern Europe, temperate forests are a mixture of deciduous and coniferous evergreen trees. Usually, the broad-leaved hardwood trees shed leaves annually. There are well-defined seasons with a distinct winter and sufficient rainfall.

5. Coniferous forests:-
Coniferous forests inhabit the cold, windy regions around the poles. There are both hardwoods and conifers found in this region. The conifers are evergreen and structurally adapted to withstand the long drought-like conditions of the long winters, whereas the hardwoods are deciduous.

6. Montane forests:-
These are also known as cloud forests because they receive most of their precipitation from the mist or fog that comes up from the lowlands. Some of these montane woodlands and grasslands are found in high-elevation tropical and temperate zones. Plants and animals in these forests are adapted to withstand the cold, wet conditions and intense sunlight. Trees are mainly conifers.

7. Plantation forests:-
There are around 140 million hectares of “plantation forests” in the world, accounting for around 7% of global forest cover. The productivity of planted forests, in terms of supplying a sustainable volume of timber and fiber, is usually greater than natural forests.

Plantations produce around 40% of industrial wood. Both the plantation area and contribution to world wood production are projected to continue to increase in the foreseeable future.

Question 14. Discuss the stages of energy flow in an ecosystem.
Answer: Stages of energy -flow:
Now energy flow in the ecosystem takes place in three successive stages :
(1) Acquisition of energy,
(2) Uses of energy and
(3) Unidirectional flow of energy.

1. Acquisition of energy :
The source of energy in the ecosystem is solar radiation. 12.3 x 1022 calories of solar energy reach the earth each year. Of which a major part is reflected in the space due to the presence of clouds, smoke, and dust particles.

According to German Scientist Rudolf Geiger, about 42% of solar energy is reflected in space due to the presence of clouds, dust particles, etc. in the atmosphere. 10% of the solar energy and ozone, oxygen, water vapor, carbonic acid, etc. are absorbed by the suspended solid particles in the air.

In the daytime 48% of the solar energy falls on the earth. Some of the light energy is also reflected from the surface of the earth. The remaining light energy is entrapped by the chlorophyll present in the palisade and spongy parenchymatous cells of the mesophyll tissue of the leaf where photosynthesis takes place. As a result, light energy is transformed into kinetic energy which is stored as potential energy in the carbohydrate food matter.

The primary production in the ecosystem is the production of glucose by green plants. The energy released during this time is called gross production. After respiration and other living processes the energy left behind is termed as net production or NP.

2. Uses of energy :
In an ecosystem, the producers transform solar energy into chemical energy and later in the presence of water and carbon dioxide prepare carbohydrates. These plants are taken in by animals and thus potential energy is acquired by them. Again when the secondary consumers feed on primary consumers they also acquire potential energy.

Thus when tertiary consumers take in secondary consumers, we see a similar flow of potential energy to occur. Thus the main source of energy of all animals is food. The amount of energy acquired from food is called gross energy intake and in short, denoted by the letter I.

When energy flows through the different trophic levels of an ecosystem we can see that some energy is dissipated as heat at each step which is of no use.

In the year 1942, Raymond Lindemann formulated the law called the 10 percent law. According to this law, about 10% of total energy is transmitted during energy flow through several trophic levels. That is why we notice a diminution in the amount of energy. Energy used up by a body to function properly is called respiratory energy (R).

For example, about 100 kg of organic food present in the grass, will make 100|10 kg. or

10 kg. biomass in the case of herbivorous animals, and of about — kg. i.e. 1 kg biomass in case of carnivores. According to Lindemann’s 10% law, in a grassland ecosystem about 100 kg of grass would increase 10 kg of flesh in the body of a deer. If this deer is taken in by a tiger its flesh would help in increasing 1 kg of flesh in the body of the tiger. Thus a gradual diminution of energy is noticed.

The formed energy is spent in digestion, metabolism, and performing other physiological functions by an animal. Some energy is also liberated as heat and thus lost to the surroundings.

3. Energy flow is unidirectional:
Producers obtain their light energy from the solar energy. This light energy once entrapped by the chlorophyll cannot retrace its path but is given out to surroundingsding. Thus, along the trophic level energy gets transmitted step by step but once given out it cannot follow its way back. Thus the energy flow is unidirectional.

 

• Chapter 1 Life and Its Diversity
• Chapter 2 The Levels of Organization of Life
• Chapter 3 Physiological Processes of Life
• Chapter 4 Biology and Human Welfare

You can download the class 10 WBBSE Life Science book pdf from wbbsesolutions.guide

Chapter 4 Biology And Human Welfare Short Answer Questions

Question 1. What do you mean by biocontrol?
Answer: Using bacteria, viruses and some protozoa to control the pest naturally is called biocontrol.

Question 2. What are microphones?
Answer: Bacteria like Bacillus polymyxa, and Pseudomonas species of Aspergillus have the power to release phosphate from bound form and remain unable to be in dissolve states are called microphones.

Question 3. Name two free-living N, fixing bacteria.
Answer: Azotobactor and Bacillus polymyxa.

Read and Learn more about WBBSE Solutions for Class 10 Life Science And Environment

Question 4. Name two cyanobacteria.
Answer: Nostoc and Anabaena.

Question 5. What is mycorrhiza?
Answer: Symbiotic association of some fungi with roots of seed-bearing plants.

Question 6. Name one symbiotic bacterium.
Answer: Rhizobium leguminosarium.

Wbbse Class 10 Life Science Solutions

Question 7. Where from azotobactrine produced?
Answer: from the bacterium Azotobactor.

Question 8. What is meant by immunity?
Answer: The ability of the human body to resist almost all types of pathogenic microbes, toxins and other antigens.

Question 9. Name the parasites responsible for causing different types of human malaria.
Answer: Plasmodium vivex, Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale.

Question 10. What are AIDS-related complexes?
Answer: AIDS-related complex is the most serious form of AIDS and is characterised by swollen lymph nodes, night sweats, fever and loss of weight.

Question 11. Name the pathogen of pneumonia.
Answer: Pneumonia is mainly caused by a diplococcus bacterium.

Question 12. What is allergy?
Answer: Allergy can be defined as an appropriate and excessive immune response of a person to some harmless common environmental substances, which come in contact with or enter the body.

Wbbse Class 10 Life Science Solutions

Question 13. Expand AIDS and HIV.
Answer: Acquired Immuno Deficiency Syndrome. Caused by a virus known as Human Immuno Deficiency Virus. There are three species of HIV which infect human beings: HIV-1, HIV-2 and HIV-3.

Question 14. Who is the “Father of Immunology”?
Answer: Louis Pasteur. He coined the term vaccination.

Question 15. What is interferon?
Answer: A small protein produced by vertebrate cells either naturally or in response to viral infection, which is capable of inhibiting viral multiplication.

Question 16. Which kind of Ig is most abundant in blood?
Answer: Ig G

Question 17. What is the chemical nature of antibodies?
Answer: Glycoprotein.

Question 18. What kind of immunity is achieved by vaccination?
Answer: Artificial active immunity.

Question 19. What is a booster dose of vaccination?
Answer: It is a subsequent dose of vaccine given after the primary dose to develop the effective and high level of antibody in blood for long-lasting immunity.

Question 20. Who discovered that the female anopheles mosquito is the vector of Plasmodium?
Answer: Sir Ronald Ross.

Question 21. Why male mosquitoes can not transmit malaria?
Answer: Because their mouth parts are not adopted for piercing human skin and bloodsucking.

Question 22. Who first coined the term antibiotics?
Answer: Selman Waksman in 1942.

Question 23. Name four products produced due to the fermentation of yeast.
Answer: Ethyl alcohol, Butyl alcohol, Acetaldehyde and phenyl ethanol.

Wbbse Class 10 Life Science Solutions

Question 24. What are probiotics?
Answer: When fermented milk products, idli, and dosa are taken in our body then they produce a special kind of microbes within the digestive system of human beings called probiotics.

Question 25. What is rennet?
Answer: From the stomach of the calf rennet is extracted which contains an enzyme renin used in cheese making.

Question 26. What is BOD?
Answer: Biological Oxygen Demand. The amount of biodegradable organics present in water is not measured directly but measured in terms of the requirement of oxygen of the microbial degradation process at 20°C, which is called Biological Oxygen Demand.

Question 27. What is biological control?
Answer: A natural method of pathogen and pest control in which bacteria, viruses and other insects like agents take part is called biological control.

Question 28. What is leg haemoglobin?
Answer: Within the root nodules of leguminous plants lies a haemoglobin-like compound called leg haemoglobin. It facilitates the diffusion of oxygen to the very rapidly respiring nitrogen-fixing symbiotic bacteria within the root nodule cells.

Question 29. Which type of blue-green algae is associated symbiotically with Azolla?
Answer: Anabena azolla.

Question 30. Which disease is known as “break-bone fever”?
Answer: Dengue.

Question 31. Expand OPV, BCG, DPT, WASH, MMR AND UNICEF.
Answer:
OPV – Oral Polio Vaccnine
BCG – Bacillus Calmette Guerin
DPT – Diptheria Pertusis Tetanus
WASH- Water, Sanitation and Hygiene
MMR – Measles, Mumps, Rubella
UNICEF – United Nations International Children’s Emergency Fund.

Question 32. What is vaccination? Give one example of the vaccine.
Answer: The process by which weak or dead pathogens are injected into the body to produce immunity against infectious disease by producing antibodies is called vaccination.

The principle of immunisation or vaccination is based on the property of ‘memory, of the immune system.

Question 33. What is immunisation? What do you mean by natural immunity and artificial immunity?
Answer:
Active immunity:
When a person is exposed to an antigen, the lymphocyte of his own body produces antibodies. This is called active immunity.

Passive immunity:
When pre-formed or ready-made antibodies are directly given to a person to protect the body, it is called passive immunity.

Question 34. Briefly describe the structure of the antibody.
Answer: Chemically antibody molecules are proteins in nature like globulins of blood plasma. So these molecules are also known as immunoglobulins (Ig). An immunoglobulin molecule is a ‘Y’ – shaped structure. Each molecule has specific antigen-binding sites by which it attaches with a specific antigen to inactivate it.

Wbbse Class 10 Life Science Solutions

Question 35. State the purpose of the WASH program.
Answer:
One objective:
The overall objective of UNICEF in the area of water, sanitation and hygiene (WASH) is to contribute to the realization of children’s rights to survival and development through the promotion of the sector and support to national programmes that increase equitable and sustainable access to, and use of, safe water and basis sanitation services, and promote improved hygiene.

Question 36. State two points of importance of biofertilizers.
Answer:
(1) The yield of plants can be increased by 15% – 35% by the application of biofertilizers.
(2) The inoculum which has to be applied in the field can be prepared by the farmers themselves.

Question 37. What are microphones?
Answer: Some bacteria like Bacillus polymyxa, Pseudomonas striata, and species of Aspergillus have the power to release phosphate from bound or immobile form and remain unable to be in dissolved states. These biofertilizers are called microphos.

Chapter 4 Biology And Human Welfare Descriptive Type Questions And Answers

Question 1. Define Immunity.
Answer: Immunity means the body’s defence against disease. The body has numerous methods of preventing and curing infections. The defence system in our body works at two levels-

1. Local Defence System:
It tackles the germs in their possible points of entry. It includes a protective mechanical barrier, germ-killing secretion and germ-fighting WBC.
2. Immune System:
It deals with the germs after they have entered into the body tissue.

Immunity may be defined as the “Capacity of our body to deal with foreign substances that enter our body and to render them harmless”.

Wbbse Class 10 Life Science Solutions

Question 2. Classify immunity.
Answer:

Question 3. Differentiate between Active and Passive Immunity.
Answer:

Question 4. Difference between antigen and antibody.
Answer:

Question 5. What are antigens and antibodies?
Answer: Antigen:
These are foreign substances which, on entering into the body evoke an immune response and are responsible for specific reactions with the antibodies. Since the antigens induce immune responses, they are also called immunogens.

Antigenes are usually found on the cell surface of pathogenic microbes. They enter into the body through food, beverages and air.

Antibodies:
These are special chemicals found in the blood which act against the germs. These are proteins and are produced on exposure to antigens. These are specific, which means that one kind of antibody acts against only one particular type of antigen.

Wbbse 10th Class Life Science Question Answer

Question 6. Draw the National Immunisation Schedule.
Answer:

Question 7. How do microbes help us in our everyday life?
Answer:
Biocontrol agents:
The use of microbes to control pathogenic pests is termed as biological control.

(1) Bacteria:
(1) bacteria like Bacillus thuringiensis (Bt) can be utilised to control butterflies, caterpillar which act as microbial biocontrol agents. These Bt toxin genes when introduced into cotton plants, such plant get the power to resist the attack of insect pests.
(2) Ladybird beetles provided with red and black markings live by eating aphids.
(3) Bs toxin may be transferred to aquatic cyano-bacteria that kill the mosquito larva.

(2) Virus:
Baculovirus, a group of viruses, can destroy sawflies, mosquito larva stem borers, etc. The bacteriophage virus can destroy salmonella bacteria from water bodies.

(3) Protozoa:
Nosema sp. are protozoa microbes that directly penetrate the epithelium of insect gut and kill them. Metlasia grandis effectively control cotton ball weevil.

(4) Fungi :
The free-living fungus Trichoderma influences some plant pathogens as a biocontrol agent. Cordyceps is pathogenic to plant pathogenic nematodes. Use of microbes as biofertilizers: Microorganisms like bacteria, cyanobacteria and fungi when added to the soil, enrich the soil nutrients due to their biological activity and thereby increase the nitrogen content of the soil biofertilizer.

Free-living bacteria like Azotobactor and Clostridium and symbiotic bacteria like Rhizobium enrich the soil with nitrogen. Pseudomonas convert complex organic phosphate to simpler soluble inorganic phosphate which are easily utilized by plants. These biofertilizers are called microphos.

Rhizobium leguminosarium can fix nitrogen in peaplant. Rhizobium phaseoli can fix nitrogen in beans. Rhizonbium Japanicum can fix nitrogen in soybean.

Nostoc and Anabena are free-living cyanobacteria that act as biofertilizers in paddy fields.

Mycorrhiza :
The symbiotic association of some fungi with the roots of seed-bearing plants is called mycorrhiza. In this association, the fungi develop hyphae around the rood tip. They increase the life span of the roots of plants by providing food to them. They play an important role by absorbing selective elements.

Wbbse 10th Class Life Science Question Answer

Question 8. What are the concepts and components of WASH? Write its significance in eliminating disease burden.
Answer: WASH stands for water, sanitation and hygiene. Programm UNICEF (United Nations International Children Emergency Fund) has developed a global strategy to lift the standard of health of school children by providing them with adequate safe drinking water, proper sanitation and a sense of hygiene. This programme is popularly known as WASH. Besides providing water and sanitation facilities in school, children are made aware of the importance of washing hands before taking food. This can reduce waterborne disease.

According to UNICEF, there are three main components-
(1) To enable a child-friendly environment in the school.
(2) To improve hygiene behaviour among the students
(3) To build infrastructure for water supply and sanitation services.

Question 9. Define antigens. Write the chemical nature of antigens.
Answer: Antigens are foreign proteins which initiate immune response after entering the body and are capable of the production of specific antibodies from B-lymphocytes and interaction with the antibodies.

Chemical nature:
Antigens are large and complex molecules. Most often they are proteins. Nucleic acid, lipoprotein, glycoprotein and certain large polysaccharides may also act as antigens.

Question 10. What are epitopes? What are antibodies? Write the chemical nature of antibodies.
Answer:
Epitopes:
The specific portion of an antigen which is recognised by B and T- Lymphocytes of the immune system and to which an antibody binds is called epitopes. The epitopes are variously shaped, structurally distinct regions located on the surface of an antigen molecule. The sequence of amino acids in an epitope determines its shape.

Antibodies:
An antibody is a protein produced in the body in response to the entry of an antigen and is capable of reacting specifically with the same antigen to inactivate it. Thus antigens are antibody generators and antibodies are antigen destroyers.

Antibodies are also called immunoglobulins (Igs). The basic structure of the antibody molecule consists of four polypeptide chains. There are two long chains called heavy chains and two short chains called light chains. The four chains are held together by a disulphide bond forming a ‘Y’ shaped molecule. The Ig molecule has a constant part and a variable part. The variable part is located at the top of two arms of the Y and it contains the antigen binding site and forms an antigen-antibody complex. As a result of this antigen-containing micro-organisms are destroyed.

Question 11. Name some common diseases in humans. Mention their causative organism and symptoms.
Answer:

Question 12. What is vaccination? Name the different types of vaccines.
Answer:
Vaccination:
Vaccination is the introduction of any kind of dead or weakened germs into the body of a living being to develop immunity against the respective diseases.

Different types of vaccine:
A vaccine may be the preparation of any one of the following four categories:
(1) Killed germs:
As the TAB vaccine for typhoid

Salk’s vaccine for poliomyelitis
Rabies vaccine for dog bite

(2) Living weakened germs:
As the vaccine for measles BCG vaccine for tuberculosis.

(3) Living fully virulent germs:
As for smallpox. In this vaccination, a person is inoculated with cowpox virus which is very similar to smallpox virus.

(4) Toxoids:
As for diphtheria and tetanus. The toxoids are extracts of toxin secreted by bacteria and these poison are made harmless by the addition of formalin. Such extracts are called toxoids.

Question 13. Name the different types of antibodies with their location and functions.
Answer: Based on their physical, chemical and physiological nature, antibodies are grouped into five categories –

IgA: Found in body secretion like saliva, tears, milk etc. It provides a primary defence mechanism against local inflexion.

IgD: Found mainly on the plasma membrane of lymphocytes. It acts as an antigen receptor. It is effective against toxins and allergens.

IgE: It is located on mast cells and basophils. It protects against parasitic worms.

IgM: It is found in blood and lymph. It is the largest immunoglobulin. It helps to body defence.

IgG: It is found in blood, lymph and intestine. It protects the body against bacteria and viruses by phagocytosis.

Question 14. Define Vaccine and Vaccination.
Answer: A vaccine is a suspension of antigenic material used for the prevention of an infectious disease. It contains live but weakened micro-organisms or killed micro-organisms. Vaccination is the introduction of any kind of dead or weakened germs into the body of a living being to develop immunity against the disease.

Wbbse 10th Class Life Science Question Answer

Question 15. How microbes are related to human welfare?
Answer: Microbes like bacteria and fungi grow in the media rich with nutrients forming calories.

They help in human welfare in the following ways
(1) In industrial food processing like preparation of dairy products, dough, single cell protein which serve as a source of modern food etc.
(2) Beverages obtained due to fermentation by yeast.
(3) Bacteria and fungi are used in the preparation of antibiotics. Antibiotics are chemical substances liberated from some microorganisms which inhibit the perfect growth and proper development of other microorganisms.
(4) Several organic acids are produced by the microbes as industrial products.
eg. acetic acid and lactic acid.
(5) Certain microbes are used in Sewage treatment. Wastewater and excrement are carried away in sewers.
Eg. Methanogen bacteria
(6) Microbes help in energy generation. Biogas is used as an excellent fuel produced due to the anaerobic breakdown of biomass by the use of methanobacterium.

Question 16. Write about the importance of microbes in agriculture.
Answer:
(1) Microbes as fertilizers:
Micro-organisms like bacteria, cyanobacteria and fungi when added to the soil, enrich the soil nutrients due to their biological activity and thereby increase the nitrogen content of the soil called biofertilizers.

(2) Microbes as biocontrol agents:
The use of bacteria, viruses and other insect-like agents to control pests and pathogens in the natural method is called biocontrol Bacillus thuringiensis (Bt), is a bacterial species that has the power to kill different insect pests.

Question 17. State the importance of lymphocytes.
Answer:
Role of Lymphocyte:
(1) Large lymphocytes are immature. During maturation large lymphocyte gradually loses cytoplasm and becomes a small lymphocyte which is matured.
(2) Small lymphocytes can be of two types – B-lymphocyte and T-lymphocyte. B- B-lymphocyte is produced and matured in bone marrow, whereas T-lymphocyte is produced in bone marrow but matured in the Thymus gland.
(3) When the B-lymphocyte is stimulated by an antigen, it produces a specific antibody. This is called humoral immunity.
(4) T-lymphocyte recognises the antigen or part of antigen. This is known as cellular immunity.
(5) T-lymphocyte stimulates B-lymphocyte to form antibodies.

question 18. Define the different types of immunity with examples.
Answer:
1. Inherited Immunity (Innate Immunity):
This immunity is present at the time of birth, e.g. Different types of WBC are present in the blood of a newborn body. These WBCs will protect the body against antigens as soon as it is exposed to air outside the mother’s body immediately after birth.

2. Acquired Immunity:
The type of immunity which is acquired by a person during his lifetime is called acquired immunity.

3. Active immunity:
When a person is exposed to an antigen, the lymphocyte of his own body produces antibodies. This is called active immunity.

4. Passive immunity:
When performed or readymade antibodies are directly given to a person to protect the body, it is called passive immunity.

Wbbse 10th Class Life Science Question Answer

Examples:
(1) Acquired active natural immunity- Once someone suffers from pox, generally pox virus cannot attack him any more.
(2) Acquired active artificial – Vaccination and stimulation of lymphocytes to produce antibodies, e.g. Injection of cholera vaccine.
(3) Acquired passive natural – Mother’s IgA enters the body of the baby along with milk; the mother’s IgG enters the foetus through the placenta.
(4) Acquired passive artificial-performed antibody (antivenom) from a rabbit or horse may be injected into a snake bite patient.

Question 19. How do vaccines work in our body? State the use of vaccine.
Answer: Vaccines “teach” our body how to defend itself when germs, such as viruses or bacteria, etc. invade the body. The steps are –
(1) The body is exposed to a very small, very safe amount of virus or bacteria that have been weakened or killed.
(2) Our immune system then learns to recognize and attack the infection, if our body is exposed to that infection later in life.
(3) As a result, our body will not become ill or we may have a milder infection. This is a natural way to deal with infectious diseases.

Uses of vaccination:
A vaccinated person develops immunity against diseases like Mumps, Tuberculosis (TB), abies (causing hydrophobia), Polio, Cholera, Measles, Tetanus, Typhoid, Smallpox, and so on when vaccines for those diseases are injected into their body.

Question 20. State the historical development of vaccines.
Answer:
Historical perspective:
Edward Jenner and Vaccination :
For many centuries, smallpox devastated mankind. In modern times, we don’t have to worry about smallpox. We are grateful for the remarkable work of Edward Jenner. With the rapid advancement of vaccination, the historic origin of immunisation is often forgotten.

Edward Jenner (17 May 1749-26 January 1823) was a British physician and scientist who was a pioneer of smallpox vaccine, the world’s first vaccine. He is often called as “the father of Immunology”. It is said that “Jenner’s work saved more lives than the work of any other human.”

Jenner observed that milkmaids were generally immune to smallpox. Cowpox is a disease in cows, similar to smallpox, but much less virulent. Jenner noticed that cows suffering from cowpox form blisters from where pus comes out. While handling the cow, milkmaids received this pus from a cow. This cowpus protected the milkmaids from smallpox. Jenner collected this pus from cows and also from cowpox blisters on the hands of milkmaids. He then inoculated the material to different persons who developed immunity against smallpox and did not suffer from smallpox any more.

Jenner’s discovery was accepted and vaccination was recognised in 1840 by the British Government.

Question 21. Write a short note on nitrogen-fixing bacteria.
Answer: Symbiotic nitrogen-fixing bacteria: Hellriegel and Wilfarth (1888) showed that the leguminous plants with root nodules were able to increase the percentage of nitrogen in the soil. Within the root nodules reside a type of bacterium. He suggested that there lies a symbiotic relationship between the nodule bacteria and the host plant. That symbiotic bacterium was named Bacillus radicicola by Beijerinck (1888). Later on, it was renamed Rhizobium leguminosarium by Frank (1890).

The gram-negative, rod-shaped bacterium Rhizobium enters from the soil as infection threads into the roots of Leguminous plants, where due to the influence of certain substances like biotin or amino acid, enzymes, sugars and vitamins, may cause the root cells to divide forming root nodules. Certain growth substances like Indole Acetic Acid (IAA) secreted by the bacteria cause root hairs to curl.

Symbiotic nitrogen-fixing bacteria Rhizobium leguminosarium is residing in the root nodules of leguminous plants and converts nitrogen of air to soluble nitrates. Nitrates are used by host plants which results in increased growth and yield. With the death of host plants, root nodules release bacteria as well as nitrates into the soil whereby increases the fertility of the soil. Symbiotic bacteria Rhizobium fixes atmospheric nitrogen in the presence of a pigment called leghaemoglobin.

Within the root nodules of leguminous plants lies a haemoglobin-like compound called leghaemoglobin (LHb)- the only haemoglobin-like protein found to be present in higher plants. It facilitates the diffusion of oxygen (O2) to the very rapidly respiring nitrogen-fixing symbiotic bacteroids within the root nodule cells, thereby stimulating ATP production. The addition of phosphate fertiliser increases the efficiency of nitrogen fixation and in turn, increases crop yield.

Frankia, a nitrogen-fixing mycelial bacterium under Actinomycetes, is associated symbiotically with the root nodules of several non-leguminous plants Casuarina, Myrica, Rubus, Alnus, etc.

Question 22. State the importance of biofertilizers.
Answer: Some points of importance of biofertilizers are stated as follows:
(1) The yield of plants can be increased by 15% – 35% by the application of biofertilizers.
(2) The inoculum which has to be applied in the field can be prepared by the farmers themselves.
(3) The soil texture was improved by the biofertilizers.
(4) In semi-arid conditions biofertilizers are also effective, giving a good result.
(5) They disallow pathogens to grow vigorously.
(6) Some vitamins and growth-promoting biochemicals can also be produced by
them.

Question 23. What is mycorrhiza? Explain the two types of mycorrhiza.
Answer:
(1) Mycorrhiza :
The symbiotic association of some fungi with the roots of seed-bearing plants is called mycorrhiza.

(2) Types of Mycorrhiza: Two types –
1. Ectotrophic mycorrhiza or Ectomycorrhiza :
In this case, the fungus lives outside the tissues of the root of Pine, Oak, Eucalyptus, Alunus, Betula, etc. The fungus replacing the normal root hairs of the plants forms a covering or mantle outside the roots of trees. This mantle increases the surface area of absorption, thereby increasing the uptake of water and mineral nutrients and in turn, increases plant vigour, growth and yield.

This mycorrhiza absorbs and stores nitrogen, phosphorus, potassium, and calcium in its fungal mantle. Simpler organic molecules are formed from complex organic molecules by them. They also convert insoluble organic compounds into soluble and easily absorbable forms. A network is formed when the fungal hyphae penetrate the intercellular spaces of the cortex of the root to form finally a net-like structure. This is called Hartig net.

2. Endotrophic mycorrhiza or Endomycorrhiza :
When a fungus lives inside the root cortex and does not form a mantle on the surface of the root, this mycorrhizal association is called endotrophic mycorrhiza. These associations are found in herbaceous species like orchids and some woody plants. Here fungus produces loosely interwoven hyphae, some of which penetrate the soil while others grow on the root cortex.

In the cortex, some hyphae grow in between the cortical cells, while some penetrate the cortical cells forming swollen vesicles or finely branched hyphal masses called arbuscles. This fungal association is called vesicular-arbuscular mycorrhiza (VAM). Mycorrhizal association is noted in the root of legumes, cereals, tobacco, soybean and many orchids like Vanilla, Neottia, etc.

Question 24. State the importance of mycorrhizas in plants.
Answer:
Importance of Mycorrhizas about plants:
(1) They increase the life span of the roots of plants by providing food to them.
(2) They increase the surface area of roots of host plants by mantle formation.
(3) Fungus spread their mycelia into the soil from where they absorb different kinds of nutrients causing increased growth of the plant.
(4) Mycorrhizas play an important role by absorbing selective elements like Ca, K, Fe, Br, Cl, S and N which move easily and also elements which do not move like Zn, Cl, P.
(5) Some of the mycorrhizas produce metabolites which can change the power of plants to develop roots from wood plant cuttings. They enhance better development of roots during vegetative propagation.
(6) The resistance power of plants also increases. They make less effect of pathogens and pests on host plant health so that they become free from illness.

Question 25. Define antigens and antibodies with examples.
Answer: Antigen and Antibody:
The natural defence system of our body involves two substances
(1) antigen and
(2) antibody.

Antigen:
The foreign substances (pathogens & toxins), which on entering our body activate the body’s immune system to produce specific antibodies are called antigens. Antigens are also called attackers.
Examples of antigens:
(1) Antigens mainly include simple or conjugated proteins (glycoproteins, lipoproteins, nucleoproteins, etc.), present on the surfaces of viruses, bacteria, fungal spores, etc.
(2) Chemicals synthesized in the cells of pathogens may act as antigens.
(3) New proteins produced by cancer cells or virus-infected cells are antigenic.
(4) Toxic chemicals like snake venom and insect venom are also antigens.

Antibody:
The defensive protein molecule which is produced in the body in response to a specific antigen to inactivate it, is called an antibody.

Question 26. What is an immune response? Classify it.
Answer:
Immune response:
The formation of antibodies in response to a specific antigen in the body is known as the immune response. It is a complex process, which is discussed below.

Types of immune response:
Immune response is a combination of two types of responses-
(1) cell-mediated response and
(2) humoral response.

Cell-mediated response :
As soon as the antigen enters into the body, T- T-lymphocytes or T-cells quickly proliferate in the thymus (‘T’ here indicates thymus). T- cells are of different types, and perform different functions.

Question 27. State the different types of T-cells with their functions. State the different types of B-cells with their functions.
Answer:

Question 28. How do microbes act as bio-control agents?
Answer: Bio-control agents:
Several harmful organisms are spread in the environment from crop fields to water reservoirs. Scientists have found certain microbes which can act as natural enemies of those undesired organisms and reduce their population to a manageable level. These microbes are known as bio-control agents. There are some bacteria, viruses, fungi and protozoa that can be used as bio-control agents.

Bacteria as a bio-control agent:
Bacillus thuringiensis produces a poison, called BT toxin, which is used to control the larvae of moths, beetles and flies. Scientists have introduced some genetic materials of these bacteria in corn and cotton plants. As a result, BT toxin is synthesized in it, so that insect parasites cannot attack these plants.

Virus as a bio-control agent:
(1) Caudovirales is a group of phage viruses, which kill Salmonella (bacteria) from water bodies. This phage virus can be used to eliminate Salmonella from drinking water to protect us from severe diarrhoea.
(2) Nuclear Polyhedrosis Virus (NPV) or Cytoplasmic Polyhedrosis Virus (CPV) can kill larvae of moths and butterflies. These viruses are used to destroy some harmful insects like pine sawflies, gipsy moths, tussock moths, etc.

Protozoa as a bio-control agent:
(1) Nosema locusta is a protozoan microbe, which is used to control harmful grasshoppers.
(2) Mettasia grandis, another protozoa, effectively controls cotton ball weevils.

Fungus as a bio-control agent:
Beauveria bassiana is a fungus which can control mosquito populations effectively. It can be used in those areas where mosquitoes have developed resistance against chemical insecticides. It can also control termites, whiteflies and many other insects.

Question 29. How do microbes act as bio-fertilizers?
Answer: Bio-fertilizers :
Certain microbes have a special ability to absorb atmospheric nitrogen and transform it into nitrates. After the death of these microorganisms, the trapped nitrogen gets mixed in the soil to increase its fertility. These microbes are now cultured and applied scientifically in crop fields to increase crop production. Therefore, these microbes are popularly known as bio-fertilizers.

Some of the bio-fertilizers are mentioned below.
Bacteria as bio-fertilizers:
(1) Rhizobium leguminosarum is.a symbiotic bacteria present in the root nodules of leguminous plants. These bacteria trap atmospheric nitrogen and convert it into nitrates. Ultimately this nitrate is transferred to the plant body as an essential nutrient.
(2) Some soil-living aerobic bacteria can absorb atmospheric nitrogen into the cells. After death, this nitrogen is released into the soil as nitrates and increases its fertility. Azotobacter sp., Azomonas sp., Derxia sp., Azospirillum sp., etc. are some examples.
(3) Among the anaerobic nitrogen-fixing bacteria, Clostridium, Chromatium, and Chlorobium are mentionable.

Cyanobacteria as bio-fertilizers:
Some cyanobacteria or blue-green algae can trap atmospheric nitrogen. These include Anabaena sp., Nostoc sp., Aulosira sp., Stigonema sp. Plectonema sp., etc. These blue-green algae are now cultured in the water of paddy fields. When these algae die and decompose, nitrates get absorbed in the soil and increase its fertility.

Mycorrhiza as bio-fertilizer:
Mycorrhiza is a symbiotic association between the roots of some plants and some fungi. In this association, the fungi develop hyphae (fine filaments of the fungal vegetative body) around the root tip or inside the cortex of roots. Mycorrhizal hyphae absorb phosphorus and nitrogenous nutrients from soil very efficiently. Besides this, it can remove harmful heavy metals like lead, mercury etc. from soil to reduce soil pollution. Mycorrhiza is formed in pines and some crop plants. The fungi involved in the formation of mycorrhiza are Boletus sp., Amanita sp., etc.

Question 30. Describe the different ways in which antibodies work.
Answer: Antibodies work in different ways:
1. Neutralizing an Antigen:
The antibody can bind to an antigen, forming an antigen-antibody complex. This forms a shield around the antigen, preventing its normal function. This is how toxins from bacteria can be neutralized or how a cell can prevent a viral antigen from binding to a body cell thereby preventing infection.

2. Activating Complement:
Complement is a group of plasma proteins made by the liver that normally are inactive in the body. An antigen-antibody complex triggers a series of reactions that activate these proteins. Some of the activated proteins can cluster together from a pore or channel that inserts into a microbe’s plasma membrane. This lyses (ruptures) the cell.

3. Precipitating Antigens :
Sometimes the antibodies can bind to the same free antigen to cross-link them. This causes the antigen to precipitate out of the solution (a process called agglutination), making it easier for phagocytic cells to ingest them by phagocytosis.

4. Facilitating Phagocytosis:
The antigen-antibody complex signals phagocytic cells to attack. The complex also binds to the surface of macrophages to further facilitate phagocytosis.

Question 31. Write a short note on the experimental vaccine.
Answer: Experimental Vaccine:
Several innovative vaccines are also in development and use:
(1) Dendrite cell vaccines combine dendritic cells with antigens to present the antigens to the body’s white blood cells, thus stimulating an immune reaction. These vaccines have shown some positive preliminary results for treating brain tumours.
(2) Recombinant vector-by combining the physiology of one microorganism and the DNA of the other, immunity can be created against diseases that have complex infection processes.
(3) DNA vaccine-in recent years a new type of vaccine called DNA vaccine, created from an infectious agent’s DNA, has been developed. It works by insertion (and expression, enhanced by the use of electroporation, triggering immune system recognition) of viral or bacterial DNA into human or animal cells.
(4) T-cell receptor peptide vaccines are under development for several diseases using models of Valley Fever, stomatitis, and atopic dermatitis. These peptides have been shown to modulate cytokine production and improve cell-mediated immunity.

Question 32. Write a short note on the comprehensive package for priority countries by UNICEF under the WASH programme.
Answer: Comprehensive package for priority countries:
1. Promoting a balanced notional WASH programming framework:
UNICEF will encourage a three-pillar approach including the provision of water supply and sanitation services that are complemented by the promotion of improved hygiene behaviour and supported by an enabling environment.

2. Supporting intersectoral approaches:
Maximum child survival and development benefits are realized when hygiene, sanitation and water programmes are coordinated or integrated with other sectoral programmes including education, health and nutrition.

3. Providing catalytic and continuous support for scaling up sustainable WASH Programmes :
Targets will be met only when national service delivery programmes are significantly scaled up, and UNICEF will prioritize support activities that contribute to this end. However, increased coverage without improved sustainability is not true scaling-up, and UNICEF will actively work to identify and promote models to improve the sustainability of WASH services.

4. Supporting community management through effective decentralisation processes:
UNICEF will support measures that help create strong institutions at the intermediate level (municipal, district, province, etc.) since they are critical to supporting community-managed service provision, which is in turn essential to the sustained scaling up of WASH coverage.

5. Promoting safe and sustainable water supplies through improved water resources management:
UNICEF and its partners in the WASH sector have a responsibility to promote and implement measures to protect the freshwater resource base.

6. Focusing on sanitation, water quality and hygiene at the household level :
There is increasing evidence that a greater focus on the household level increases the effectiveness of sectoral programmes, especially in the areas of sanitation, water quality and hygiene promotion.

UNICEF will continue to promote affordable, safe household latrines; technology development in the area of household water treatment, and programmes that seek to improve household hygiene practices.

7. Addressing a child’s right to health and education through the provision of WASH in schools:
UNICEF is committed to ensuring that all children have access to high-quality water and sanitation services at school and the benefit of hygiene education. School-based WASH activities represent an opportunity to directly address a child’s right to both education and health.

Question 33. Write a short note on the package for all countries by UNICEF under the WASH programme.
Answer: In all countries:
Strategies for all other countries where UNICEF works:
1. Advocacy and technical support for improving hygiene awareness and promoting behaviour change:
Including education, health, nutrition and young child survival and development programmes.

2. Technical support for water quality:
In the areas of water safety planning, water quality monitoring and quality mitigation programming.

3. Development of emergency preparedness plans for WASH:
Drawing on its competencies in emergency WASH programmes, UNICEF provides appropriate assistance to governments and other stakeholders in the development of national plans for WASH emergency preparedness.

4. Support to national monitoring for the achievement of MDG target 10:
UNICEF, with WHO, is the focal agency for global sector monitoring, and UNICEF also provides technical support for monitoring at the national level.

• Chapter 1 Life and Its Diversity
• Chapter 2 The Levels of Organization of Life
• Chapter 3 Physiological Processes of Life
• Chapter 5 Environment and its Resources

Chapter 3 Heredity And Common Genetic Diseases Short Answer Questions

Question 1. What is Photosynthesis?
Answer: The anabolic reaction that occurs between carbon dioxide gas and water in the presence of sunlight and chlorophyll to produce glucose is known as photosynthesis.
Equation :- 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H_{2 mkn}O + 6O₂

Question 2. What are the raw materials necessary for the process of photosynthesis?
Answer:
(1) Carbon dioxide gas (CO₂) and
(2) Water (H₂O) is the raw material necessary for the process of photosynthesis.

Question 3. Where is mesophyll tissue located? What is its function?
Answer:
(1) Between the upper and lower epidermis of the leaf.
(2) It helps in photosynthesis.

Question 4. What do you understand by carbon assimilation?
Answer: The reduction of carbon dioxide gas to produce glucose during the dark reaction of photosynthesis is called carbon assimilation.

Question 5. What are the components of the environment necessary for photosynthesis? Where do the plants collect all these components?
Answer:
(1) CO₂ – Air, Water
(2) H₂O -Soil
(3) Light – Sun
(4) Chlorophyll – grana of Chloroplast.

Question 6. What is meant by “entrapping of solar energy” in the case of green plants?
Answer: The process by which chlorophyll molecules absorb solar energy and help to convert this energy into chemical energy is called “entrapping of solar energy”.

Question 7. Write the names of two animals that can carry out photosynthesis and the names of two plants unable to do photosynthesis.
Answer:
Name of animals —
(1) Euglena ;
(2) Chrysamoeba.

Name of plants —
(1) Agaricus;
(2) Mucor.

Question 8. In green plants which one process between photosynthesis and respiration does not occur during night and why?
Answer:
(1) Photosynthesis.
(2) Because sunlight is not available during the night.

Question 9. What is photolysis?
Answer: When sunlight falls on the surface of the green leaves of plants, some part is absorbed by chlorophyll molecules, and the remaining part is reflected from the surface to the environment. The chlorophyll molecules are changed into activated chlorophyll after absorption of light.

Activated chlorophyll splits water molecules into H⁺ion and OH” ion. OH^– ion loses one electron and is converted into OH radical. This OH radical is changed into water and oxygen gas. Water again takes part in metabolic reaction and oxygen comes out to the environment through stomata.

H⁺ ion gains one lose electron of OH^– ion and changes into a neutral hydrogen atom. It combines with NADP (Nicotinamide Adenine Dinucleotide Phosphate) and reduces it into NADPH₂. At the end of this reaction, the activated chlorophyll molecule resumes its original state.

Question 10. What is the role of carbon dioxide in photosynthesis?
Answer: Role of carbon dioxide in the process of

photosynthesis:—
Carbon dioxide is a raw material for photosynthesis. In the dark phase of photosynthesis, it is reduced to glucose. Thus both elements—carbon and oxygen-are involved in the formation of glucose.

Question 11. What is photophosphorylation?
Answer: The formation of ATP molecules with the help of ADP molecules during the light phase of photosynthesis is called photophosphorylation.

Question 12. Explain the role of water in photosynthesis.
Answer:
Role of water in the process of photosynthesis:—
Water is a raw material of CO₂. Thus it takes part in glucose formation. The oxygen of water is changed into the free form of oxygen gas which comes out through stomata.

Question 13. State the role of sunlight in photosynthesis.
Answer:
Role of sunlight in photosynthesis:—
influences the rate of photosynthesisThe intensity, quality, and duration of light influence the rate of photosynthesis. Photolysis of water occurs in the presence of light. Too much high-intensity light may even stop the process of photosynthesis. The inhibition of photosynthesis due to high-intensity light which slows down its rate is called solarization. The rate of photosynthesis is directly related to the duration of light.

Question 14, How is the O₂ — CO₂ balance in the environment dependent on the green plants?
Answer:
Importance of photosynthesis in maintaining the balance of CO₂ and O₂ in the environment:—
The percentage of CO₂ and O₂ gas in (air and water) is maintained by photosynthesis. Autotrophs take in CO₂ gas from their environment for the process of photosynthesis. They liberate O₂ gas during this process. All living organisms take in O₂ gas and give out CO₂ gas during respiration. Thus photosynthesis and respiration in a combined effect maintain the balance of CO₂ andO₂ in the environment.

Question 15. Point out the relevant difference between assimilatory starch and storage starch.
Answer:

Question 16. What are the roles of chlorophyll and sunlight during photosynthesis?

Answer:
(1) Role of chlorophyll in photosynthesis:—
Chlorophyll is a magnesium-containing green pigment present in the chloroplast of green plants. The chlorophyll pigment first absorbs the incoming solar radiation. It results in the activation of the chlorophyll. Activated chlorophyll causes the dissociation of water. Hence chlorophyll helps in the photolysis of water.

(2) Role of sunlight in photosynthesis:—
The intensity, quality, and duration of light influence the rate of photosynthesis. Photolysis of water occurs in the presence of light. Too much high-intensity light may even stop the process of photosynthesis. The inhibition of photosynthesis due to high-intensity light which slows down its rate is called solarization. The rate of photosynthesis is directly related to the duration of light.

Question 17. Discuss any two significances of photosynthesis.
Answer:
(1) Solar energy is entrapped and converted into chemical energy by this process. This chemical energy is stored within food (ex. glucose). This food is the source of energy for all living Autotrophs and Heterotrophs.
(2) CO₂ and O₂ balance is maintained by this process with the association of respiration.

Question 18. Photosynthesis is a process of energy transformation.
Answer: The conversion of one form of energy to the other form of energy is called the transformation of energy. Solar energy is converted into chemical energy during the process of photosynthesis. Therefore photosynthesis is called a process of energy transformation.

Question 19. Photosynthesis is called an anabolic process.
Answer: The cellular reaction that forms complex substances from simple substances is called anabolic process. During photosynthesis complex substance glucose is formed from the simple substances carbon dioxide and water. Energy is entrapped and the dry weight of the plant is increased.

Question 20. Why is photosynthesis called carbon assimilation?
Answer: The transformation of a simple substance into a complex substance is called assimilation. The simple substance CO2 is converted into complex substance glucose during the process of photosynthesis. Hence, photosynthesis is called carbon assimilation.

Question 21. Why is photosynthesis termed an oxidation-reduction reaction?
Answer: Water and carbon dioxide are reactants. During photolysis, H₂O is oxidized by activated chlorophyll and as a result of this, free oxygen gas is evolved. In the dark phase, CO₂ gas is reduced by ATP and NADPH₂ to produce glucose molecules.

Question 22. Why is photosynthesis called an endergonic process?
Answer: The metabolic reaction in which energy is stored, is called the endergonic process. During photosynthesis, solar energy is transformed into chemical energy and this energy is stored within glucose molecules.

Question 23. Why is assimilatory starch formed?
Answer: Glucose is produced by Photosynthesis. It is soluble in water. The concentration of water becomes high. It hampers the process of photosynthesis. To continue the process of photosynthesis glucose is converted into assimilatory starch during the day.

Question 24. Why photosynthesis and respiration are called opposite processes?
Answer:
Photosynthesis and respiration are two opposite processes:
(1) Photosynthesis is an anabolic or constructive process in which carbon dioxide and water are used by the chlorophyll-containing plant to produce glucose. Whereas respiration is a catabolic or destructive process in which glucose is broken down into carbon dioxide and water.
(2) Photosynthesis occurs in the presence of the sunlight. Light is not necessary for respiration.
(3) Photosynthesis is an energy-consuming process and the energy is stored as potential energy in glucose molecules. Respiration is. an energy-releasing process in which the stored potential energy of a glucose molecule is released as kinetic energy.

Question 25. Which type of metabolic process is photosynthesis and why?
Answer:
Photosynthesis is an anabolic type of metabolic process.

Because:-
(1) Solar energy is entrapped and converted into potential chemical energy.
(2) A complex substance glucose is formed from simple substances CO₂ and H₂O.
(3) The dry weight of the plant increases during this process.

Question 26. What is the relation between photosynthesis and energy cycle?
Answer:
Photosynthesis:-
The process by which green plants manufacture their food utilizing CO₂, and H₂O as raw materials with the help of sunlight and chlorophyll, is known as photosynthesis.

Energy Cycle:-
According to the law of conservation of energy, “Energy cannot be created nor destroyed, but transformed from one form to another.” This principle says that energy is continuously cycled in nature in different forms.

Relation between photosynthesis and energy cycle:-
The plants absorb about one percent of the sunlight falling on them. The sunlight contains solar energy. The incoming solar energy is absorbed by chlorophyll molecules. Then, by the process of photosynthesis, this solar energy is converted into usable chemical energy which is stored in the food molecule. Thus photosynthesis is involved. in the conversion of solar energy into chemical energy.

Question 27. What is the relation observed between photosynthesis and respiration occurring in green plants during the daytime?
Answer: The process of photosynthesis occurs in chloroplast. It requires CO₂ and H₂O. Glucose, oxygen, and water are produced as products of this reaction.

Respiration occurs in the cytoplasm and mitochondria of the same cell. It requires glucose and oxygen. Carbon dioxide, water, and energy are produced during respiration.

Relation:-
The process of photosynthesis and respiration occur in green plants during the daytime by helping each other. Because the end products of photosynthesis are the raw materials of respiration and the end products of respiration are the raw materials for photosynthesis. Hence both processes are interrelated.

Question 28. Define respiration.
Answer: The catabolic reaction that occurs continuously within all living cells to oxidize food substances and to change the potential chemical energy of food into kinetic energy is called respiration.

Equation :- C₆H₁₂O₆ + 6O_2→ 6CO₂ + 6H₂O + 686 K. Cal Energy

Question 29. Name any two respiratory organs of animals.
Answer:
(1) Man:—Lungs
(2) Fish:— Gills.

Question 30. Where are mitochondria located? What is its function?
Answer:
(1) Mitochondria is located in the cytoplasm of a living cell.
(2) It is the site of Kreb’s cycle. ATP is also stored within it.

Question 31. Name the two major phases of aerobic respiration.
Answer:
(1) Glycolysis or E.M.P. pathway.
(2) Kreb’s Cycle.

Question 32. Mention three main types of respiratory organs in animals.
Answer:
(1) Lungs:— Man.
(2) Trachea:— Cockroach
(3) Gills:— Fish.

Question 33. Name one respiratory organ of an animal suitable for performing respiration in an aquatic environment. In which organism does it occur? 
Answer:
(1) Gills.
(2) Fish.

Question 34. What is aerobic respiration?
Answer: The process of respiration in which complete oxidation of food takes place in the presence of free oxygen is called aerobic respiration.

Equation:- C₆H₁₂O₆ + 6O₂ ——> 6CO₂ + 6H₂O  + 686 K cal Energy.

Question 35. Name the chief respiratory organs of Amoeba, Cockroaches, Tadpole, and Bird.
Answer:
(1) Amoeba :— Plasma membrane
(2) Cockroach:— Trachea
(3) Tadpole:— Gills
(4) Bird:— Lungs with air sacs.

Question 36. What is an accessory respiratory organ? Cite two examples of animals where it is found.
Answer:
(1) The organs that are attached to the main respiratory organ and help the organism to take oxygen from another environment, are called accessory respiratory organs:
(2) (a) Magur (b) Koi.

Question 37. What is fermentation?
Answer: The partial anaerobic oxidation of organic compounds (Glucose) which occurs due to enzymatic action within the cytoplasm of microorganisms to produce different types of organic substances, i.e., Alcohol, lactic acid, etc. is called fermentation.

Question 38. What is Glycolysis?
Answer: The process of conversion of glucose into pyruvic acid within the cytoplasm of the cell in the presence of glycolytic enzymes is called Glycolysis.

Question 39. What is alcoholic fermentation?
Answer: The decomposition of organic substances in the presence or absence of oxygen but in the presence of microorganisms and one product is “Alcohol” called alcoholic fermentation.

Equation :- C₆H₁₂O₆ + Zymase Yeast, 2C₂H₅OH + 2CO₂ + 50Kcal

Question 40. What is the respiratory substance of the cell?
Answer: The organic compounds that are oxidized within living cells during respiration are called respiratory substances. Ex. Glucose, Amino acid, Fatty acid.

Question 41. What is a citric acid cycle? Why is it called so?
Answer: The process of formation of a group of eight Tricarboxylic organic acids within mitochondria is called the citric acid cycle.

Reason :
Citric acid is the first organic—acid formed within mitochondria. Hence the cycle is called the citric acid cycle.

Question 42. What is meant by — ‘Release of energy takes place in respiration’?
Answer: Potential chemical energy is stored within respiratory substances like glucose, amino acids, and fatty acids. The process of respiration converts this potential chemical energy into kinetic energy. Living organisms use this form of energy to perform their various vital function. The conversion of potential chemical energy of respiratory substances into a usable form of energy is the meaning of release of energy.

Question 43. Where and when does respiration occur?
Answer:
(1) Respiration occurs in the cytoplasm and Mitochondria of a living cell.
(2) It occurs day and night continuously.

Question 44. Name the respiratory organ of spider and tadpole larva.
Answer:
Spider — Book lung
Tadpole — External gill

Question 45. Rohu and Katla fishes are dead while on sale, but Indian Koi and Magur fishes still keep alive. How?
Answer: Because in Indian Koi and Magur fishes accessory respiratory organs, labyrinthi form and arborescent respectively are attached to the main respiratory organ, gills. These accessory respiratory organs can absorb oxygen gas in the air.

Question 46. While preparing curd, a little curd mixed with the milk helps to prepare the curd quickly. How?
Answer: The bacteria present in curd increase the rate of fermentation. So, the process of curd formation takes place quickly.

Question 47. Explain in brief why pouring oil on the sewage water kills the larvae of the mosquito.
Answer: Oil acts as a disinfectant and kills the larvae of the mosquito. It also covers the water’s surface. Due to this oxygen gas does not mix with water, In the absence of oxygen larvae can not perform the process of respiration. Hence, they die.

Question 48. Why are accessory respiratory organs necessary for some fishes?
Answer: Accessory respiratory organs are present in those fishes that live in muddy water. The percentage of oxygen is less due to the presence of mud in this water. To fulfill the requirement of oxygen accessory respiratory organs are originated.

Question 49. Why is the human lung provided with alveoli?
Answer: It increases the surface area for the exchange of gases like O₂ and CO₂. Another fact is that these are covered with blood capillaries through which the exchange of gases is possible.

Question 50. Why is aerobic respiration known as oxidative phosphorylation?
Answer: The complete oxidation of food in the presence of oxygen within living cells is called aerobic respiration. The formation of ATP mainly occurs within mitochondria in the presence of oxygen. Hence aerobic respiration is known as oxidative phosphorylation.

Question 51. Why is respiration considered as catabolism?
Answer: The cellular chemical reaction in which simple substances are formed from the breaking of complex substances is called catabolism. During respiration, simple substances like H, O, and CO, are formed from the complex substance glucose. Energy is released and the dry weight of living organisms is decreased.

Question 52. Why. is breathing rate faster in aquatic animals as compared to terrestrial animals.
Answer: Aquatic animals do more work in comparison to terrestrial animals. Hence they require more energy. To obtain more energy their breathing rate is higher. They also get less amount of oxygen from water.

Question 53. How is respiration related to nutrition?
Answer: The oxidative breakdown of substances in living cells to release energy is called respiration.

The total of processes like ingestion, digestion, absorption, assimilation, and egestion is called nutrition.

Relation:-
The process of nutrition supplies the raw materials such as glucose, amino
“acids, and fatty acids for respiration, and respiration produces energy which is necessary for nutrition. Thus both processes are complementary to each other.

Question 54. “The calorific value of the protein is 4.1-kilo calorie/gm”. Explain.
Answer: When one gram protein (Amino acid) is oxidized within the cell during respiration 4.1 kilo calorie energy is released.

Question 55. What is nutrition?
Answer: Nutrition is a combination of processes (like ingestion, digestion, absorption, assimilation, and egestion) by which living organisms receive and utilize nutrients for the maintenance of their functions and growth.

Question 56. What are the different phases of animal nutrition?
Answer:
(1) Ingestion
(2) Digestion
(3) Absorption
(4) Assimilation
(5) Egestion.

Question 57. Name any two plants of which one is autophytic and the other heterophytic.
Answer:
(1) Autophytic:- Mango, Neem.
(2) Heterophytic:—Cuscuta, Yeast.

Question 58. What are the names of the first phase and the last phase of animal nutrition?
Answer:
(1) First phase:— Ingestion.
(2) Last Phase:— Egestion

Question 59. What is food?
Answer: The nutrients which supply energy and help in the formation of body substances are called food.

Example:—
(1) Carbohydrates
(2) Proteins and
(3) Fats.

Question 60. Name two food components that do not supply energy.
Answer:
(1) Vitamins.
(2) Mineral salts.

Question 61. Name two plant sources and two animal sources of a fat type of food.
Answer:
(1) Plant:— Coconut oil and Palm oil
(2) Animal:— Butter and Ghee.

Question 62. What is heterophilic nutrition? Give example.
Answer:
(1) The mode of nutrition by which non-green plants obtain their food is called heterophytic nutrition.
(2) Example:— Agaricus.

Question 64. Define the term ‘Parasite’. Give an example of a parasitic animal.
Answer:
(1 The organisms who obtain their food from other living organisms (host) are called parasites.
(2) Entamoeba histolytica.

Question 65. Define Autotrophic nutrition.
Answer: The mode of nutrition to obtain their food utilized by green plants is called Autotrophic nutrition.
Example — Green Mango tree.

Question 66. Give one plant and one animal example of a partial parasite.
Answer:
(1) Plant partial parasite — Viscum album.
(2) Animal partial parasite — Mosquito.

Question 67. Name two parasitic plants.
Answer:
(1) Cuscuta
(2) Rafflesia.

Question 68. Mention the principal types of food. Cite one example of each type.
Answer:
(1) Carbohydrate:— Wheat, Milk.
(2) Protein:— Soyabean, Fish.
(3) Fat:— Coconut oil, Butter.

Question 69. Name one parasitic plant and its host.
Answer:

Question 70. Write two differences between parasites and symbionts.
Answer:

Question 71. Mention any two importance of the process of nutrition.
Answer:
(1) For a steady supply of energy:-
Food is the source of energy for living organisms. Simple soluble foods are supplied to the cells for the conversion of chemical energy into kinetic energy. These foods are the product of the process of nutrition.

(2) For Bodybuilding and growth:-
The process of nutrition supplies the material for body building and growth.

Question 72. Write two differences between saprophytic and symbiotic plants.
Answer:

Question 73. Why does the doctor forbid spicy food for a hepatitis patient?
Answer: Hepatitis is a liver disease. A person suffering from this disease is unable to digest spicy food due to a lack of proper functioning of the liver.

Question 74. In which part of the alimentary canal, related to the digestion of food, no carbohydrate-splitting enzyme is secreted?
Answer: Stomach.

Question 75. What do you mean by the calorific value of food?
Answer: The energy obtained by the complete combustion of 1 gm of food is called its calorific value.

Question 76. What is an enzyme?
Answer: The nitrogenous organic compounds that are produced by living cells but without taking part in biochemical reactions, within or outside a cell, change the rate of chemical reaction, are called enzymes.

Question 77. Name the two substrates on which lipase and trypsin react respectively.
Answer:
(1) Lipase:- Fat.
(2) Trypsin:— Peptone.

Question 78. Name any two properties of the enzyme.
Answer:
(1) They do not take part in a biochemical reaction.
(2) They act only in a specific medium.

Question 79. Write two important characteristics of enzymes.
Answer:
(1) All enzymes are chemically protein in nature.
(2) Enzymes return to their original state after the completion of the reaction.

Question 80. From which part of the digestive system are protein-digesting enzymes
secreted?
Answer:
(1) Stomach
(2) Small intestine.

Question 81. Mention the names and functions of two enzymes.
Answer:

Question 82. Name the enzyme present in saliva. On what type of food does it act?
Answer:
(1) Ptyalin / salivary amylase
(2) Carbohydrate (Starch)

Question 83. Write the name of a proteolytic enzyme and mention its function.
Answer:
(1) Pepsin.
(2) Function:- It acts on protein and converts it into peptone.

Question 84. What is pepsin? State its source and function.
Answer:
(1) Pepsin:- It is an example of a proteolytic enzyme.
(2) Source:- Gastric Juice of the gastric gland.
(3) Function:- It acts on protein and changes it into peptone.

Question 85. The enzyme ptyalin helps to digest which type of food? From where is it secreted? 
Answer:
(1) Enzyme ptyalin helps to digest carbohydrate type of food.
(2) Ptyalin is secreted by salivary gland.

Question 86. Name any two amylolytic enzymes.
Answer:
(1) Amylase
(2) Maltase.

Question 87. What do you understand by digestion?
Answer: The breaking of complex, insoluble, and non-absorbable forms of food into simple, soluble, and absorbable forms with the help of enzymes is called digestion.

Question 88. What are the end products of digestion of proteins, carbohydrates, and fats in the case of man?
Answer:
(1) Proteins:— Amino acid.
(2) Carbohydrates:— Glucose, Fructose and Galactose.
(3) Fats:— Fatty acid and glycerol.

Question 89. State the function of gastric HCI.
Answer:
(1) It changes the medium of food in the stomach.
(2) It kills harmful germs.
(3) It activates pepsinogen to convert into pepsin.

Question 90. What is a Lacteal?
Answer: The blood vessels which is present within the villus and help in the absorption of fatty acid are called lacteal.

Question 91. What is peristalsis?
Answer: The movement of involuntary muscles of the alimentary canal which helps in the transfer of food in the forward direction is called peristalsis.

Question 92. Name one digestive juice devoid of enzymes. Name the food on which it acts regarding digestion.
Answer:
(1) Name of juice:— Bile
(2) Name of food:— Fat

Question 93. Name the bile salts.
Answer:
(1) Sodium taurocholate
(2) Sodium glycolate.

Question 94. Name the salivary glands of humans.
Answer:
(1) Parotid (below ear)
(2) Sub Maxillary (under lower gland)
(3) Sublingual (below tongue).

Question 95. Define assimilation and egestion.
Answer:
(1) Assimilation:-
The process by which the absorbed food substances are converted into protoplasm is called assimilation.

(2) Egestion:-
The process by which the animal body gets rid of the unabsorbed residue of food materials from the rectum through the anus is called egestion.

Question 96. What will happen when salivary glands are removed from the human body?
Answer: In the absence of salivary. glands saliva will not be formed in the mouth cavity. Carbohydrate digestion will not take place in the absence of the enzyme ptyalin which is a constituent of saliva. Some bacteria will not be destroyed in the absence of lysozyme.

Question 97. What type of food can be digested in the buccal cavity? Name any one of the glands which help in its digestion.
Answer:
(1) Carbohydrates type of food can be digested in the buccal cavity.
(2) The name of one gland that helps in carbohydrate digestion is the salivary gland (Ea. parotid)

Question 98. State one structural and one functional difference between villi and alveoli.
Answer:

Question 99. Explain the role of the liver in Digestion.
Answer: The liver cells produce bile. This is stored in the gall bladder. Bile reaches the duodenum through the bile duct. Enzymes are absent in bile. Despite this fact, bile takes part in digestion. First of all, it changes the medium of chyme which comes from the stomach to the duodenum. The salts present in bile emulsify fats into microscopic fat droplets.

Question 100. What is a vitamin?
Answer: The organic compounds which are mainly produced by plant cells but a small quantity of these substances are essential for the proper regulation of our metabolic reactions, are called vitamins.

Question 101. Name four fat-soluble vitamins.
Answer:
(1) Vitamin A
(2) Vitamin D
(3) Vitamin E
(4) Vitamin K

Question 102. What type of vitamins are thiamine and phylloquinone?
Answer:
(1) Thiamine:— Water soluble.
(2) Phylloquinone :— Fat soluble.

Question 103. What is the source of vitamin A? What type of disease occurs in its absence?
Answer:
(1) Source:- Green Vegetables.
(2) Disease:- Night Blindness.

Question 104. Name the vitamins which you are acquainted with.
Answer:
(1) Vitamin A
(2) Vitamin B
(3) Vitamin C
(4) Vitamin D
(5) Vitamin E
(6) Vitamin K.

Question 105. Deficiency of which vitamin causes Ricket? What is the source of this vitamin?
Answer:
(1) Vitamin D.
(2) Source:- Cod liver oil.

Question 106. Which vitamins are water soluble and which are fat soluble?
Answer:
(1) Name of water-soluble vitamins:— Vitamin B, Vitamin C.
(2) Name of fat-soluble vitamins:— Vitamin A, Vitamin D, Vitamin E, Vitamin K.

Question 107. What is the necessity o of vitamins? Mention the importance of vitamins.
Answer:
(1) Need of vitamins:-
Vitamins are necessary for the proper growth of different organs of the human body.

(2) Importance of vitamins:-
They regulate the metabolic reactions. Doing so they save us from different types of diseases.

Question 108. What is the source of vitamin C ? What disease is caused due to its deficiency?
Answer:
(1) Source:— Lemon, orange, amla.
(2) Disease:— Scurvy.

Question 109. Thiamine and Calciferol — What kind of vitamins are they?
Answer:
(1) Thiamine — Water soluble
(2) Calciferol — Fat soluble.

Question 110. What is Calciferol?
Answer: It is the chemical name of vitamin D.

Question 111. What is the P-P factor?
Answer: The full name is Pellagrea Preventing Factor. It is a water-like vitamin whose chemical name is Nicotinic acid and its deficiency causes pellagra.

Question 112. Which vitamin and which macro element are required for blood coagulation?
Answer: Vitamin K and macro element calcium are required for blood coagulation.

Question 113. What is the childhood metabolic bone disease associated with vitamin D deficiency? What is its adult counterpart?
Answer:
(1) Ricket is a childhood metabolic bone disease associated with vitamin D deficiency.
(2) The name of the disease that occurs in adults due to deficiency of vitamin D is ‘osteomalacia’.

Question 114. Mention any two functions of vitamin A.
Answer:
(1) It keeps eye-sight healthy.
(2) It helps in proper growth.

Question 115. Mention any one deficiency symptom for each vitamin ‘C’ and vitamin ‘D’ in man.
Answer:

Question 116. Mention the deficiency symptoms of Vitamin ‘E’ and Vitamin ‘K’.
Answer:

Question 117. Give the chemical name and source of Vitamin C.
Answer:
The chemical name of Vitamin C is ascorbic acid. Source of vitamin C ——
(1) Animal —— Adrenal cortex, Cow’s Milk
(2) Plant —— lemon, tomato.

Question 118. Classify vitamin K and vitamin C according to their solubility and deficiency disease.
Answer:
Vitamin K is soluble in fat and Vitamin C is soluble in water.

Deficiency disease:—
(1) Vitamin K ——— Haemorrhage
(2) Vitamin C —— Scurvy

Question 119. Write down two effects of the deficiency of vitamin ‘C’.
Answer:
(1) Scurvy —— Spongy and bleeding gums.
(2) Anaemia —The number of RBC and Platelets is reduced.

Question 65. What do you understand by essential macro elements?
Answer: The elements of which large quantity is required by living organisms for performing their different types of functions in their body are called essential macro elements.

Example:- Carbon, Hydrogen, Oxygen, etc.

Question 119. Name two trace elements that are essential for plant nutrition.
Answer:
(1) Copper (Cu)
(2) Zinc (Zn).

Question 120. Name any two of the non-metallic essential elements and state their respective sources.
Answer:
(1) Carbon:— CO₂
(2) Hydrogen:— H₂O

Question 121. In phosphorus (P) deficiency, what symptom is exhibited by the plant?
Answer: In phosphorus (P) deficiency leaves turn dark blue.

Question 122. What symptom is found in a plant due to a deficiency of Iron?
Answer: Due to a deficiency of Iron the color of leaves becomes yellow.

Question 123. What is the nitrogen deficiency symptom in plants?
Answer: Stunted growth and the lower portion of leaves become yellow.

Question 124. What is the source of the element Fe (Iron) in the case of human beings?
Answer: Fish is the source of the element Fe (Iron) in the case of human beings.

Question 125. In the absence of potassium which symptom is expressed in the case of a plant?
Answer: Leaves streaked with yellowish mottling at margins and tips.

Question 126. What is meant by chlorosis?
Answer: A plant disease that occurs mainly in leaves due to the deficiency of Iron (Fe), is called chlorosis.

Question 127. Name one macro element which is a major constituent of bones and teeth in animals. Name a disease in children caused due to the deficiency of that element.
Answer:
(1) The name of the macroelement is calcium.
(2) The name of the disease is Ricket.

Question 128. Name one macro element which is a major constituent of hemoglobin. Which disease is caused due to the deficiency of that element?
Answer:
(1) Name of macro element — Iron (Fe)
(2) Name of disease — Anaemia.

Question 129. Write one macro element and microelement each essential for the normal nutrition of plants.
Answer:
(1) Macro element — Nitrogen
(2) Micro element — Copper.

Question 130. Mention the role of magnesium in plant nutrition.
Answer:
Role of magnesium in plants:-
It is a component of chlorophyll. Hence, it takes part in chlorophyll formation. It acts as a co-enzyme of many enzymes.

Question 131. What is Basal Metabolic Rate?
Answer: The amount of energy spent by a living body per square meter per hour of body surface area at the time of complete physical and mental rest is called basal metabolic rate.

Value of BMR:—
40 K.cal/m?/hour. (in male), 37 Kcal/m2/hour (in females).

Question 132. What is the daily total average calorie requirement for an adult human male?
Answer: The daily total average calorie requirement for an adult human male is 3000 — 3400 Calories.

Question 133. What is a balanced diet?
Answer:
Balanced diet:-
A diet in which all the nutrients (such as carbohydrates, proteins, fats, minerals, vitamins, and water) are present in proper proportions is called a balanced diet.

Question 134. What is Diet?
Answer: A prescribed course of nutrients, which provides all requirements for the normal functioning of our body is called a diet.

Question 135. Define metabolism.
Answer: All cellular biochemical reactions leading to the synthesis of complex substances in the body using simpler substances with the help of energy and the breakdown of
complex substances to simpler substances together with the liberation of energy are called metabolism.

Question 136. Name the types of metabolism.
Answer:
There are two types of metabolism :
(1) Anabolism
(2) Catabolism.

Question 137. What do you mean by anabolism?
Answer: Cellular biochemical processes involved in the synthesis of complex molecules by using simpler substances and energy are called anabolism.

Ex. Photosynthesis.

Question 138. What do you mean by catabolism?
Answer: Cellular biochemical processes that are involved in the breaking of complex molecules into simpler substances with the liberation of energy are called catabolism.

Example — Respiration.

Question 139. Nitrogen is a very essential element for the nutrition of living beings.
Answer: Nitrogen takes part in the formation of living material like protoplasm, protein, hormone,s and enzymes.

Question 140. Why does one suffer from goiter?
Answer: Due to a deficiency of the ‘Iodine’ element in their diet, the persons suffering from goiter.

Question 141. Write two reasons why enzymes are called organic Bio-catalysts.
Answer:
(1) Enzyme is protein by nature and produced within living cells.
(2) Enzyme never starts the reaction, only increases or decreases the rate of reaction.

Question 142. Why do we take food?
Answer: We take food to obtain energy which is used to perform various metabolic functions and body activities. We take food for the growth and development of our
body also.

Question 143. Why is calcium necessary for us?
Answer: Calcium takes part in the formation of bone. It is also essential for blood clotting and muscle contraction.

Question 144. Why is phosphorus necessary for us?
Answer: Phosphorus takes part in the formation of ATP, bones, and teeth.

Question 145. Why does the food undergo digestion before absorption in our alimentary canal?
Answer: The process of digestion changes the complex food into a simple soluble form. Only simple and soluble substances are absorbed.

Question 146. Why is milk not considered a balanced diet for adults?
Answer:
Milk is not considered a balanced diet for adults due to the following reasons:—
(1) Presence of water in excess quantity
(2) Lack of Iron
(3) Absence of roughage
(4) Presence of vitamins in less quantity.

Question 147. Why do we lose weight during starvation?
Answer: Nutrients are not available to the cell during this period from outside. Cells obtain nutrients from the reserve stock. Reserve stock of food is gradually used up. So we lose weight during starvation.

Question 148. ‘All foods are nutrients but all nutrients are not foods’ — Why?
Answer: The essential organic and inorganic substances collected from nature that perform the basic activities of living organisms are called nutrients.

The nutrients which are organic edible substances that produce energy and provide material for growth are called food.

Therefore, all foods are nutrients but all nutrients are not foods.

Question 149. Why is glucose called the starting point of respiration?
Answer: Glucose is called the starting point of respiration because it is the end product of carbohydrate digestion. Its oxidation takes place within a cell. It starts the process of
respiration within the cytoplasm of the cell.

Question 150. What is the relationship between nutrition and circulation?
Answer: Nutrition:-
The total of the processes like ingestion, digestion, absorption, assimilation, and egestion is called nutrition.

Circulation:-
The translocation of various substances like digested food, minerals, vitamins, gases, excretory substances hormones, etc. through a liquid medium is called circulation.

Relation:-
Glucose, amino acids, and fatty acids are produced by the process of digestion. They reach the bloodstream by the process of absorption. These substances are supplied to different cells by the process of circulation. Thus nutrition provides the raw materials for circulation and circulation helps in the distribution of nutrients which are essential for the completion of its stages like assimilation.

Question 151. Write one structural and one functional difference between red blood cells and white blood cells.
Answer:

Question 152. Mention two functions of hemocyanin.
Answer:
(1) It carries oxygen gas from respiratory organs to tissue.
(2) It carries carbon dioxide gas from tissue to the respiratory organ.

Question 153. Mention the role of blood in protecting the human body from germs causing diseases.
Answer: The white blood corpuscles kill the germs by their phagocytic activity. Gamma globulin of plasma protein forms antibody which also protects the body.

Question 154. What is circulation? 
Answer: The transportation of substances like digested food, gases, excretory products, mineral salts, and hormones through a liquid medium from one part of the body to other parts of the body, is known as circulation.

Question 155. What is the circulatory system?
Answer: A group of organs that are involved in completing the process of circulation is called the circulatory system.

Question 156. Name the different components (organs) of the blood circulatory system in the human body.
Answer:
(1) Heart
(2) Blood vessels (artery, vein, and capillary)

Question 157. What is blood?
Answer: Blood is a fluid connective tissue.

Question 158. What is pure blood?
Answer: The blood that contains sufficient oxygen is called pure blood.

Question 159. Name any one type of White Blood Corpuscles (W.B.C) and state its function.
Answer:
(1) Basophil.
(2) Function
It helps in the formation of ‘heparin’

Question 160. Name two components of mammalian blood besides plasma.
Answer:
(1) R.B.C.
(2) W.B.C.

Question 161. What is the function of hemocyanin?
Answer: It carries oxygen gas and carbon dioxide gas.

Question 162. What is the function of red blood corpuscles? Is there any nucleus present in human R.B.C.?
Answer:
1. Function:-
(1) It carries hemoglobin.
(2) It maintains the viscosity of blood.

2. No.

Question 163. What is the percentage of hemoglobin in human blood and name the disease that occurs if the percentage falls?
Answer:
(i) 95% — 115%.
(ii) Anaemia.

Question 164. What is a thrombocyte?
Answer: The non-nucleated blood cells that are produced by ‘mega karyocytes’ of the bone marrow are called thrombocytes.

Question 165. Name the respiratory pigment found in the blood of vertebrates. What is the function of that respiratory pigment?
Answer:
(1) Haemoglobin.
(2) It carries oxygen gas and carbon dioxide gas.

Question 167. Mention two functions of W.B.C.
Answer:
(1) To destroy harmful bacteria.
(2) To produce heparin’.

Question 168. Blood is red – Why?
Answer: Blood is red because it contains hemoglobin, an iron-containing pigment.

Question 169. What is the function of thrombocytes?
Answer: To produce an enzyme. (Ex. Thrombokinase), it helps in blood clotting.

Question 170. How many types of blood groups are found in man? What are those groups?
Answer:
(1) Types of blood groups – 4
(2) Name of blood groups – A, B, AB, O.

Question 171. How many chambers are there in the heart of a man?
Answer: 4 (Right auricle, Right ventricle, Left auricle, Left ventricle) chambers are present in the heart of a man.

Question 172. What is a tricuspid valve?
Answer: A set of three cusps valves located between the right auricle and right ventricle is called a tricuspid valve.

Question 173. What do you mean by blood groups?
Answer: The types of human blood, the classification of which is done based on ‘antigen’, are called blood groups.

Question 174. What is blood coagulation?
Answer: The bio-chemical process that occurs at the injured part of the body and due to which fluid blood is changed into solid and checks the oozing of blood is called blood
coagulation.

Question 175. What is meant by Immunity?
Answer: The ability of living organisms they protect themselves from the harmful effects of the chemicals or germs is known as ‘Immunity’.

Question 176. Mention two characteristics of blood as connective tissue.
Answer:
(1) A connective tissue has a matrix. In blood, the matrix is found. Hence blood is a connective tissue.
(2) A connective tissue connects the different parts of the body. Blood also connects the different parts of the body, so blood is a connective tissue.

Question 177. In which way CO_{2 CO2-rich} blood transported to the lungs from the human heart?
Answer: Through the pulmonary artery from the right ventricle, CO2-rich blood is transported to the lungs from the human heart.

Question 178. What are the functions of the right auricle and left ventricle in the human heart?
Answer:
(1) Function of the right auricle:-
It receives deoxygenated blood from the vena cava and supplies it to the right ventricle.

(2) Function of the left ventricle:-
It receives oxygenated blood from the left auricle and supplies this blood to the aorta.

Question 179. What do you mean by open circulation? Give one example.
Answer: The type of circulation in which blood flows within the sinuses of the body so that the internal parts are in direct contact with blood, is called open circulation.

Ex. Cockroach.

Question 180. What do you mean by closed circulation? Give one example.
Answer: The type of circulation in which blood flows only within blood vessels is called closed circulation.

Ex. Man.

Question 181. Mention the mediums of transport in animal and plant bodies.
Answer:
(1) In Animal Bodies – Blood and Lymph.
(2) In Plant bodies – Water.

Question 182. What are the functions of the left auricle and right ventricle in the human heart?
Answer:
(1) Function of the left auricle:-
It receives oxygenated blood from the lungs through two pairs of pulmonary veins and sends it to the left ventricle.

(2) Function of the right ventricle:-
It receives Deoxygenated blood from the right auricle and sends it to the lungs through the pulmonary artery.

Question 184. What is Blood Pressure? Name an instrument used to measure this.
Answer:
(1) Blood Pressure:-
The pressure exerted on the walls of blood vessel (Artery)
by the blood during its flowing is called blood pressure.

(2) Name of instrument:-
Sphygmomanometer.

Question 185. What is Antigen and Antibody?
Answer:
Antigen:-
Any foreign material like germs, abnormal proteins, etc. which gets entry into the body is termed an: antigen.

Antibody:-
The organic substances that are chemically protein in nature and produced within the cytoplasm of the cell in response to antigens are called antibodies.

Question 186. What is the main function of the heart?
Answer: To collect deoxygenated blood from the superior and inferior vena cava and oxygenated blood from the lungs and distribute the oxygenated blood to different organs
of the body.

Question 187. What are Lymphocytes? Write their functions.
Answer: They are non-granular leucocytes. (W.B.C.).

Function:-
They produce antibodies.

Question 188. What do you mean by systole and diastole?
Answer:
Systole:-
The contraction of the heart is called Systole.

Diastole:-
The expansion (Relaxation) of the heart is called diastole.

Question 189. What is the normal amount of hemoglobin present in the blood of an adult man?
Answer: 14.5mg / 100 milliliter is the normal amount of hemoglobin present in the blood of an adult man.

Question 190. What is Capillaries?
Answer: The place of blood vessels from where the exchange of GIeF and the nature of substances takes place is called Capillaries.

Question 191. What do you mean by universal donor?
Answer: The group of blood that is transfused to all groups of blood safely is called a universal donor.

Ex. O blood group.

Question 192. What do you mean by universal recipient?
Answer: The group of blood that can receive all types of blood is called the universal recipient.

Ex. AB group blood.

Question 193. What is the function of the right auriculo—ventricular valve in man?
Answer: The right auriculoventricular valve allows blood to enter only into the right ventricle from the right auricle. It does not allow blood to return from the right ventricle to the right auricle.

Question 194. Which chambers of the human heart are known as the receiving part and which chambers are known as the forwarding part of blood circulation through the heart?
Answer: Receiving part — Right auricle and Left auricle.
and Forwarding part — Right ventricle and Left ventricle.

Question 195. State two different systemic veins and portal veins.
Answer:

 

Question 195. What is double circulation?
Answer: The process of circulation which occurs in four chambers containing the heart is called double circulation.

Ex – man

Question 196. Write one structural and one functional difference between the bicuspid and the tricuspid valve.
Answer:

Question 197. Name the vein that carries oxygenated blood. From which part does it carry this blood and to where?
Answer:
(1) Plumonary Vein.
(2) From lungs to left auricle.

Question 198. Name the blood vessel entering the kidney and the type of blood that flows through it.
Answer:
(1). Renal artery.
(2) Urea containing blood.

Question 200. Define venous heart with an example.
Answer: One auricle and one ventricle containing a heart in which always deoxygenated blood is flowing, is called a venous heart.

Ex — Fish heart.

Question 201. Name two main respiratory pigments in animals.
Answer:
(1) Haemoglobin
(2) Haemocyanin.

Question 202. Write two reasons for the non-coagulation of blood within the blood vessels in normal conditions.
Answer:
Reasons:-
(1) Presence of heparin.
(2) Presence of intact thrombocytes

Question 203. When any part of our body is cut, why doesn’t the entire blood come out from it?
Answer: Because blood forms a clot at that place, which prevents the blood from coming out.

Question 204. Why is blood transfusion not always possible from one person to another?
Answer: Because the antigens of the donor blood do not match with the antibodies of the recipient blood. In this case, a clump is formed which blocks the blood vessels
of the recipient.

Question 205. Why does blood not clot while flowing through the vessels?
Answer:
(1) Due to the presence of an anticoagulant substance (e.g. Heparin) in the blood of blood vessels.
(2) Due to the smooth inner wall of blood vessels.
(3) Thromboplastin which is necessary for blood clotting is not produced by intact thrombocytes.

Question 206. Why is Land Steiner famous?
Answer: Land Steiner discovered the blood group.

Question 207. Why is it necessary to know an individual’s blood group?
Answer: For the safe transfusion of blood to the needy person in case of accident or other cases. It is also necessary for the selection of a proper matching pair to avoid fatal cases.

Question 208. Why is the heart of a fish called the venous heart?
Answer: A fish heart has one auricle and one ventricle. Deoxygenated blood flows within it. Hence its heart is called a venous heart.

Question 209. Why is the blood of a cockroach colorless?
Answer: The blood of the cockroach is colorless because respiratory pigments are absent in it.

Question 210. Why is the color of the plasma slightly yellow?
Answer: The color of plasma is slightly yellow due to the presence of some compounds. Such as bilirubin.

Question 211. Why do birds and mammals have separate oxygenated and deoxygenated blood?
Answer: The rate of anabolism is higher in birds and mammals they need more oxygenated blood to produce energy by the process of respiration. Their heart is made of four chambers. So, the oxygenated and deoxygenated blood do not mix. The structure of the heart helps supply oxygenated blood to the body.

Chapter 3 Heredity And Common Genetic Diseases Short Answer Questions

Question 1. Mention two criteria for classifying a mineral into macronutrients.
Answer:
(1) These elements are present in larger quantities (1-10 mg per gram dry weight of plants).
(2) They are mainly involved in the synthesis of structural components of the plants.

Question 2. Mention two criteria for classifying a mineral into a micronutrient.
Answer:
(1) These elements are present in minute quantities (0.1 mg or less per gram dry weight of plant) and are also known as trace elements.
(2) High concentrations of ‘micronutrients may prove to be toxic.

Question 3. How do minerals help in the formation of protoplast?
Answer: Formation of protoplast: Various mineral elements, such as C, H, O, S, Mg, P, N, and Fe, play a prominent role in the formation of chemical constituents of protoplasm.

Question 4. Which minerals help in the growth of plants?
Answer: Growth: Mineral elements, such as Zn, Mn, B, etc. maintain normal growth of stem and root.

Question 5. Mention two points of importance of phosphorus in plant nutrition.
Answer:
Phosphorus (P) :
(1) Plays an important role in protein synthesis.
(2) Acts as a component of ATP, NADP, and membrane of cells & other organelles.

Question 6. Mention two points of importance of iron in plant nutrition.
Answer:
Iron (Fe) :
(1) Helps in the formation of chlorophyll & chromatin reticulum.
(2) Acts as a structural element of electron carriers & helps in ion transport.

Question 7. What is transpiration?
Answer: The elimination of non-utilized excess water in the form of vapor from the plant body, under the influence of sunlight, and controlled to some extent by protoplasmic called transpiration.

Question 8. Draw and label a structure of stomata.
Answer:

Question 9. What is evaporation?
Answer: Evaporation is a physical process in which water changes from a liquid to a gaseous form, i.e., vapor, to the unsaturated atmosphere from the free exposed surfaces of the living and non-living bodies.

Question 10. State how light influences transpiration. 
Answer: Light — Transpiration increases in the presence of light and decreases in the absence of light, as stomata open during the day and close during the night. Light influences transpiration by increasing the temperature of the leaf.

Question 11. What is cuticular transpiration?
Answer: Cuticular transpiration — The water vapor which is lost through the pore of the cuticle of the leaves directly, is called cuticular transpiration. Some amount (10-20%) of water vapor is lost by direct evaporation from the epidermal cells through the cuticle of the leaves. Structure of cuticle.

Question 12. Draw and label a structure of lenticel.
Answer:

13. What is diffusion?
Answer:
Diffusion :
Diffusion is defined as a physical process where molecules or ions migrate from a region of higher concentration to a region of lower ‘concentration, through liquid or gaseous medium by. their random motion.

Question 14. What is root pressure?
Answer: This active hydrostatic pressure created in the parenchymatous cortical cells of the roots is called the root pressure. val.

In the year 1956, Stocking defined root pressure “as a pressure developing in the tracheary elements of the xylem as a result of the metabolic activities of roots.”

Question 15. What is transpiration pull?
Answer:
Transpiration Pull :
During this a pull is created due to an increased concentration of cell sap, this pull over the water molecule forming pillar, due to transpiration is called transpiration pull.

Question 16. State the relation between absorption and ascent of sap.
Answer: Relation between Absorption and Ascent of Sap: Unicellular root hairs absorb water and minerals (capillary water and minerals) from the soil. This water enters the cortical cells by cell-to-cell osmosis and diffusion. Hydrostatic pressure exerted by these turgid parenchymatous cortical cells helps the water to enter the xylem vessels. The transpiration pull from the leaves and the root pressure from below accounts for the ascent of sap through the xylem vessels. The continuity of the water column is maintained by the cohesion of water molecules with each other and the adhesion of water molecules with the xylem vessel wall.

Question 17. What do you mean by cohesion and adhesion?
Answer:
(1) Adhesion — Adhesion is the molecular attraction exerted between the surface of bodies in contact, i.e., the union between water molecules with the inner xylem vessel wall.
(2) Cohesion — Cohesion is the molecular attraction by which the particles of a body are united throughout the mass, i.e., the union between water molecules.

Question 18. What do you mean by permeable membrane?
Answer: Permeable membrane — Such membrane allows all the molecules or ions of a solution (both solute and solvent molecules) to pass through it, e.g. filter paper, cell
wall, etc.

Question 19. What do you mean by semipermeable membrane?
Answer: Semipermeable membrane — Such membrane allows passage of water (solvent) molecules and positively charged hydrogen ions, but on the solute molecules nor the other positively charged and negatively charged particles, e.g. parchment
paper, air bladder of fish, egg’s membrane, etc. The semipermeable membrane can be better termed as differentially permeable, which allows the passage of some solutes but holds back others at different rates of diffusion.

Question 20. What do you mean by plant circulation?
Answer: The process by which movement of food, water, minerals, hormones, enzymes, and other substances takes place through the liquid medium of the living body by special conducting tissues xylem and phloem, is called plant circulation.

Question 21. What is osmosis? 
Answer:
Osmosis :
Osmosis is defined as the physical process in which solvent molecules move from the region of higher concentration to the region of lower concentration through a semipermeable membrane, separating these two.

Question 22. Mention the role of water and sunlight in photosynthesis. Write the overall reaction of this process. Mention the role of photosynthesis in maintaining the balance of CO₂ and O, in air.
Answer:
Role of water in the process of photosynthesis:—
Water is a raw material for photosynthesis. It is essential for this process. It supplies hydrogen for the reduction of CO2. Thus it takes part in glucose formation. The oxygen of water is changed into the free form of oxygen gas which comes out through the stomata.

Role of sunlight in photosynthesis :
The intensity, quality, and duration of Light influence the rate of photosynthesis. The light activates chlorophyll. Activated chlorophyll performs photolysis. Too much high-intensity light may even stop the process of photosynthesis. The inhibition of photosynthesis due to high-intensity light
which slows down its rate is called solarization. The rate of photosynthesis is directly related to the duration of light.

Equation :- 6CO₂ + 12H₂O→ C₆H₁₂O₆ + 6H₂O + 6O₂

Role of photosynthesis in maintaining the balance of CO₂ and 0, in the environment:—
The percentage of CO₂ and O₂ gas in (air and water) is maintained by photosynthesis. Autotrophs take in CO₂ gas from their environment for the process of photosynthesis. They liberate O₂ gas during this process. All living organisms take in O₂ gas and release CO₂ gas during respiration. Thus photosynthesis and respiration in a combined effect maintain the balance of CO₂ and O₂ in the environment.

Question 23. What is photosynthesis? Discuss the importance of the process of photosynthesis in the entrapping of solar energy in green plants and the maintenance of CO₂ — O₂ balance in the environment.
Answer:
Photosynthesis :
The anabolic reaction that occurs between carbon dioxide
gas and water in the presence of sunlight and chlorophyll to produce glucose is known as photosynthesis.

Equation :- 6CO₂ + 12H₂O→ C₆H₁₂O₆ + 6H₂O + 6O₂

Importance of Photosynthesis:—
(1) In the entrapping of solar energy in green plants:—
The sun’s radiant energy is the only source of energy for all the living organisms of this biosphere. But this form of energy is directly utilized by green plants only. Chlorophyll which is a photosynthetic pigment only present in the grana region of the chloroplast of plant cells. Chlorophyll molecules absorb the radiant energy and change it into activated chlorophyll which splits water molecules into H⁺ ions and OH^– ions and begins the process of photosynthesis. At the end of this process, the radiant energy is finally converted into chemical energy. This chemical energy is stored within glucose molecules. All other organisms obtain their energy from this glucose directly or indirectly. Thus by entrapping radiant energy during photosynthesis green plants supply chemical energy to the other forms of life.

(2) Maintenace of CO₂ and O, balance in the environment:—
The percentage of CO₂ and O₂ gas in (air and water) is maintained by photosynthesis. Autotrophs take in CO₂ gas from their environment for the process of photosynthesis. They liberate O₂ gas during this process. All living organisms take in O, gas and give out CO₂ gas during respiration. Thus photosynthesis and respiration in a combined effect maintain the balance of CO₂ and O₂ in the environment.

Question 24. Explain the following reaction  6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂  Where does the process related to the above reaction occur? Explain the significance of that process.
Answer:
1. Facts obtained by the reaction:-
(1) This reaction takes place in the presence of sunlight and chlorophyll.
(2) Carbon dioxide and water are reactants.
(3) Glucose, oxygen, and water are products.
(4) 6 molecules of carbon dioxide combine with 12 molecules of water to produce one molecule of glucose, 6 molecules of oxygen, and 6 molecules of water.
(5) Here water is oxidized to produce free oxygen and carbon dioxide is reduced to produce glucose.

2. This reaction occurs in the Grana and stroma region of the chloroplast of a plant cell.

3. Significance of photosynthesis:—
(1) Solar energy is entrapped and converted into chemical energy by this process. This chemical energy is stored within food (ex. glucose). This food is the source of energy for all living Autotrophs and Heterotrophs.
(2) CO, and O, balance is maintained by this process.

Question 25. Mention two differences between photosynthesis and respiration. Discuss the roles of sunlight and chlorophyll in the process of photosynthesis.
Answer:
(1) Two differences between photosynthesis and respiration:—

(2) Role of sunlight in photosynthesis:—
The intensity, quality, and duration of influences the rate of photosynthesis. Photolysis of water occurs in the presence of light. Too much high-intensity light may even stop the process of photosynthesis. The inhibition of photosynthesis due to high-intensity light which slows down its rate is called solarization. The rate of photosynthesis is directly related to the duration of light.

 

(3) Role of chlorophyll in photosynthesis:—
Chlorophyll is a magnesium-containing green pigment present in the chloroplast of green plants. The chlorophyll pigment first absorbs the incoming solar radiation. It results in the activation of the chlorophyll. Activated chlorophyll causes the dissociation of water. Hence chlorophyll helps in the photolysis of water.

Question 26. Describe briefly the process of photosynthesis.
Answer:
Process of Photosynthesis:—

The process of photosynthesis is completed in two main phases:—
Light Phase:—
This is the 1st phase of photosynthesis. It occurs in the grana
region of chloroplast. Light energy is necessary for the beginning of this phase.

This phase is divided into two parts:—
(1) Photolysis of water:—
When sunlight falls on the surface of the green leaves of plants, some part is absorbed by chlorophyll molecules, and the remaining part is reflected from the surface to the environment. The chlorophyll molecules are changed into activated chlorophyll after the absorption of light. Activated chlorophyll splits water molecules into H⁺ ions and OH ions. OH^– ion loses one electron and is converted into OH radical. This OH radical is changed into water and oxygen gas. Water again takes part in metabolic reaction and oxygen comes out to the environment through stomata. H⁺ion gains one lost electron of OH^– ion and is changed into a neutral hydrogen atom. It combines with NADP (Nicotinamide Adenine
Dinucleotide Phosphate) and reduces it into NADPH, At the end of this reaction, the activated chlorophyll molecule resumes its original state.

(2) Photophosphorylation:—
The tet formation of ATP in the presence of sunlight by Ree the combination of ADP and inorganic HeOGyatcy, Oe phosphorus is called photophosphorylation.

Dark reaction:-
This is the second and last phase of photosynthesis. It occurs in the stroma region of the chloroplast. It takes place after 1/1000th second of the end of the light phase. Light energy is not necessary for the beginning of this phase.

Ribulose Diphosphate (5-carbon organic compound) is already present in the stroma region. It combines with CO₂ and forms a six-carbon unstable compound (C₆H₁₂O₁₃P₂,).

This unstable compound forms two molecules of the 3-carbon compound in a very short interval of time. The name of this 3-carbon compound is phosphoglyceric acid (PGA). It reacts with ATP and is converted into 1, 3 Diphosphoglyceric Acid (PGA).

DiPGA reacts with NADPH₂ and forms 3, Phosphoglyceraldehyde (PGAID). Now the two molecules of phosphoglyceraldehyde react and form one molecule of Fructose Siphosphate.

Fructose Diphosphate forms one molecule of glucose phosphate and in the last one molecule of glucose is produced from one molecule of glucose phosphate.

Light Phase:
(1) Sunlight →Chlorophyll → Activated chlorophyll
Activated Chlorophyll → H₂O →H⁺  + OH^–
NADP + 2H = NADPH₂, 4OH + 2H₂O + O_{2
ADP + iP + energy = ATP}

Dark Phase:
RuDP + CO₂ = 6 carbon unstable compound
5C         1c
6 carbon unstable compound →2 molecules of PGA

(3C)
PGA + ATP > DiPGA (3C)
DiPGA + NADPH, → PG.Ald. (3C)
2DipGAld — Fructose Diphosphate
Fructose Diphosphate — Glucose phosphate
Glucose phosphate — Glucose.

Question 27. Write a short note on the role of photosynthetic pigments in the process of photosynthesis.
Answer: Pigments — Chlorophyll and Carotenoids 3 The main photosynthetic pigment is chlorophyll.

Role — The photolysis of water during the light phase of photosynthesis is caused by excited chlorophyll molecules. The cause of their excitation is the absorption of highly energized invisible solar particle photons. H₂O → H⁺ (Hydrogen ion) + OH^– (Hydroxyion).

The entrapping of solar energy and its conversion to Genie energy in the form of ATP (Adenosine tri-phosphate) is carried out by activated chlorophyll molecules.

Plant pigments :
Plants may contain two types of piel seins green coloured ee chlorophyll and yellowish orange coloured carotenoid.
(1) Chlorophylls are of two types—Chlorophyll a(C₅₅H72O₅N₄Mg) and Chlorophyll b(C₅₅H70O₆N₄Mg), Chlorophyll c, d and e are also present. Chlorophyll atoms are arranged in a circle with the help of four pyrrole rings with the Mg atom at the center. Along with the pyrrole ring is attached phytol (a type of alcohol).
(2) Carotenoids are of two types—Carotene (C₄₀H₅₆)—the orange-colored can’t Xathophyll. (C₄₀H₅₆O₂)—the yellow-colored pigments.
(3) Phycocyanin — the blue colored and Phycoerythrin — the lavender rec colored pigments.

II. Carotenoids :
Carotenoids are yellow, brown, orange, or yellow pigments found in close association with chlorophylls in all photosynthesizing cells. They occur in thylakoids and act as accessory pigments of photosynthesis. They are present in nearly all higher plants, algae, and some microorganisms. Goodwin (1960) suggested that the chlorophylls and carotenoids may be attached to the same protein, forming a complex known as phosynth.

Carotenoids are of two types:
(1) Carotenes — They are orange to yellow and are unsaturated hydrocarbons (C₄₀H₅₆). They are insoluble in water but readily soluble in chloroform ether and carbon disulfide. They absorb blue and green lights and transmit yellow and red lights. Four isometric forms of carotenes are now recognized. α, β, γ, and δ of which β-carotene is most common in all green plants.
(2) Xanthophylls or Carotenols — They are yellow with the empirical formula C₄₀H₅₆O₂. In normal green leaves, proportionately there is more xanthophyll than carotene. The most common xanthophyll in green leaves is luteol or lutein.

Apart from their role in the absorption of light energy and its transfer to chlorophyll, the carotenoids play a very important role in protecting chlorophyll molecules from
photo-oxidation within the photosynthetic apparatus.

Question 28. Write a short note on the absorption and action spectra of photosynthesis.
Answer:
Absorption Spectrum :
All organic substances absorb light, but colored pigments absorb only visible light. The absorption spectrum is the pattern of absorption of light at the different wave, lengths by the object. Studying the absorption spectrum of chlorophyll a and b, it is revealed that these pigments absorb red and blue regions of spectra chiefly.

The plot of efficiency with which the different pigments like chlorophyll-a and chlorophyll-b absorb different wavelengths (or color) of light in the region of blue-violet, with peaks about 429 and 453 m µ respectively and the next maximum is in the red region of about 642 m µ and 660 m µ respectively, is called the absorption spectrum.

The carotenoid pigments play a role in photosynthesis by absorbing light and passing it to chlorophyll where it is used in the photosynthetic process.

Absorption spectra are one of the properties of chlorophyll, during which they can absorb certain wavelengths of light. When the chlorophyll solution is kept in between ordinary light and a spectrometer, then it is observed that certain wavelengths of light are absorbed more than others. Maximum absorption of chlorophyll-a and chlorophyll takes place in the blue-violet region and the next maximum in the red region.

Action spectrum of photosynthesis :
When a beam of sunlight is passed through a glass prism the following colors are visible- violet, indigo, blue, green, yellow, orange, and red. The above component colors of light possess their range of wavelength. By utilizing the above component wavelengths of white light, it is possible to find out which wavelengths or colors of light help to run the process of photosynthesis most effectively and efficiently. A pattern can be drawn without any trouble by plotting the effectiveness of each wavelength of light that stimulates photosynthesis. Such a plot of the photochemical effect caused by equal energies of various wavelengths of light is called an action spectrum. This spectrum shows that blue and red light regions of the spectrum help to run the photosynthetic process more effectively.

Question 29. Write a short note on the site of photosynthesis.
Answer:
Site of photosynthesis :
The process of photosynthesis occurs within the chloroplastids of the mesophyll cells of green leaves. It also occurs in the chlorophyllous tissue of green-colored young stems, calyx of flowers, phylloclade of cacti fruit coat of young fruits, and aerial roots of orchids. It may also occur in lower plants like algae, bryophytes, and photosynthetic bacteria. It even occurs in the cells of certain protozoa, like Chrysamoeba and Euglena.

The leaves are the best site for photosynthesis. These are flattened structures having more surface area for trapping greater amounts of solar energy and absorbing CO₂  from the air. Closely arranged cells of mesophyll tissue, which are the site of photosynthesis, are present in the leaves.

Question 30. Define nutrients. Differentiate between macro and micronutrients.
Answer: The organic and inorganic materials that provide energy to the body and keep the body in good and healthy condition are called Nutrients. All nutrients are food, but all foods are not nutrients.

Question 31. What are the general functions of essential mineral elements?
Answer:
(1) Formation of protoplast — Certain elements play an important role in the formation of constituents of protoplasm like C, H, O, N, S, etc.
(2) Structure of enzymes — Elements like C, H, O, N, Mg, Fe, Zn, and Cu are involved in the formation of enzymatic components and their functions.
(3) Oxidation — Reduction reaction — elements like Iron and copper take part in electron transfer.
(4) Gsmotic balance — Inorganic salts in the cell sap like Cl^–, K⁺, PO₄^-3, and SO₄^-2 are involved in maintaining the osmotic balance of the cell.
(5) Formation of chlorophyll — Magnesium is the chief component of chlorophyll.
(6) Buffer effect — Phosphate, bicarbonate, and carbonate act as buffers.

Question 32. Mention the functions of macro- and micro-elements in plants.
Answer:
(1) Potassium –      Regulates intracellular fluid volume. Permeability of cell membrane Chlorophyll synthesis.  Activator for many enzymes.
(2) Calcium  –        Constituent of middle lamellas up.  An important role in ion transport. Act as an activator for enzymes.
(3) Carbon  –         Constituent of protoplasm, cell wall, and cell materials.
(4) Oxygen stra –   Required for aerobic respiration
(5) Nitrogen –        Constituent of protoplasm and almost all cellular materials, amino acid, protein, enzymes, nucleic acid, etc.
(6) Hydrogen –      Constituent of protoplasm
(7) Sulphur –          Constituent of protoplasm, some protein and vitamins.
(8) Phosphorus –   Constituent of protoplasm, Nucleic acid, Nucleoprotein, Phospholipid, etc.
(9) Magnesium –   Constituent of chlorophyll, an activator of many enzymes of photosynthesis, respiration, and nucleic acid synthesis.
(10) Manganese an important role in chlorophyll synthesis, and activates many respiratory enzymes.
(11) Boron –           Help in translocation of sugar, active salt absorption, Murillo
(12) Copper –         Constituent of oxidizing and reducing enzymes highly toxic in higher concentrations.
(13) Molybdenum – A component of enzyme, plays an important role in nitrogen metabolism.
(14) Zinc –              Required for synthesis of auxin IAA.

Question 34. What is the significance of nutrition?
Answer:
Significance or Importance of Nutrition:
(1) promote growth, repair wear and tear of the damaged tissues, and gain energy to control the different metabolic processes are the main functions of nutrition.
(2) Through nutrition the potential energy stored within food is transformed into usable energy. The different physiological functions of the living body like movement, locomotion, excretion, reproduction, etc. are controlled by utilizing this energy.
(3), Through nutrition the disease-resistant power of the living body is developed.
(4) Through nutrition future food matters are stored within the living body. From those stored food (in the plant body mainly as starch and in animals as glycogen and fat) the future energy is produced during shortage of food.
(5) Nutrition plays a special role in the production of heat energy in the animal body to meet the caloric demands of an individual.

Question 35. Mention the general functions of essential mineral nutrients in plants.
Answer: The general functions of essential mineral nutrients are —
(1) Formation of protoplasm :
The formation of a major part of the protoplasm in a living cell needs mineral elements like carbon, hydrogen, and oxygen. Nitrogen, sulfur, and phosphorus also take part in the formation of protoplasm.

(2) Structure of enzyme :
Some mineral nutrients act in the formation of the structure of enzymes (act as catalysts) in many precursors. Some mineral elements like magnesium, ‘manganese, cobalt, etc. perform the functions of activators on inhibitors in the system of enzymes. Phosphorus helps in the formation of coenzymes like NAD, NADP, FAD, ATP, etc. Mg, S, and K, ct as an activator of enzymes.

Copper is a component of certain enzymes (i.e., phenolases, laccase, and ascorbic acid) oxidases sulfur contains coenzyme A. Calcium is an essential part of amylase, an enzyme that helps in starch digestion. Iron is noted in enzymes like peroxidases and catalases. Manganese helps in the formation of the enzymes decarboxylate and oxidase is citric acid.

(3) Oxidation-reduction reaction :
Oxidation is simply regarded as a chemical reaction with oxygen (loss of electrons). The reverse process of loss of oxygen is called reduction. Reaction with hydrogen is also regarded as reduction (gain of electrons).

(4) Osmotic balance :
Certain mineral nutrients counteract the poisonous effect of some other elements by maintaining the osmotic balance (an ionic balance). The behavior of one ion in reversing the normal effect of another ion is called antagonism. To this group of elements lies Ca, Mg, and K. They are termed balancing elements, whereby osmotic balance is maintained.

(5) Formation of Chlorophyll :
Magnesium and nitrogen play a great role in the formation of chlorophyll, the green pigments in plants. Iron takes part in chlorophyll synthesis.

(6) Buffer effect :
The effect produced when a solution resists change in pH when an acid or alkali is added or when the solution is diluted is called the buffer effect.

The mineral nutrients play a great role in the pH of all sap. Some of the vital buffer systems in an organism’s body are the carbonate-bicarbonate system and phosphate
buffer.

Question 36. What are the criteria for classifying mineral nutrients into macronutrients? and micronutrients?
Answer: To categorize mineral nutrients as macronutrients or micronutrients, they should fulfill certain criteria. These criteria are discussed below.

Criteria for macronutrients :
(1) These elements are present in larger quantities (1-10 mg per gram dry weight of plants).
(2) They are mainly involved in the synthesis of structural components of the plants.
(3) They also participate in maintaining the osmotic potential of the plants.

Criteria for micronutrients :
(1) These elements are present in minute quantities (0.1 mg or less per gram dry weight of plant) and are also known as trace elements.
(2)High concentrations of micronutrients may prove to be toxic.
(3) They participate in the electron transport mechanism and act as cofactors for various enzymes.

Question 37. What are the different types of transpiration? Or, Classify transpiration based on its site of occurrence.
Answer: Based on the type of plant organs through which water is lost, there are three kinds of transpiration, viz. cuticular, lenticular, and stomatal.

I. Cuticular Transpiration
The physiological process of loss of water in the form of water vapor through the cuticle of the exposed surface of plant organs is known as cuticular transpiration.

The cuticle is a waxy layer on the leaf covering the epidermis and preventing transpiration. However, there are some scattered pores present in the cuticle which results in
the loss of water all through during the day and night.

II. Lenticular Transpiration
The physiological process of water loss in the form of water vapor through the lenticels of woody stems and fruit walls is termed lenticular transpiration.

Structure of lenticel :
Lenticels are minute lens-shaped pores present in the secondary epidermis (periderm) of woody stem and fruit walls. They are constituted of a loose mass of complementary cells and intermediate air spaces. The minute opening of the lenticel always remains open because of the absence of guard cells.

 

III. Stomatal Transpiration
The process of loss of water in the form of water vapor through the openings of stomata is termed stomatal transpiration. It accounts for 80-90% of transpiration in plants.

The stomata is a simple opening, guarded by guard cells, they have a sub-stomatal chamber surrounded by subsidiary cells.

1. Distribution of stomata:
Stomata is present in the leaves, and also in the young stems, floral parts, and fruit walls of opening angiosperms except in submerged hydrophytes. It is also present in the leaves of pteridophytes and even in mosses.

Question 38. What are the beneficial and harmful effects of transpiration?
Answer:
Beneficial effects of transpiration :
[1] Ascent of sap :
By transpiration, water and minerals reach the top leaves of trees.

[2] Elimination of excess water :
By transpiration, excess water from the plant body is removed. It eases the physiological activities within the cells.

[3] Cooling plant body :
By this process, the latent heat of evaporation is lost from the plant body.

Harmful effects of transpiration :
[1] Drying of leaves and twigs :
Excess transpiration reduces water content in plant cells. As a result, leaves and softer parts of plants become dry.

[2] Wilting :
In case of excess transpiration, the cells lose turgidity and shrink. As a result, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.

So, Curtis described the transpiration process as a “necessary evil” for the plants.

Question 39. Define plant circulation. Mention the medium of circulation.
Answer:
Plant Circulation :
The process by which the movement of food, water, and minerals takes place through the special conducting tissue like the xylem and phloem is called plant circulation.

The medium of circulation in plants is water.

Question 40. Differentiate between Diffusion and Osmosis.
Answer:

Question 41. Define active transport. Write the steps of active transport.
Answer:
Active Transport :
Active transport is the passage of a substance from its lower to higher concentration, using energy from the cell, through a living cell membrane. The transport of matter in the form of ions or molecules across the cell membrane utilizing metabolic energy is called active transport.

The process of active transport through carriers has the following steps —

It takes place against a concentration gradient, i.e., from lower to higher concentration. On the outer surface of the cell membrane substrate binds to the membrane protein carrier. The
carrier—substrate complex thus formed moves across the cell membrane. Reaching the inner surface of the cell membrane, the carrier substrate complex breaks. The molecules or ions are released and enter cells. The carrier returns to its original state and is free to accept other ions or molecules.

Question 42. Define the Ascent of Sap. Describe the factors affecting the ascent of sap.
Answer:
Ascent of Sap :
The transport of water and minerals from root to leaves through the xylem vessel, against the force of gravity is called the ascent of sap.

Factors:
(1) Root pressure :
The pressure develops in the roots due to the inflow of water, which helps in pushing the plant sap upward.

Root pressure is built up due to cell-to-cell osmosis in the root tissue. As one turgid cell presses the next cell, the force of the flow of water increases inward. When water
reaches the xylem vessels, it enters the pores of their thick walls with considerable force. Thus the root pressure is one of the forces to raise water through the stem into the leaves.

(2) Adhesion — Cohesion theory :
Water molecules remain attached by cohesive force and tend to adhere to the inner wall of the xylem vessel by adhesive force. The combined effect of these forces develops the continuation of water molecules in the xylem vessel, which extends from the roots to the stomata of leaves.

(3) Transpiration pull :
As the water is lost from the leaf surface by transpiration, more water molecules are pulled up due to the tendency of water molecules to remain joined and thus produce a continuous column of water through the stem.

Question 43. Write the concept of cell-to-cell transport.
Answer: The process of transfer of water and other substances from one cell to another cell is called cell-to-cell transportation. It takes place by diffusion, osmosis, or active
transport methods.

Gases like O₂ and CO₂  move from one cell to another by diffusion process. Water passes by the osmosis process. Sugar is transported from the leaf to other parts by phloem tissue by
the active transport methods.

Question 44. Define translocation. Explain the mechanism of transportation of food in plants.
Answer:
Translocation :
The process of movement of water-soluble sugar from the leaves to other parts of the plant through phloem tissue is called translocation.

Mechanism :
Munch Mass Flow Hypothesis — According to Munch, leaves act as a source of food and have a higher concentration of food. From the leaves, it easily reaches the region of lower concentration with the help of diffusion pressure.

Various steps of translocation are —
(1) leaves as the supplying cells and the root as the receiving cells of any plant. The connecting link between leaves and roots can be represented by xylem and phloem tissue.
(2) Carbohydrates are continuously synthesized in mesophyll cells of leaves. The suction pressure of these cells increases, due to which water from adjoining cells is absorbed. This allows the movement of dissolved food into a sieve tube.
(3) Since the food is actively transported, it requires energy in the form of ATP. During active transport, a sieve tube of phloem tissue is located at the source (leaf) and unloaded at the sink (root) or consumption end.

Question 45. What are the types of Osmosis? What are the types of membranes?
Answer:
Types of Osmosis :
About any living cell, osmosis may be of two types—
(1) Endosmosis — The process by which the solvent molecules from outside enter into the cell, is known as endosmosis.
(2) Exosmosis — The reverse process of endosmosis which involves the exit of solvent molecules from the cell, is known as exosmosis.

Nature of membranes :
According to physical properties, the membranes are of three types.
(1) Permeable membrane—Such membrane allows all the molecules
or ions of a solution (both solute and solvent molecules) to pass through it, e.g., filter paper cell wall, etc.
(2) Semi-permeable membrane — Such membrane allows passage of water (solvent) molecules and positively charged hydrogen ions, but not the solute molecules nor the other positively charged and negatively charged particles, e.g., parchment
paper, air bladder of fish, egg’s membrane, etc. The semi-permeable membrane can be better termed as differentially permeable, which allows passage of some solutes, but holds back others at different rates of diffusion.
(3) Impermeable membrane — It does not allow either the solute or the solvent molecules to pass, e.g. rubber sheet, or plastic sheet.

A membrane that permits certain substances to pass through more easily than the other is said to be selectively permeable.

Question 46. Distinguish between upward circulation and downward circulation.
Answer:
Difference between Upward circulation and Downward circulation :

 

Question 47. Explain the movement of gases in plants.
Answer: Photosynthesis in plants involves the intake of carbon dioxide and disposal of oxygen. During respiration plants use oxygen and give out carbon dioxide. In plants, there is no respiratorganizeriser: The elaborate liquid transport system cannot be used in the transport of gases. The leaves are well adapted to carry out gaseous exchange during photosynthesis. The rate of respiration in roots, stems, and leaves of plants is lower than that of animals. In the leaf and stem of plants the living cells are located close to the surface. The loosely arranged parenchyma cells with intercellular spaces in leaves, stems and roots provide an interconnecting system of air spaces. The diffusion of gases is faster through the air than through water. So diffusion of oxygen and carbon dioxide takes place rapidly through the interconnecting system of intercellular air spaces. These gases also pass through the cell wall and plasma membrane by a diffusion process. Aquaporin channels in the plasma membrane help in diffusion across the membrane.

[1] Absorption of gases by leaves :
Gaseous exchange in leaves takes’ place through stomata when light falls on a leaf. These openings remain open in the morning and close during the night. This happens due to a change in the turgor of the guard cells. Guard cells possess a thick and elastic inner wall. When turgor develops the outer thin wall of the guard cell extends out forcing the inner walls into a crescent shape, resulting in the opening of the stomata.

Again, loss of turgor causes inner walls to regain their original shape resulting in the closing of stomata. During the day when osmotic pressure in the lower epidermal cells remains constant and the osmotic pressure of guard cells increases then the stomata open. In the evening stomata closes when the osmotic pressure of guard cells drops to nearly that of surrounding cells.

[2] Absorption of gases by Roots and Stems :
The dead cork cells present in mature roots and woody stems contain a waterproof substathathich makes the cork impervious to oxygen, carbon dioxide, and water.

Question 48. Explain the mechanism of cell-to-cell transport.
Answer: The process of transfer of water & other substances from one cell to its neighboring cells, is known as cell-to-cell transport. This occurs either by diffusion or osmosis or by active transport.
[1] Diffusible materials like O₂, CO_2, etc. move from one cell to the next by diffusion.
[2] Water passes from one cell to another by cell-to-cell osmosis.
[3] Sugar is loaded into the phloem cells from the leaf cells by water-rich cells with means of active transport. Through this process, the food cell’s less water material is transported to all parts of the plant’s body.

 

Question 49. What are the different steps in the ascent of sap?
Answer:
Steps in ascent of sap :
Transpiration is the process that acts as a driving force for the ascent of sap, from roots to the top of a tall tree via xylem elements. The sequence of events during the ascent of sap occurs in the following order.
[1] Evaporation of water through stomata, _”aspiration pull
[2] Lowering of turgor pressure of leaf cells.
[3] The cells uptake water from the xylem elements.

[4] The aylenivesel cohesive and adhesive forces of water molecules maintain the water column within the xylem vessels.
[5] Roots absorb water and minerals from the soil water cell to cell} spongy cells by transpiration imbibition and endosmosis, which Saran moves through the endodermis and reaches the xylem vessels. scent of sap

Question 49. Explain the process of transportation of food in plants.
Answer:
Transportation of food in plants :
Transportation of food in plants occurs through a sieve tube of phloem. Regarding the mechanism of this process, the pressure flow hypothesis by Ernst Munch is the most accepted one. According to this hypothesis, the following events occur during food transport in plants.

Transfer of food from mesophyll tissue to sieve tube :
In water and food mesophyll tissues, glucose produced by photosynthesis is soon converted into a larger sugar (sucrose). The sucrose solution is then transferred into the sieve tube via bundle sheath cells, phloem parenchyma, and companion cells by cell-to-cell transport.

Creation of pressure within the sieve tube :
With the entry of sucrose, the cytoplasm of the sieve tube becomes more dense. As a result, a concentration gradient develops between the sieve tube & neighboring xylem vessels. Due to this, water moves into the sieve tube from xylem vessels by osmosis, thereby, creating oc ’ additional pressure within the sieve tubes.

The flow of food :
This mounting pressure produced within the sieve tubes pushes the food solution down to different parts of the way only
the plant body. Finally, the sucrose solution enters into the tissue cells from the sieve tube. fiber According to another concept, some fin contractile protein fibril vessels
extend along the sieve tubes through the sieves. These fibrils contract and expand continuously to drive the food solution through a sieve tube.

Question 50. Mention the role of osmosis in plant circulation.
Answer:
Role of osmosis —
(1) Osmosis helps in the entry of water molecules from the soil into the root hair.
(2) The water molecules from the root hair cross the cortex of the root and come to the endodermis by the process called cell-to-cell osmosis.
(3) Osmosis is essential for making the cells turgid. Such turgidity is necessary for the enlargement of meristematic cells, growth of organ rigidity, and flaccidity of guard cells necessary for opening and closing of stomata.
(4) Osmosis in plants directly controls the dehiscence of other lobes, fruits, etc.
(5) Small weak herbs can stand erect due to an increase in turgidity of the cells in the stem by endosmosis.
(6) In unicellular organisms and simple multicellular ones, osmosis plays the most important role in the entry of water from the surroundings and the maintenance of water balance. (6) In higher animals, continuous exchange of water through osmosis takes place amongst blood, tissue fluid, tissue cells, and lymph in the capillary bed and this is very important in regulating the water balance in higher animals.
(7) Various plant movements are largely due to osmotic phenomena.

Question 51. Define transpiration. Mention the sites of transpiration.
Answer:
Transpiration :
The loss of water as water vapor from the aerial parts of the plant is called transpiration.

Transpiration is a very useful process for the plants for two reasons :
one, to get rid of the excess water absorbed, and two, for cooling the plant in hot weather.

Transpiration takes place in plants from three different regions :
(1) From the leaves through the stomata (Stomatal transpiration)
(2) Directly from the surface of the leaf and stem (Cuticular transpiration)
(3) From the lenticels which are the minute openings on the surface of the old stem (Lenticular transpiration).

Question 52. Name the factors controlling transpiration.
Answer:
(1) Temperature :
An increase in temperature allows more water to evaporate and a decrease in temperature reduces evaporation.

(2) Humidity :
Transpiration is reduced if the air outside is humid. High humidity in the air reduces the rate of outward diffusion of the internal water vapor across stomata, thereby reducing the rate of transpiration.

(3) Air movement (Velocity of wind) :
Transpiration increases with the velocity of the wind. If the wind blows faster, the water vapor released during transpiration is removed faster.

(4) Light :
During the day, the stomata are open to facilitate the. inward diffusion of CO, for photosynthesis. During the night they are closed. Therefore, more transpiration occurs during the day.

(5) Structure of leaf :
Narrow leaves, fewer stomata, rolled or folded leaves, and covering of leaves through the cuticle and sunken stomata reduce the loss of water in the transpiration process.

Question 53. Mention the significance of transpiration.
Answer:
(1) Elimination of excess water from the plant body.
(2) Evaporation reduces the temperature of the leaf surface and causes a cooling effect in hot summer days.
(3) Transpiration helps in the ascent of sap by producing a suction force acting from the top of a plant.
(4) It helps in the distribution of water and mineral salts throughout the plant body. The higher the rate of transpiration, the greater the rate of absorption of water and solute from the soil.

Question 54. Write three differences between Evaporation and Transpiration.
Answer:

Question 55. Define antitranspirant, guttation, and bleeding.
Answer: Antitranspirants are physical or chemical agents that help in reducing excessive loss of water by keeping stomatal pores closed, eg.-plastic film, wax emulsion, aspirin, and dimethyl silicon.

Guttation :
Loss of water in the form of water droplets along the margin of the leaf in the morning is called guttation. It takes place through the Aydathodes.

Bleeding :
The plant sap bleeds from the ruptured or cut surfaces of the plant. The root pressure generated by a plant assists in bleeding.

Question 56. What do you mean by “Ascent of sap”? What is the relation between transpiration and the ascent of sap?
Answer:
(i) Ascent of sap:—
The upward movement of water along with dissolved mineral
elements through the xylem vessels from root to leaf is known as the ‘Ascent of Sap’.

(ii) Relation between transpiration and ascent of sap:—
Transpiration:-
The loss of water in the form of water vapor from the aerial parts of the plant’s body is called transpiration.

Ascent of sap:-
The upward movement of sap from the root xylem to leaf mesophyll tissue through the stem xylem is called ascent of sap.

Relation:-
The ascent of sap supplies the raw material to the process of transpiration and transpiration provides a chance for the happening of ascent of sap. Thus both these processes are complementary to each other. The more the transpiration, the more absorption and ascent of sap.

Question 57. What is Circulation? Discuss how water reaches into the leaves from the roots in a plant body.
Answer:
(1) Circulation:—
The transfer of nutrients, gases, excretory products, hormones, etc. from one part of the living body to another part of the living body through a liquid medium is called circulation.

(2) Method of reaching water from root to leaves in a plant body:—
The process by which water moves upwards from root to leaf is called the ascent of sap.

Many theories were put forward by various scientists from time to time but the “Cohesive adhesive force and transpiration pull theory” as proposed by Dixon and Jolly in 1894 is the most acceptable.

The cohesive force exists between two water molecules within xylem vessels. This force keeps the water column unbroken within xylem vessels.

 

The adhesive force exists between the water column and the wall of the xylem vessel. The water present within intercellular spaces of mesophyll tissue is changed in the vapor by the process of transpiration. This phenomenon creates a pull in the water column of the xylem vessel. This pull acts from the upper part to the lower part of the column. So its effect is first realized by the water present in the leaf xylem then the stem and the last at the root xylem. Thus water uplifts and continues till the process of transpiration is in action.

Question 58. What is transpiration? What are the various factors which influence transpiration?
Answer:
Transpiration:—
The process of loss of water in the form of water vapor from the internal tissue of aerial parts of plants is known as transpiration.

Factors influencing transpiration:—
There are various factors which affect the rate of transpiration.
These factors are divided into two groups:—
1. External factors:—
(1) Light:—
Light is most important for the opening and closing of stomata. In the daytime, due to the presence of light, the stomata remain open and transpiration of water takes place normally. At night the stomata remain closed and consequently, the transpiration is checked. Thus the rate of transpiration increases in light and decreases in darkness. Light also affects transpiration by increasing the temperature of the leaf surface.

(2) Temperature:—
Temperature shows a direct effect on transpiration. Due to the rise of temperature, the relative humidity of the air decreases and then there will be an increase in the rate of transpiration. If temperature is low then there will be a decrease in the rate of transpiration.

(3) Humidity of air:—
There is an increase or decrease in the rate of transpiration according to whether the air is dry or moist. If the atmosphere is dry there will be more transpiration.

(4) Wind:—
During high velocity of wind, the transpiration becomes very active because the water vapors are instantly removed and the area around the transpiring surface is not allowed to become saturated. During a slow breeze, the water vapors are not so quickly removed, which reduces the rate of transpiration.

(5) Atmospheric pressure:—
The rate of transpiration increases due to a decrease in atmospheric pressure.

(6) Soil water:—
The rate of transpiration increases due to an increase in the quantity of capillary water in the soil.

2. Internal factors:—
(1) Presence of cuticles on the leaf surface:— The rate of transpiration decreases due to the presence of a cuticle layer on the surface of the leaf.

(2) Number of stomata:—
Several stomata directly affect the rate of transpiration. If the number of stomata is less, the rate of stomata will be low.

(3) Leaf area:—
There will be more water loss from a plant having a larger leaf area than a smaller area.

(4) Leaf structure:—
The structure of the leaf controls the rate of transpiration. In
xerophytes (ex. cactus) the rate of transpiration is low due to the modification of the leaf into the spine.

(5) Hormones:—
Cytokinin controls the opening and closing of stomata. This affects the rate of transpiration.

Question 59. Describe the experiment to measure the rate of transpiration by Ganong’s photometer.
Answer:
Ganong’s photometer:—
In this apparatus, there is a horizontal capillary tube which is graduated. One end of this tube is bent downward and at the lower end of this bent tube, there is a hole inside the wall, through which an air bubble can be introduced. The other end of the horizontal tube opens into another horizontal but wider tube that is bent upward to end in a smaller bell jar for holding the plant twig. The broader horizontal tube is also connected by a vertically raised water reservoir funnel which is provided with stop-cock in the connecting tube to control the water supply.

Method:—
In the beginning, water is a Demonstration of the rate of transpiration filled in all parts of the tubes by opening by Ganong photometer the stop-cock of the water reservoir. A plant twig is fixed in a one-holed rubber stopper, the latter being fixed to the end of the broad mouth in an air-tight manner. The lower bent end of the capillary. the tube is immersed in a beaker of water. At this point, water should fill all the horizontal tubes, the vertical cup tube containing twigs, and the capillary tube, and the stop-cock of the water reservoir is now closed. An air bubble is introduced through the hole of the downward-bent tube end. As the plant loses water by transpiration, it exerts a suction force, so the bubble moves forward. The number of divisions in which the air bubble travels in a limited time gives an idea of the rate of transpiration.

Chapter 3 Physiological Processes Of Life Respiration

Question 60. What is meant by the release of energy during respiration?
Answer: The sun is the ultimate source of energy. Its solar energy is transformed into potential chemical energy by green plants during the process of photosynthesis. The potential chemical energy is stored within glucose which is a product of photosynthesis. We obtained energy from the food.

The simple forms of food like glucose, amino acids, fatty acids, etc. are oxidized within the cell. The potential chemical energy of food is transformed into kinetic energy by the process of respiration. Some part of this energy is stored within ATP molecules. Living organisms use the energy which is stored within ATP as per their requirement. Some part of chemical energy is also transformed into heat energy which is necessary for keeping our body temperature constant. A part of chemical energy is converted into light in some animals, like glow worms. In some animals, the chemical energy of food is converted into electricity.

Example — Electric ray fish.

Question 61. Glucose produced during the time in plants is stored in which form and where in the plant body? Why does that occur?
Answer:
(1) Glucose produced during the time in plants is stored in the form of assimilatory starch in leaves. During night the Glucose is stored in the form of permanent starch in the root cells.

(2) Reason:-
Glucose is produced by the process of photosynthesis during day time. It is soluble in water. Its high concentration reduces the rate of photosynthesis.

To avoid this condition, soluble glucose is converted into insoluble starch grains temporarily in mesophyll cells in the presence of the element potassium. This starch is called assimilatory starch. During the night, the assimilatory starch of mesophyll cells is converted into. soluble glucose and translocated to storage organs like root or stem through the sieve tube of phloem. Here soluble glucose is transformed into permanent insoluble starch with the help of amyloplast or leucoplast.

In many plants permanent starch is formed in storage tissue like the cortex or r pith or endodermis or in special organs like tubers and rhizomes.

Question 62. Discuss anaerobic respiration with an example.
Answer: The process of respiration which occurs in the absence of free oxygen in the cytoplasm of a cell in the presence of enzymes comparatively less amount of energy is released, called anaerobic respiration.

Example — Tapeworm, Yeast.

Question 63. Write any three differences between photosynthesis and respiration.
Answer:

Question 64. Discuss the significance of Respiration.
Answer:
Significance of Respiration:-

(1) Release of energy:-
The potential chemical energy of food is transformed into kinetic energy by which different organs of the body work. Some quantity of this energy is stored in ATP and some quantity is used to keep body temperature normal.

(2) Maintain the balance of O, and CO₂  in the environment:-
During respiration, living beings take O₂ gas and give out CO₂  gas, while during photosynthesis green plants take CO₂ gas and give out oxygen gas. So, by the combined action of respiration and photosynthesis, the balance ofO₂ and CO₂ is maintained in the environment.

Question 65. What is respiration? Write two differences between aerobic and anaerobic respiration. What is meant by “release of energy takes place in respiration”?
Answer:
(1) Respiration:—
The catabolic reaction _ which occurs continuously within all living cells oxidizes food substances and changes the potential chemical energy of food into kinetic energy
is called respiration.

Equation:-

(2) Difference between aerobic and anaerobic respiration:—

(3) “Release of energy takes place in respiration” —
Every living organism requires energy to perform various life– continuing activity. They obtain energy from the food. Food contains chemical energy which is the transformed form of radiant energy. Now the process of respiration changes this potential chemical energy into kinetic energy. in the form of ATP molecules. The conversion of potential chemical energy of
food into kinetic energy which is used by organs is the meaning of release of energy.

Question 66. Wherefrom do organisms get the oxygen necessary for their respiration? Discuss the importance of respiration in maintaining O₂— CO₂ balance in the atmosphere. Mentioning the environment of each write the names of the animals in which the gill and trachea act as respiratory organs
Answer:
(1) They get oxygen necessary for their respiration from their respective environment, i.e., aquatics from water and terrestrials from atmospheric air.

(2) Importance of respiration in maintaining O,- CO, balance in the atmosphere:-
The percentage of oxygen gas and carbon dioxide gas in the atmosphere is 20.60% and 0.03% respectively. The living organism takes in oxygen and gives out carbon dioxide during respiration, but green plant during day time takes in CO₂ and give out O₂ during photosynthesis. Thus we see that these two biological processes by their combined action maintain the balance of O₂ and CO₂ in the atmosphere.

Question 67. Mention any two differences between photosynthesis and respiration. Explain the main two ways by which the living world benefits due to respiration. Wherefrom do fully submerged plants take oxygen for respiration?
Answer:
(1) Two differences between photosynthesis and respiration:

(2) Benefit obtained by respiration:—
(1) Release of energy:—
The chemical energy of the food is transformed into kinetic energy by the process of respiration. This kinetic energy is used by organs of the body to continue life.

The heat which is produced during this process is essential to keep our body temperature normal.
(2) Maintenance of O₂—CO₂ balance in the environment:— Oxygen gas is taken in and carbon dioxide gas is given out during respiration but during photosynthesis carbon dioxide gas is taken in and oxygen gas is given out. Thus the process of respiration takes part in the balance of O₂-CO₂ in the environment.
(3) From the water.

Question 68. How do photosynthesis and respiration take place simultaneously in green plants under the sunlight? Discuss the importance of respiration in maintaining O₂
Answer:
(1) Way of occurrence of photosynthesis and respiration simultaneously in green plants under the sunlight:- Photosynthesis takes place within the chloroplast. Plants get CO₂ from air and water from the soil. Glucose, water, and oxygen gas are produced as end products. Respiration takes place within the cytoplasm and mitochondria. Glucose and oxygen are its raw materials. Plants get these materials from the cell because they are produced during photosynthesis. CO₂ and H₂O are end products of respiration. These are utilized by plants for photosynthesis.

Thus we see that by supplying raw materials for each other, these processes occur smoothly in green plants under the sunlight.

(2) Importance of respiration in maintaining O₂—-CO₂ balance in the atmosphere :—
The percentage of oxygen gas and carbon dioxide gas in the atmosphere is 20.60% and 0.03%-—0.04% respectively. The living organism takes in oxygen and gives out carbon dioxide during respiration, but green plant during day time takes in CO₂ and give out O₂ during photosynthesis. Thus we see that these two biological processes by their combined action maintain the balance of O₂ and CO₂ in the atmosphere.
(3) Name of the respiratory organ in prawn – Gills.

Question 69. What is aerobic respiration? What is the difference between breathing and respiration?
Answer:
(1) Aerobic Respiration:-
The complete oxidation of food which occurs continuously within living cells, cytoplasm, and mitochondria in the presence of free oxygen to produce carbon dioxide, water, and 686 KCal energy is called aerobic respiration.

Equation:-
(2) Difference between breathing and respiration:-

Question 70. Where does aerobic respiration take place in a cell? Name the chief respiratory organs of Amoeba, Cockroaches, Tadpole, and a bird. Through which part of plant body exchange of respiratory gases take place in case of fully merged aquatic ones?
Answer:
1. Place for aerobic respiration:—
(1) Cytoplasm,
(2) Mitochondria.

2. Name of respiratory organs:—

3. From all the parts of the plant body exchange of respiratory gases takes place in the case of fully merged aquatic ones.

Question 71. What is Respiration? How is it related to nutrition? Mention three main types of respiratory organs in animals.
Answer:
(1) Respiration:—
The catabolic reaction that occurs continuously within all
living cells to oxidize food substances and to change the potential chemical energy of food into kinetic energy is called respiration.

(ii) Relation between respiration and nutrition:—
Respiration :
The oxidative breakdown of substances in living cells to release energy is called respiration

Nutrition :
The total of processes like ingestion, digestion, absorption, assimilation, and egestion is called nutrition.

Relation:-
The process of nutrition supplies the raw materials such as glucose, amino acid and fatty acid for respiration and respiration liberates energy which is necessary for nutrition. Thus both these processes are complementary to each other.
(3) Name of three main types of respiratory organs:—

Question 72. Write three differences between anaerobic and aerobic respiration. Give two examples of fermentation.
Answer:
(1) Difference between anaerobic and aerobic respiration.

(2) Two examples of fermentation :
(1) Alcoholic fermentation.
(2) Lactic acid fermentation.

Question 73. Where and when does respiration take place in a cell of a living body? Define aerobic and anaerobic respiration.
Answer:
(1) Place – Respiration takes place within the cytoplasm and mitochondria of a living cell.
(2) Time – It takes place day and night continuously.
(3) Aerobic Respiration:—
The complete oxidation of food which occurs continuously within living cells, cytoplasm, and mitochondria in the presence of free oxygen to produce carbon dioxide, water, and 686 KCal energy is called aerobic respiration.

Equation –

(4) Anaerobic respiration:-
The incomplete oxidation of food which occurs continuously within living cells” cytoplasm in the absence of free oxygen to produce ethyl alcohol, CO_2, and energy in plant cells but lactic acid and energy in animal cells is called anaerobic respiration.

Equation –

Question 74. How does aerobic respiration differ from anaerobic respiration? Mention two practical applications of alcoholic fermentation.
Answer:
(i) Difference between aerobic and anaerobic respiration:-

(ii) Practical application of alcoholic fermentation:-
(1) It helps in the production of ethyl alcohol. This alcohol is used in the production of medicine and alcoholic beverages.
(2) It also helps in the formation of double bread.

Question 75. What type of metabolic process is respiration? Why is it essential for living organisms? Write two practical importance of fermentation. What is the respiratory organ of grasshopper?
Answer:
(1) Respiration is a catabolic type of metabolic process.
(2) Respiration is essential for living organisms because it transforms the potential chemical energy of food into kinetic energy which is used by different organs and metabolic
reactions to continue the life of living organisms.

(3) Practical application of fermentation:-
(1) It is useful for the preparation of curd and vinegar.
(2) It is used in the preparation of biscuits and double bread.
(3) It is used in the preparation of ethyl alcohol.
(4) The trachea is the respiratory organ of grasshoppers.

Question 76. How are respiration and breathing interrelated?
Answer: Respiration is a cellular continuous process. Glucose, amino acids, fatty acids, and oxygen are its raw materials. They reach cells by the process of circulation.

The taking in of oxygen and giving out CO₂ by them is breathing. This process occurs between the breathing organ and the environment of living. Oxygen gas reaches within the breathing organ through the process of breathing (Inspiration). This gas mixes with blood and reaches to cell by the process of circulation. Thus breathing supplies oxygen gas for the process of respiration. It also removes CO₂ gas which is produced during the process of respiration.

Question 77. What are respiratory organs? Discuss their characteristics.
Answer: Respiratory organs are the special type of organs that help in the process of exchange of gases, i.e., O₂ and CO₂ between the environment and the organism.

Characteristic features of respiratory organs:
(1) The respiratory membrane must be thin and permeable so that there is easy gaseous exchange.
(2) The respiratory surface must be extensive to provide a greater surface area for gaseous exchange.
(3) The respiratory organ must be always kept moist to facilitate the diffusion of gases.
(4) In higher animals, the respiratory organ is highly vascularised so that blood can transport respiratory gases—O₂ from respiratory organs to different cells of the body
and vice versa for CO₂.

Question 78. Explain the common respiratory sites in plants.
Answer:
Common respiratory sites in plants are as follows :
1. Stomata :
These are microscopic apertures in the leaf epidermis of plants, guarded by two guard cells. Stomata are generally present on the ventral surface in dicot plants and both on the dorsal and ventral surface in monocot plants. Through the opening of stomata gaseous exchange takes place.

2. Lenticels :
Lenticel is a porous tissue consisting of cells with large intercellular spaces, generally on the bark of woody stems of dicot plants. It functions as a pore that provides a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark. (Tough thick bark is otherwise impermeable to gases).

3. Pneumatophores :
These are breathing roots, found in mangrove trees and they are negatively geotropic adventitious branches of the root. In fact, in saline soil, the capillary space of the soil is almost blocked by a huge deposition of NaCl. So there is less capillary air, hence the root suffers from O, deficiency. So, some of the adventitious roots bend upward and come above the soil surface to absorb O₂ directly from the air, e.g. pneumatophores in Sundri Plant.

Question 79. Discuss the various respiratory organs of animals.
Answer:
Introduction :
Usually, respiration in different animals is performed by the definite organs called respiratory organs In lower animals, the exchange of gases takes place through the body surface, whereas in higher animals, there are complex organs like trachea, lungs, etc. The following is a brief account of the different types of respiratory organs found in different animals.

1. Body surface :
In the case of aquatic animals like Amoeba, Sponges, Paramoecium, Hydra, etc. exchange of gases between cells and their environment takes place by simple diffusion through the cell membrane (body surface).

2. Skin :
Terrestrial animals like earthworms, leeches, etc. respire partly or wholly through thin and highly blood-supplied moist skin.

3. Trachea :
Insects and varieties of arthropods have elaborate networks of air-filled tubes called tracheae which open onto the body surface through the small pores called spiracles or stigmata. The trachea branches repeatedly into tubes called tracheoles through which gaseous exchange takes place.

4. Gills :
In aquatic animals like fishes, the external respiration takes place through gills. These are specialized structures dark red, provided with thin walls and blood capillaries that favor easy diffusion of gases between dissolved O₂ in water and the circulating blood passing through them. The actual site of gaseous exchange in fish is the gill lamella of the gill filament.

 

Accessory respiratory organs :
The organs that partly accomplish respiration and are additional complementary respiratory structures are called accessory respiratory organs (other than gills). Some jewel fishes like Koi, Magur, and Singhi are provided with these organs.

Accessory respiratory organs develop in addition to the normal pharyngeal gills, to help the fish live in aquatic environments with low oxygen concentration or to breathe
oxygen directly from the air, aestivate over prolonged droughts during summer, and meet extra demand for oxygen. However, accessory respiratory organs in fishes can perform gaseous exchange so long as they remain moist. Gills are incapable of utilizing oxygen in the air, so accessory respiratory organs are useful adaptive features of some fishes. Those that possess these adaptive features are called jellyfish.

6. Lungs :
Lungs are the specialized respiratory organs of all land vertebrates, e.g. birds (pigeons), reptiles (lizards, snakes), amphibians (frogs, toads), and mammals (rats, cows). [eects The aquatic mammals (e.g. whale, dolphin) are also provided with lungs. That is why | so” some animals (Whale, Dolphin, Crocodile) | senay— AS often come above the surface of the water for |°°” S\N aerial respiration.

The lungs of amphibians reptiles and mammals are paired sac-like spongy foPe contact with other structures due to the presence of air-filled alveoli. Alveoli are provided with numerous blood vessels (capillaries) for gaseous exchange. The lungs of pigeons are more compact and are supplemented by.  thin-walled 9 air sacs for storage.of air that also helps to increase buoyancy.

Question 80. Discuss the concept of cellular respiration.
Answer: What is Cellular Respiration? Cellular respiration is the oxidative, catabolic, enzymatic breakdown of organic substances when potential energy is released in the form of kinetic energy.

C₆H₁₂O₆+6O₂ __ Enzymes , 6CO₂ + 6H₂O + energy

All organisms require energy to maintain the vital function of the body. This energy is derived from the food they take. During photosynthesis, solar energy is fixed in food as potential chemical energy. This food is used as a cellular respiratory substrate which is oxidized to release energy. In the presence of O, (aerobic respiration), there is complete oxidation of food that results in a greater amount of energy release whereas, in the absence of O₂(anaerobic respiration), there is incomplete oxidation of food that yields less energy. However, the energy released by cellular respiration is stored temporarily in ATP (Adenosine Triphosphate). This ATP (energy currency) is broken to release energy for various activities of the body.

Question 81. Explain the breathing mechanism in humans
Answer:
Breathing mechanism in humans:
The human respiratory organ is a pair of lungs, present in the chest cavity. Each lung remains covered with a double-layered membrane, called pleura. The space in between these two layers is called intrapleural space, which remains filled with pleural fluid.

The organ-level respiration or breathing in man involves two phases —
(1) Inspiration and
(2) Expiration. The mechanism of breathing is discussed below.

Inspiration :
Following events occur during inspiration.
(1) Diaphragm muscles contract and move down towards the abdominal cavity.
(2) Intercostal (in between ribs) muscles contract to pull the ribs upward to some extent.
(3) By these two actions, the space inside the ribcage increases. This reduces the pressure inside the chest cavity and in the pleural fluid.
(4) In this situation, thoracic pressure reaches below the atmospheric pressure. As a result, oxygen-rich air from the atmosphere rushes into the body through the nostrils, nasal passage, glottis, larynx, trachea, bronchus, and bronchioles to reach the alveoli.

Gaseous exchange occurs between alveolar air and capillary blood. After this exchange, the air inside the lungs becomes rich in carbon dioxide (CO₂). Now the brain sends a signal for expiration and the events follow.

Expiration :
(1) The diaphragm expands and moves towards the chest cas
(2)Intercostal muscles relax and the ribs go downward to their normal position.
(3) Due to the above two actions the internal volume of the chest cavity is reduced. As a result, pressure increases in the pleural fluid & as well as in the lungs.
(4) The lungs contract and the air inside the lungs is pushed out along the reverse path.

Question 82. Write a short note on fermentation.
Answer:
Fermentation :
In this process, partial breakdown of respiratory substrates occurs in totally oxygen-free conditions.

Occurrence :
This is a special type of physiological process that occurs in different microorganisms. These include some bacteria (Lactococcus lactis, Acetobacter aceti, etc.) and fungi (yeast). In higher animals, this type, of respiration occurs in skeletal muscles. Among higher plants, this process mainly takes place in seeds, potato tubers, etc.

Process of oxidation :
Certain enzymes are secreted from some microorganisms, which help in this process. During fermentation, different organic substances such as ethanol, lactic acid, acetic acid, etc. are produced. The nature of these products upon the enzyme sécreted by the participating cell.

Fermentation occurs in skeletal muscles due to a short supply of oxygen during long and heavy exercise. In this case, lactic acid is produced as a by-product. This lactic acid, when deposited in muscles in larger quantities, causes pain and muscle cramps.

Production of energy :
In this process, only 2 molecules of ATP are produced from one molecule of glucose. The quantity of heat, generated by this respiration, varies in different types of fermentation reactions, which are as follows.

Overall equation :
Alcoholic fermentation by yeast : C₆H₁₂O₆ —-> C₂H₅OH (Ethanol) —–> + 2CO₂ + 50 kcal|mole.

Lactic acid fermentation by Lactobacillus: C₆H₁₂O₆ —-> 2CH₃CHOHCOOH (Lactic acid) + 116 kcal|mole.

Acetic acid fermentation by Acetobacter : C₆H₁₂O₆ —-> C₂H₅OH (Ethanol) —–> + CH₃COOH (Acetic acid) + H₂O + 116 kcal|mole.

Question 83. Explain the significance of respiration.
Answer:
Significance of respiration :
(1) Release of energy :
Respiration is a physiological process in which energy is
liberated. During photosynthesis, a part of the solar energy that falls on the leaves of green plants is stored as potential energy in the synthesized food. During respiration,
this potential energy is transformed into kinetic Serge which performs the following functions —
(1) A part of the released energy is eee and stored as ATP (adenosine triphosphate, an energy-rich compound) for future uses. Energy in this form can only be used in performing various physiological functions.
(2) The remaining part of the released energy raises the body temperature and is partly released as heat.
(3) The energy for emitting light by glowworms and some sea animals is derived from released heat.
(4) The energy for generating electric current by electric ray, a type of fish, comes through respiration.
(5) The calorie needs of human subjects are fulfilled through the oxidation of food (that the subject consumes) during respiration.

(2) Maintenance of O₂ — CO₂ balance :
Respiration helps to maintain oxygen and carbon dioxide balance in the environment. During photosynthesis, green plants utilize CO₂ and release O₂ in the atmosphere. This may bring about a fall in CO₂ content and an increase in O, content in the atmosphere. But it never happens because during respiration all living organisms (except anaerobes) take up O₂ and release CO₂, In this way, the process of respiration helps to maintain O₂ – CO₂ balance in the environment.

Question 84. Mention the economic importance of fermentation.
Answer:
Economic importance of fermentation :
(1) Alcohol is useful in the wine industry, preparation of different medicines, tonics, biochemical and medicinal research, biological experiments, cosmetics, etc.
(2) Vinegar contains acetic acid which is produced by acetic acid fermentation of Acetobacter.
(3) Curd contains lactic acid which is produced by lactic acid fermentation of lactobacillus.
(4) Lemon squash contains citric acid which is produced by the citric acid fermentation of Citrobacter.

Question 86. What is meant by assimilation? Mention the organs related to absorption and assimilation.
Answer:
(1) Assimilation :
The process of conversion of simple digested food within cells into complex organic substances like protoplasm is called assimilation.

In animals digested foods like glucose, amino acids, and fatty acids reach different cells from the small intestine through the process of blood circulation. Glucose is converted
into glycogen within liver cells. Excess fatty acids are deposited in various parts such as below the skin and around the liver etc.

Amino acids are converted into urea within liver cells by the ornithine cycle. Urea is excreted in the form of urine through the kidney.
(2) Organs related to absorption: villi of small intestine.
(3) Organs related to assimilation: cells of the body.

Question 87. What is the importance of the digestion of food? What type of digestion is found in man? Mention the roles of enzymes in the digestion of food.
Answer:
1. Importance of digestion of food :
(1) Digestion converts complex and insoluble food substances to simple soluble and absorbable food substances.
(2) Glucose, amino acids, and fatty acids which are the end products of digestion are absorbed through villi and mixed with blood.
(3) The digested food reaches cells by the process of circulation.
(4) These substances take part in the metabolic reactions of the cell.

Thus the process of digestion is essential for the continuation of life.
2. Holozoic type or extracellular digestion is found in man.

3. Roles of enzymes in the digestion of food substances:—

 

Question 88. Mention any two functions of Vitamin A’. Explain the importance of vitamins.
Answer:

Function of Vitamin A:-
(1) It keeps eye-sight healthy.
(2) It helps in proper growth.

Importance of vitamins in the human body:—
(1) Vitamins help in the regulation of metabolic reactions in the living body.
(2) Vitamin A is necessary for proper growth. It also helps in maintaining normal eye sight.
(3) Vitamin C keeps gums and teeth healthy.
(4) Vitamin D is necessary for the proper growth of bones.
(5) Vitamin E is necessary for the proper functioning of the reproductive system.”
(6). Vitamin K is necessary for the normal clotting of blood.

Question 89 Why are enzymes called biocatalysts? Sequentially mention the names, sites of secretion, substrate, and product of various enzymes that help in the digestion of starch in the human body.
Answer:
Enzymes are called biocatalysts because:-
(1) They are proteins by nature and are produced in living cells.
(2) They remain unchanged after the reaction is over.

Question 90. Which type of food material fulfills the nitrogen demand of the animal body? What is the end product of the digestion of that food? Write the nutritional importance of carbohydrate type of food.

Answer:
(1) Protein type of food fulfills the nitrogen demand of the animal body.
(2) The end product of protein digestion is amino acid.

(3) Nutritional importance of Carbohydrate:-
(1) It is the main source of energy for our body.
(2) Its other forms like glycogen are stored in muscle cells and act as the source of energy in the future.
(3) It is required to prevent ketosis.
(4) It helps in the development of the brain indirectly by taking part in the formation of galactolipid which is essential for the development of the brain.

Question 91. What is chyme? Explain the action of pancreatic amylase and trypsin.
Answer:
(1) Chyme :
partially digested acidic food present in the stomach is called chyme.

(2) Action of pancreatic amylase:—
It acts in an alkaline medium on starch in Duodenum and converts it into maltose.

Starch + amylase = Maltose.

(3) Action of pancreatic trypsin:—
In Duodenum it acts upon peptone and converts it into peptides.

Question 92. Write about the chemical composition of proteins. Name any two proteolytic enzymes found in the alimentary system of man. What is
roughage?
Answer:
(1) Chemical composition of protein:—
Protein molecules are large. They are formed from the combination of simple nitrogenous substances, and amino acids. Amino acids are made up of C, H, O, N, P, and S.

(2) Name of proteolytic enzyme:—
(1) Trypsin.
(2) Pepsin.

(3) Roughage:—
Non-digestible constituents of our diet which are used to prevent constipation, are called roughage.

Question 93. What is the importance of the digestion of food? What is an enzyme?
Answer:
1. Importance of digestion of food:—
(1) It converts complex and insoluble forms of food into simple, soluble, and absorbable forms of food.
(2) This process is indirectly necessary for absorption.
(3) This process prepares the raw materials for respiration.
(4) It is a basic process that helps the organism to survive.

(2) Enzyme:—
The organic compounds that are produced by living cells but without taking part in biochemical reactions within or outside a cell change the rate of chemical reaction, are called enzymes.

Question 94. Write any two general characteristics of enzymes. Mention the names of the main three types of enzymes and indicate their roles in the digestion of food substances.
Answer:
1. Two general characteristics of enzymes:-
(1) All enzymes are chemically protein in nature.
(2) Their action depends on the nature of the medium of food substances, i.e., acidic, basic, or neutral.

2. Name of main three types of enzymes –
(1) Amylolytic enzymes,
(2) proteolytic enzymes,
(3) lipolytic enzymes.

Question 95. Mention one source (from plants) for each type of food and discuss the importance of those three types of food in nutrition. Mention the importance of iodine in the food of man.
Answer:
(1) Name of three types of body-building food in man :
carbohydrate, protein, and fat.

(2) Importance of Iodine:—
It helps in the formation of ‘thyroxine’ hormone. This hormone controls different types of metabolic reactions.

Question 96. What is the importance of nutrition? Explain autotrophic and heterotrophic nutrition in plants with one example of each type.
Answer:
1. Importance of nutrition:—
(1) This process supplies nutrients to the cell. Nutrients are the raw materials for the formation of protoplasm.
(2) It helps to provide new materials to repairer replace the protoplasm in damaged tissue.
(3) It helps for protection against diseases through the assimilation of vitamins and minerals.

2. Autotrophic nutrition:—
The type of nutrition performed by the organism that prepares its food either by the process of photosynthesis or chemosynthesis is called autotrophic nutrition.

Ex – Green mango tree.

(3) Heterotrophic nutrition:—
The type of nutrition performed by all nongreen plants and all animals is called heterotrophic nutrition.

Ex – Mucor.

Question 97. Write with examples the definitions of Autotrophic and Heterotrophic nutrition in plants. Discuss briefly the first three phases of animal nutrition
mentioning the related organs.
Answer:
(1) Autotrophic nutrition:—
The type of nutrition performed by the organism that prepares its food either by the process of photosynthesis or chemosynthesis is called autotrophic nutrition.

Example of Autotrophic Nutrition:—
Nutrition in green neem plants, nutrition in sulfur bacteria.

(2) Heterotrophic nutrition:—
The type of nutrition performed by all non-green plants and all animals is called heterotrophic nutrition.

The organism in which such a type of nutrition is found is called a heterotroph. There are five types of heterotrophs:—
(1) parasite,
(2) saprophyte,
(3) insectivorous,
(4) symbiont and
(5) epiphyte.

Example of Heterotrophic Nutrition:—
Cuscuta, yeast, nepenthes, rhizobium, orchid.

(3) Name of first three phases of animal nutrition:—
(1) Ingestion,
(2) digestion,
(3) absorption.

(1) Ingestion:—
After the selection of food taking its proper quantity into the mouth cavity through the mouth is called ingestion.

Organ related to this phase —
Hand in case of man.

(2) Digestion:—
The conversion of a complex and insoluble form of food with the help of digestive enzymes into a simple or soluble form of food is called digestion.

Organs related to this phase —
Different parts of the alimentary canal such as the mouth cavity, stomach, and small intestine.

(3) Absorption:—
The transfer of simple food substances such as glucose, amino acid,  and fatty acid from the last part of the small intestine to the blood of veins through villi is called absorption.

Organ related to this phase —
Villi of the internal wall of the last part of the small intestine.

Question 98. What are the end products of digestion of carbohydrates, proteins, and fats in the case of man? Name the sources of each carbohydrate, protein,  and fat considering one from plants and one from animals.
Answer:
(1) Sources:—

(2) End products of digestion:— 

Question 99. What is Enzyme? Mention the names of three major types of food-digesting enzymes. From which parts of the digestive system protein protein-digesting enzymes are secreted?

Answer:
1. Enzyme —
The organic compounds are produced by living cells. but without taking part in bio-chemical reactions within or outside a cell change the rate of chemical reaction, are called enzymes.

2. Name of three major types of food-digesting enzymes —
(1) Amylolytic enzymes,
(2) proteolytic enzymes,
(3) lipolytic enzymes.

3. Name of parts of the digestive system:—
Stomach, Pancreas, and small intestine.

Question 100. What is meant by essential macro elements? Mention the sources of C, H,0, S, P, and K for plants.
Answer:
(1) Essential macro elements:—
The elements which in large quantities are required by living organisms for performing their different types of functions in their body are called essential macro elements. Example:- Carbon, Hydrogen, Oxygen, etc.

Question 101. What is food? What are the major types of food? What are these? What are their sources?
Answer:
(1) Food:—
The nutrients which supply energy and help in the formation of body substances are called food.

(2) Major types of food:—
The nutrients that supply energy and whose large quantities constitute our diet are called major types of food.

(3) Name of major types of food:—
Carbohydrate, protein, fat.

(4) Sources:

Question 102. Explain with the help of examples the differences between the process of nutrition in plants and animals. Mention the importance of the alimentary system in animals and indicate the place where fat is digested.
Answer:
(1) Difference between plant nutrition and animal nutrition:—

(2) Importance of the alimentary system in animals:—
(1) It helps to store food for a long time.
(2) It produces different types of enzymes from its different parts.
(3) It is the site for proper digestion.
(4) Its some part helps in the absorption of digested food.
(5) The remaining foods after absorption are stored in their last part from where it is ingested.

(3) Place of fat digestion:—
Fat is digested in the stomach and small intestine of the alimentary system.

Question 103. (1) What defects might an infant of 5-6 months develop if it fails to procure sufficient calcium from its mother’s milk to find supplementary food?
Answer:
1. The defects that develop in 5-6 month infants are as follows:-
(1) Retarted bone growth and reduced mineralization of teeth.
(2) Stunded growth will occur.
(3) He will be physically and mentally weak.
(4) He will suffer from Ricket disease.

2. Which types of food must be supplied to a normal healthy adult male in his daily diet, and each in what amount?
Answer:
Type of food Quantity of food
1. Carbohydrate 416 gm.
2. Protein 100 gm.
3. Lipid 100 gm.

3. Write a characteristic feature of each of anabolism and catabolism such that they may be termed processes of opposite nature.
Answer: In anabolism,  energy is entrapped, while during respiration energy is released.

Question 104. Define five steps of animal nutrition and mention the organs involved in each step.
Answer:
Five steps of animal nutrition:-
(1) Ingestion:—
The method of capture and intake of food is called ingestion.

Related organ — Man hand.

(2) Digestion:—
The process using which complex food substances are broken down into simpler absorbable forms is called digestion.

Related organs — Mouth and mouth cavity, stomach, small intestine.

(3) Absorption:—
The process using which the digested simpler food materials enter into the cell or blood vessels or lymph from the intestine is called absorption.

Related organs — Villi of small intestine.

(4) Assimilation:—
The process by which the absorbed food substances enter into the Protoplasm and become part of the protoplasm of a cell is called assimilation.

Related Organs — Cells.

(5) Egestion:-
The process by which the undigested food substances are eliminated from the body is called egestion.

Related Organs — Anus.

Question 106. What is a nutrient  What is the importance of nutrition?
Answer:
Nutrient :
The organic and inorganic materials that the living organism collects from nature to perform all the fundamental activities of the body are called nutrients,

e.g. Protein, fat, carbohydrates, vitamins, minerals,  and water.

Significance / Importance of nutrition :
(1) Growth promotion, repairing wear and tear of the damaged tissues,  and gaining energy to control the different metabolic processes are the main functions of nutrition.
(2) Through nutrition the potential energy stored within food is transformed into usable energy. The different physiological functions of the living body like movement, locomotion, excretion, reproduction, etc. are controlled by utilizing this energy.
(3) Nutrition helps to develop the disease-resistant power of the living body.
(4) Nutrition helps to store food in the body for future use. From that stored food (in the plant body mainly as starch and in animals as glycogen and fat) the future energy is produced during shortage of food.
(5) Nutrition plays a special role in the production of heat energy in the organisms to meet the caloric demand.

Question 107. What is Parasitic Nutrition? Classify it with examples.
Answer:
Parasitic Nutrition :
The process by which the plants obtain their necessary nutrition from any other living plants or animals of different species (host) is called parasitic nutrition. Plants drawing in nourishment are called parasites and from which nutrients are drawn in are called hosts. Parasites generally suck in the nutrients by the haustoria of their adventitious roots.
(1) Total Parasite or Holoparasite —
Plants that draw their total nourishment from their respective hosts.

Examples :
Total stem parasite — e.g. Cuscuta reflexa (dodder, swarnalata).
Total root parasite — e.g. Balanophora dioica, Rafflesia Arnoldi.

(2) Partial parasite or Semi-parasite —
Plants can prepare food as they contain chlorophyll but are dependent on the host plants for water and minerals.

Examples —
Partial stem parasite — e.g, Viscum album, Loranthus longiflorus.
Partial root parasite — e.g. Santalum album (B. Chandan).

Question 107. What is Saprophytic Nutrition? Classify it with examples.
Answer: Saprophytic Nutrition — The nutrition of certain non-green plants that draw their nourishment from the dead and decomposed organic substances formed as a result of the decay of plants and animals is termed saprophytic nutrition.
(1) Total saprophytes— Saprophytes dependent fully on dead decaying organic substances for their nutrition are called total saprophytes.

Examples :
total saprophyte — Mucor, Penicillium, Agaricus, Monotropa uniflora (devoid of roots and chlorophylls).

(2) Partial saprophytes — Green plants that depend partially on dead decaying organic matter for nutrition are called partial saprophytes.

Examples :
Partial saprophyte — Pinus (they absorb organic substances with the help of certain fungus (mycorrhiza) growing on their roots).

Question 108. Discuss Symbiontic Nutrition in animals with examples.
Answer:
Symbiotic nutrition (Mutualism ) :
When two different species of organisms live together enjoying the mutual benefit of nutrition it is called symbiotic nutrition and each species is called a symbiont.

Examples:
The symbiosis between animal and Plant :
Green Hydra and Zoochlorella (algae) live together where green hydra provides protection and shelter to zooxchlorella. In turn, Zoochlorella performs photosynthesis and provides O, to Hydra.

The symbiosis between animals and protozoa :
Termites feed on wood but they do not contain cellulase enzyme. In the digestive system of termites, there are a large number of flagellate protozoa named Trichonympha that can produce the enzyme cellulase which helps in the digestion of cellulose. Thus termites provide shelter to protozoa and protozoa provide cellulose to termites— so both of them mutually benefit

The symbiosis between Ruminant mammals and bacteria :
Ruminant mammal also needs cellulase enzyme for the digestion of cellulose which is produced by symbiotic Rumenococcus bacteria and get food and shelter, in turn, from cattle.

Question 109. Write a short note on the glands of the digestive system.
Answer:
Certain glands such as salivary glands, liver, and pancreas form the accessory organizer:
1. Salivary glands — Three pairs of salivary glands are present in the mouth cavity.
(1) Parotid gland — It is located at the corner of the mandible and ear-lobe on each side of the face.
(2) Submaxillary or Submandibular gland — It is situated in front of the sternomastoid muscle on each side and is surrounded by. the mandible:
(3) Sublingual gland — It is situated beneath the mucous membrane of the floor of the mouth and below the tongue. Salivary ducts, carrying the saliva, open into the mouth near the ‘molar teeth and also on the floor of the mouth.

Function — Salivary glands secrete saliva.

2. Liver — The liver is the largest gland of the body. It is situated below the diaphragm and above and on the right side of the stomach. It is divided mainly into the right and
left lobes. The gall bladder is an elongated, pear-shaped, muscular elastic sac about 7-8 cm long, lying under the lower surface of the liver. Bile secreted by the liver comes
out. through the hepatic and cystic and remains stored in the gall bladder. From the gall bladder, bile passes through the common bile duct into the duodenum.

Functions —
(1) Liver secretes bile.
(2) It acts as an important metabolic as well as excretory organ of the body.

3. Pancreas — Pancreas is a mixed gland that is about 20 cm long and 4 cm broad situated beneath the stomach, within the ‘C’- shaped speed of duodenum.

Functions —
(1) It is composed of pancreatic alveoli which secrete pancreatic juice (digestive juice).
(2) The cells of @ and cells of islets of Langerhans tissue of the pancreas secrete two hormones in the blood, insulin and glucagon.

Question 110. What are the functions of the alimentary system 
Answer:
Functions of the Alimentary System:
The main functions of the alimentary system are —
(1) Ingestion — Food is taken by the mouth cavity.
(2) Digestion — The complex food is converted to simple food by the process of digestion in the stomach and small intestine. Different digestive glands take part in this
process.
(3) Absorption — The digested simple food is absorbed by the villi of the small intestine of the alimentary canal.
(4) Egestion — Temporarily stored undigested food in the rectum is eliminated as stool.

Question 111. Discuss the process of digestion.
Answer:
1. Mechanical (Physical) events during digestion :
(1) Chewing (Mastication) :
It is the physical process by which solid food breaks into small fragments by teeth. These smaller fragments of food mixed with saliva form bolus that are easily swallowed. The total surface area of fragmented food particles is increased so that digestive enzymes can act better.

(2) Swallowing (Deglutition) :
The physical process (movement) by which food bolus passes from the mouth cavity into the stomach through the esophagus is called swallowing or deglutition. It is a complex inborn reflex process.

(3) Peristalsis :
It is the slow but lateral wavy movement of the alimentary canal consisting of waves of alternate contraction and relaxation by which food materials move downward in the alimentary canal. Peristalsis helps in digestion by proper mixing of food with digestive juice. It also helps in the absorption of digested food and the digestion of faces.

2. Biochemical (Enzymatic) events during digestion :
Protein, fat, carbohydrate and other macromolecules must be properly digested into soluble micromolecules so that they can be properly absorbed. During this digestion, there are profound chemical changes. Various digestive enzymes are responsible for biochemical reactions at different parts of the alimentary canal.
(1) Hydrolysis :
It means the breakdown of chemical bonds of macromolecules of food by the addition of water during enzymatic digestion.

Example : Sucrose + H₂O __Sucrase _> glucose + fructose
(C₁₂H₂₂O₁₁                             (C₆H₁₂O₆) (C₆H₁₂O₆)

Question 112. Write a short note on digestive enzymes.
Answer:
Digestive Enzymes :
Enzymes take part in digestive enzymes. They are of three types —
(1) Proteolytic enzymes or Protein — hydrolyzing enzymes — These enzymes hydrolyze proteins into polypeptides and amino acids, e.g. — Pepsin, Trypsin, Chymotrypsin, Erepsin, Renin.
(2) Lipolytic enzymes or Lipid hydrolyzing enzymes — These enzymes hydrolyze lipids (fats) into fatty acid and glycerol, e.g. Lipase (Gastric Lipase, Pancreatic Lipase,
Intestinal lipase).
(3) Amylolytic enzymes or Carbohydrate hydrolyzing enzymes — These enzymes hydrolyze the carbohydrate into needed items (glucose), e.g. — Amylase, Sucrase, Lactase, Maltase, etc.

Question 113. Write a short note on metabolism.
Answer:
Definition :
Metabolism is the total of biochemical reactions in the living cell of an organism, which involves the synthesis of complex substances from simple ones with the utilization of energy, and the breakdown of complex substances into simpler ones with the release of energy.

The process of metabolism is completed in two steps — anabolism and catabolism.

Anabolism :
It is the constructive process by which complex molecules are formed from simpler units with the help of energy increasing the dry weight of the organism.

Example: Formation of glycogen from glucose; formation of protein from amino acids, etc.

Catabolism :
It is the destructive process by which complex molecules are broken into simpler units with the liberation of energy resulting in a decrease in the dry weight of the organism.

Example: By respiration, glucose is broken into CO₂ and H₂O with the release of energy.

Anabolism and catabolism are opposite processes of reversible chemical reactions which may be represented as follows :
anabolism
Small molecules <——-> Large molecules
catabolism

Question 114. State the significance of metabolism. Define a balanced diet.
Answer:
Significance of metabolism:
1. The functional activities of the body depend on various metabolic reactions continuously taking place within the cells of an organism.
2. Various anabolic reactions result in the formation of macromolecules like fat, glycogen, etc. that are stored in respective organs, e.g. fat in adipose tissue, glycogen in liver and muscle, etc.
3. Many enzymes participate in all metabolic reactions resulting in intramolecular or intermolecular transformation.

Question 115. Calculate the daily energy requirement for an adult human.
Answer:
Calculation of energy required daily for an adult human :
Calorie (cal) is the unit of energy and is defined as the amount of heat energy which can raise kilocalorie (Kcal).

For daily calorie requirements of an adult healthy man, weighing about 60 — 70 kg and doing moderate work is about 2500 — 3000 Kcal. This amount of energy is derived from energy-yielding food like carbohydrates, proteins, and fats. On complete oxidation (combustion) these types of food yield the following amount of energy :

1 gram of carbohydrate ——>yields —4.0Kcal
1 gram of protein        ——-> Yields — 4.1 Kcal
1 gram of fat                ——-> Yields — 9.3 Kcal

Therefore, a man (60 — 70 kg body weight) doing moderate work requires about 3000 Calories. Thus to fulfill this calorie requirement he should consume the following amount of carbohydrates, proteins, and fats in the ratio of approximately 4: 1: 1, (Carbohydrate: Protein: Fat) along with vitamins, minerals, and water to satisfy his or her daily calorie (energy) requirements.

Carbohydrates      415 gram =415 x 4.0 = 1660 Kcal
Proteins 100 gram 100 gram =100×4.1  = 410 Kcal
Fats 100 gram       100 gram =100 x 9.3 = 930 Kcal
—————————————————-
                           Total energy yields      = 3000 Kcal

Question 116. Describe the different types of plant nutrition.
Answer:
Nutrition in plants :
Plants and animals do not obtain food by the same processes. Plants and some bacteria have the green pigment chlorophyll to help synthesize food, while animals, fungi, and other bacteria depend on other organisms for food.

Based on this, there are two main modes of nutrition: autotrophic and heterotrophic.

1. Autotrophic nutrition :
The term ‘autotroph’ is derived from two Greek words autos (self) and trophe (nutrition). In autotrophic nutrition, an organism makes its food from simple raw materials.

2. Heterotrophic nutrition :
Unlike autotrophs, which manufacture their food, heterotrophic organisms obtain food from other organisms. All animals and non-green plants come under this category.

Depending upon the mode of living and the mode of intake of food, heterotrophs may be parasitic, saprophytic, symbiotic, and insectivorous.

(1) Parasitic :
Parasites, obtain their nutrition from hosts. These parasites maintain physical contact with the host plant through haustoria (parasitic roots). These haustoria penetrate host tissue make connections with the conducting elements of the host and draw nourishment.

Example :
Total stem parasites like Cuscuta and root parasites like Orobanche are never green and consequently, they have no power to prepare their food. They get all their food supply from the host plants.

(2) Saprophytic :
Saprophytes get their nutrition from dead and decaying organic matter.

Example :
Neottia (Bird’s nest plant) and Monotropa (Indian pipe) are flowering plants whose roots constitute a mycorrhizal association with fungal hyphae, which helps in absorption.

(3) Symbiotic :
Symbiosis is the habitual living together of organisms of different species. The term is usually restricted to a dependent relationship that is beneficial to both participants (also called mutualism). Symbiotic relationships in plants include the interdependence of the algae and the fungus that form a lichen and the relationship between leguminous plants and the nitrogen-fixing bacteria, which is important in agriculture (nitrogen cycle).

(4) Insectivorous :
They are said to be partly autotrophic and partly heterotrophic. These autotrophs supplement their nutritional requirements by trapping and digesting insects and other small animals. The trapped insects are killed and their proteins are digested by proteolytic enzymes secreted by the epidermis of the leaf.

Question 117. Describe the different types of animal nutrition.
Answer:
Nutrition in animals :
Animals are generally heterotrophic and perform holozoic nutrition. Holozoic nutrition involves the ingestion of complex organic substances. The food of most animals contains large organic substances. In this mode, small or large particles of food are consumed through an opening called mouth (ingestion). Then these are hydrolyzed into simpler and soluble forms (digestion). Simplified products are absorbed into the body and the undigested product is removed from the body and the undigested product is removed from the body (egestion).

Holozoic nutrition is broadly classified into the following categories —
1. Parasitic nutrition is a mode of heterotrophic nutrition where an organism (known as a parasite) lives on the body surface or inside the body of another type of organism (known as a host). The parasite obtains nutrition directly from the body of the host. Since these parasites derive their nourishment from their host, this interaction is often described as harmful to the host. A few examples of parasites are tapeworms, fleas, and barnacles.

2. Symbiotic nutrition :
Symbiotic nutrition is close and often long-term interaction between two or more different biological species. A symbiotic relationship is where two organisms depend on each other and are both benefited by their relationship.

Examples :
A certain kind of bacteria lives in the intestines of humans and many other animals. The human cannot digest all of the food that it eats. The bacteria eat the food that the human cannot digest and partially digest it, allowing the human to finish the job. The bacteria benefit by getting food and shelter, and the humans benefit by being able to digest the food they eat.

3. Saprozoic nutrition :
Nutrition of an animal by absorption of dissolved salts and simple organic nutrients from the surrounding medium; also refers to feeding on decaying organic matter. In this kind of nutrition, the process is started from half or fully broken down macro molecules and is a kind of extracellular digestion that is most often carried out through active transportation.

For example: spiders, house flies, etc.

4. Coprophagy :
Coprophagy is the consumption of feces. Coprophagy refers to any kind of feces eating including the eating of other species (heterospecifics), other individuals (allocoprophagy), or its own (autocoprophagy). These feces contain substantial amounts of semi-digested food.

The most notable feces-eating insect is the dung beetle and the most common is the fly. Pigs eat the feces of humans that leave a significant amount of semi-digested matter.

5. Sanguinivory :
Sanguinivory or hematophagy is the habit of certain animals feeding on blood. Sanguinivores feed on the blood of the vertebrates.

Examples :
Female mosquitoes, leeches, vampire bats, etc.

Question 118. Write a short note on human dietary needs.
Answer:
Human dietary needs :
The human diet must provide the following :
1. Calories — enough to meet our daily energy needs.
2. Amino acids — There are nine, or so, “essential” amino acids that we need for protein synthesis and that we cannot synthesize from other precursors.
3. Fatty acids — There are three “essential” fatty acids that we cannot synthesize from other precursors.
4. Minerals — Inorganic ions. We probably need 18 different ones: a few like calcium in relatively large amounts; most, like zinc, in “trace” amounts.
5. Vitamins — A dozen, or so, small organic molecules that we cannot synthesize from other precursors in our diet.

Question 119. What is the importance of a balanced diet?
Answer: A balanced diet is important because your body’s organs and tissues need proper nutrition to work effectively. Without good nutrition, your body is more prone to disease, infection, fatigue, and poor performance. Children with a poor diet run the risk of growth and developmental problems. Bad eating habits can continue for the rest of their lives.

A balanced diet is nothing but eating the right amount of food every day. How much food you need every day depends greatly on the activities you do. Other factors like age and gender also affect the amount of energy needed by every person every day. A balanced. diet provides the body with all the necessary nutrients and vitamins, thereby improving the functioning of the immune system. This not only reduces the possibility of being infected by seasonal allergies but also prevents serious health risks, like cancer, diabetes, cardiovascular diseases, etc. Such a diet also keeps you mentally by keeping your mind more alert.

Let us get introduced to the Healthy Diet Pyramid or the Food Pyramid. The Food Pyramid is widely used as a guide to eating the right amount of food every day. In the food pyramid, we can find 4 main groups of foods. A pyramid shape is used because it fits very much to illustrate the amount of food we need every day. If you take a look at the pyramid, its base is winder and as it goes higher it becomes narrower until it reaches its tip. As we go higher to the top, we eat a lesser amount of each food and as go lower, we eat more.

Question 120. Describe the different metabolism-related problems.
Answer: An abnormal diet may lead to certain metabolism-related problems, in which a person suffers from different health hazards. A few of those are mentioned below.
1. Diabetes :
In this disease, the blood sugar level goes above normal [70 — 110 mg/ dl in fasting]. It may lead to dysfunction of the kidneys, eyes heart nerves, and other organs

2. Liver cirrhosis :
This is caused by the consumption of excessive alcohol and fatty food. In this disease, liver tissue is seriously damaged, which may transform into liver cancer if not treated early.

3. High blood pressure :
Systolic and Diastolic pressure above 140 and 90 mm Hg respectively is treated as high blood pressure. This disease increases the risk of cardiac and cerebral attack, kidney dysfunction, and many other health problems.

4. Obesity :
It is a metabolism-related problem that occurs due to excess intake of calories. This disease leads to elevated blood sugar, blood pressure, and cardiovascular diseases.

5. Atherosclerosis :
This is a cardiovascular disease in which the walls of arteries become rigid and the lumen reduces. It is caused by to deposition of fat derivatives and other materials in the walls of arteries.

6. Arthritis :
This is a painful inflammatory disease, caused by due deposition of some toxic metabolic wastes within bone joints.

7. Ketosis :
Prolonged fasting leads to excessive protein breakdown and discharge of ketone through urine.

8. Goitre :
A deficiency of iodine in food leads to this disease, where the function of the thyroid gland is affected.

Question 121. What are biomolecules? What is the average composition of plant and animal cells?
Answer: Building block molecules are called biomolecules. They make up the body of organisms, cells, and cell organelles.

It is of two types —
(1) Macromolecules :
Small molecule size with low molecular weight.

eg. minerals, water, gases, carbohydrates, etc,

(2) Macromolecules :
Large molecule size with high molecular weight. It is formed by polymerization of many micromolecules of one type.

eg: Protein, Polysaccharides, Nucleic acid.

Question 122. Write the roles of inorganic compounds in the body of a living organism.
Answer:
Water :
It is the most abundant inorganic compound in living organisms. On average water forms 65-75% of protoplasm.

It acts as a solvent for all soluble substances in the cell. It provides an aqueous medium for various cellular reactions. It provides proper hydration to protoplasm. It provides turgidity to the cells in plants. Water maintains constant body temp. In plants and animals. Water acts as a source of hydrogen in photosynthesis.

Gases :
The main gases which play an important role in metabolism are O₂ and CO₂. Oxygen is needed for the aerobic breakdown of organic food and the release of energy for life. Carbon dioxide is used by photosynthetic autotrophs for the synthesis of carbohydrates.

Question 123. What are carbohydrates? Write its functions.
Answer: Organic compound containing carbon, hydrogen, and oxygen. Its general formula is Cn(H₂0)n. Based on the number of sugar units in the molecule, it is classified as –

(1) Monosaccharides :
Contain only one sugar unit known as glycoses or simple sugar. These are the reducing agents.

Eg. Glucose (C₆H₁₂O₆)

(2) Oligosaccharides :
Carbohydrates with 2-9 monosaccharides joined together.

glucose + glucose -» Maltose
glucose + fructose -» Sucrose
glucose + galactose -» Lactose

(3) Polysaccharides :
Carbohydrates with 10 or more monosaccharide units. These are macromolecules.

Eg: Starch and cellulose.

Functions :
(1) These are structural components
(2) Play an important role in metabolic functions
(3) as a potential source of energy in cells.

Question 124. What are Amino Acids and proteins? Write their functions.
Answer: Amino acids are microbiomolecules with low molecular weight. It contains C, H, and N, S.

These are essential and non-essential amino acids.

Essential amino acids are 8 in number. These are not synthesized in animal cells and obtained through diety only. eg. Valine, Leucine, Methionine, Lysine, etc.

Non-essential amino acids are 10 in number and naturally synthesized in the body.

eg. Alanine, Arginine, Aspartic acid, Serine.

Semi-essential Amino Acid :
Only 2 in number can be synthesized in animal cells but not enough. Eg. Arginine and Histidine.

Amino Acids are used in Protein Synthesis, glucose, vitamins, and hormone synthesis.

Question 125. Write the structure and functions of the protein.
Answer: These are long-chain polymers of amino acids with very high molecular weight. It contains C, H, O, N, S and P. The bond which joins two amino acid molecules is a peptide bond.

Types of protein :
(1) Simple protein :
made of only amino acids.

eg: albumin, histone.

(2) Conjugated protein :
made of amino acid + some non-protein group.

eg: Nucleoprotein, Glycoprotein.

(3) Derived protein :
These are intermediate degradation products of protein, obtained on hydrolysis of protein.

Functions of Protein:
(1) These are structural constituents of protoplasm, protoplasmic organelle, and cell membrane.
(2) Enzymes are proteins, essential for metabolism.
(3) Cytochrome pigment helps in photosynthesis and Respiration.
(4) Haemoglobin transports oxygen in the body.
(5) Actin and myosin help in muscle contraction.
(6) Fibrinogen and thrombin help in blood clotting.

Question 126. Write the structure and functions of lipids in the human body.
Answer: Lipids are oily, greasy organic compounds, insoluble in water. Lipid molecule contains C, H, and O. They have less percentage of oxygen.

These are :
(1) Simple lipids :
are esters of fatty acids with alcohol.

(2) Compound lipids :
These are fatty acids + Alcohol + Some other group.

eg. Phospholipid, Glycolipid, Steroids Carotenoids.

Functions of lipids:
(1 Release more energy than carbohydrate
(2) Constituent of cell membrane
(3) Acts as a solvent for fat-soluble vitamins
(4) Acts as insulator.

Question 127. What are Nucleotides and Nucleic Acids?
Answer:
Nucleotides :
Nucleotides are the building block unit for Nucleic acid. These are macromolecules with low molecular weight.

Nucleotide = Pentose Sugar + Nitrogenous base + Phosphate group.

Nucleic Acid :
These are long-chain polynucleotide macromolecules. These are the most important biomolecules, and control most biological processes, including heredity.

There are two types of Nucleic acid – DNA and RNA.

DNA (Deoxyribose Nucleic Acid) :
double-stranded helical structure. Two strands are antiparallel and coiled around each other. Complementary base pairs are :

Adenine is attached to thymine with a double hydrogen bond. Guanine with cytosine with a triple hydrogen bond. DNA has the unique ability of self-replication.

Functions of DNA:
(1) It is the genetic material of all organisms (except some viruses)
(2) It takes part in genetic recombination.
(3) It can replicate itself.

RNA (Ribose Nucleic Acid): Single stranded, long chain polynucleotide. Complementary base pairs are — Adenine, Guanine, cytosine, and Uracil. These are mainly. present in cell cytoplasm.

Types:
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)

Functions :
(1) Involved in protein synthesis
(2) In certain viruses acts as the genetic material.

Question 128. What are vitamins? Writes their roles in the human body.
Answer:
Vitamins :
Vitamins are complex organic chemicals that are present in our food in small quantities. Vitamins are essential for growth, good health, proper vision, normal digestion process, and coordinated activities of our body.

These are :
(1) Fat-soluble vitamins — A, D, E, K
(2) Water soluble vitamins — B complex and C

Question 129. What are minearls ? Write the role of minerals in human body.
Answer:
Minerals :
These are an inorganic element, occurring in the form of their salts.

Elements that are required in larger amounts for normal nutrition are called macroelements. Eg, C, H, N, O, P, Ca.

Elements which are reuiqred in very small amount for normal nutrition are called microelement. Eg, Iron, Copper, Zinc, Iodine.

Question 130. (1) Define excretion. How does it differ from secretion ?
Answer: The process by which living organisms get rid of their metabolic wastes from the body, through the excretory organs is called excretion.

Secretion is the process of discharge of essential substances from the cell, through the cell membrance for special function within the body is called secretion. Eg. enzyme from exocrine gland and hormones from endocrine glands.

(2) Why is excretion necessary ?
Answer:
(1) Excretory products are harmful to the body. So it is necessary to remove them.
(2) To maintain the contents of the protoplasm.
(3) Most of the plant excretory materials have great economic and medicinal importance. _
(4) To maintain water balance and osmotic equilibrium.

(3) Why is excretion a catabolic process ?
Answer:
(1) Formation of excretory products occurs by catabolic process (Break down).
(2) Elimination of metabolic waste products from the body takes place (wieght decreases).
(3) Result in decrease in dry weight of the organism.

Question 131. Name the excretory products in plants in tabular form with their uses.
Answer:
Non nitrogenous excretory products — Latex, Resin Tannin, gums, crystal, organic acids, essential oils.

Nitrogenous waste products — Alkaloids like Morphine, Quinine, Nicotine, Atropine, Reserpine, Caffeine, Thein etc. i

Non-nitrogenous waste products

Non-nitrogenous waste products

Question 132. What is the process of excretion in plants ?
Answer: There are no speical excretory organs in plants. The metabolic waste products are stored in root, stem, leaves, flowers and fruits. There is less formation of excretory products in plants and have no harm if stored in their body.
The process of excretion in plants are —
(1) Shedding of bark :
Plants like Arjun, Guava store their excretory products in the bark, and is eliminated at regular interval through the removal of bark.

(2) Shedding of leaves :
In deciduous plants metabolic wastes are transported and stored in the cells of leaves, and these wastes are eleminated by following of leaves. eg. Silk cotton, Sirish, etc.

(3) Shedding of flowers :
Metabolic wastes stored within the flower petals and also in the bract, are removed along with shedding of these organs

(4) Shedding of fruits :
Fruits like apple (malic acid), tamarind (tartaric acid), lemon (citric acid), removed by falling of fruits.

Question 132. “All excretory products are waste products but all waste products are not excretory products” Comment.
Answer: All excretory products are waste products but all waste products are not excretory products because they are toxic to the body and causes harm, if they store for longer time. Stool is not produced out of metabolism, hence it is not counted as an excretory substance.

Question 133. Name the excretory organs in animals.
Answer: The organs which are related to the removal of excretory products are called excretory organs

Different animals have characteristics of excretory organs as :
1. Contractile vacuole -—Amoeba, Paramecium, chlamydomonas
2. Flame cells               — Flatworm. A bunch of flame cells called protonephridia
3. Nephridia                 — Earthworm, Leach
4. Malpighian tubule   — Cockroach
5. Green gland             — Prawn
6. Kidney                     ___ Vertebrates (fish, amphibia, birds, reptiles, and mammals)
7. Scorpion                  — Coxal gland
8. Snail                         —- Nephridia

Question 134. Explain with diagram the excretory system of human.
Answer: The excretory system of human comprises two kidneys, two ureters, one urinary bladder and one urethra. A sphincter muscle is present at the junciton of Urinary bladder and Urethra, by which we can evacuate urine as our desire.

Each kidney is bean shaped, dark reddish brown in colour situated on the posterior portion of abdominal cavity on either side of vertebral column. Right kidney is slighly smaller than the left and the left is situated slightly above the right one. In adults its weight is 125-170 grms. The lateral margin is convex, while the medium margin has a concavity in the middle called hilum.

Internally each kidney is distinguished in two zones — an outer dark red zone — cortex and inner zone — medulla. Ureter entering through the hilum expands forming wide a funnel shaped str. called Pelvis which has at its free end, a number of cup like cavities called colyces. The inner border of medullary region is extended into a series of 15-16 cone like projections called renal pyramids. Fach kidney contains about
one million of nephron.

Functions of kidney :
(1) It excretes nitrogeneous and sulphur containing waste products of protein metabolism.
(2) It helpes in the osmo-regulation of the body.
(3) It helps to keep acid-base balance.
(4) It eliminates drugs and various toxic substances from the body.
(5) It regulates blood pressure.
(6) It helps in maintaining the osmotic pressure in blood and tissue.
(7) It plays an important role in Vit D metabolism.
(8) It synthesizes ammonia, hippuric acid and other substances.

Ureter :
Ureter are two in number 35 cm long, slightly curved tube, emerging from the renal pelvis. It connects kidney to the urinay bladder.

Urinary bladder and Urethra :
Urinary bladder is a muscular sac located in abdominal cavity. Urethra is a muscular tube that arises from bladder. Urinary bladder retains urine for some time when the bladder is full, the muscles of bladder contracts and urine goes out.

Question 135. What are Nephrons ? Write the structure and functions of nephron.
Answer:
Nephrons :
Nephron is the structural and functional unit of kideny. Each kidney consists millions of nephron. Average length of each nephron is 5 cm.

There are two types of nephrons :
(1) Superficial nephrons :
Present in the outer 2/3 of the cortex. They are smaller in size and constitute 85% of the total nephron. They work in normal condition.

(2) Juxtamedullary nephrons :
Present in the inner 1/3 of the cortex. They are larger in size and constitute 15% of total nephron. They work under stress condition.

Histologically, a nephron is made up of 2 parts, viz. Malpighian corpuscle and Renal tubule.

The free and blind end of nephron forms a cup shaped double walled structure called Bowman’s capsule. The outer layer of capsule is caled Parietal layer and the inner layer is called visceral layer.

Glomerulus :
It is a bunch of loop like capillaries ean eige within the Bowman’s capsule, formed by short and wide affarent arteriole (a branch of renal artery) and long and narrow efferent arteriole.

Malpighian corpusels forms the filtering bed and help in urine formation.

Renal Tubule is tubular portion of nephron.
(1) PCT :
descending tubule, highly coiled, situated in the cortical region of kidney. The inner wall is lined by cuboidal epithelium. It absorbs essential nutrients and huge amount of water.

(2) Henley’’s loop :
is U shaped middle portion, situated in the medullary region of the kidney. It absorbs water and electrolyte.

(3) DCT:
It is ascending tubule, situated in the cortical part of kidney: Inner wall is cuboidal epithelium. It reabsorbs sodium ion, water and bicarbonate.

Question 136. Write the steps of urine formation in human kidney.
Answer:
Urine formation involves three main steps :
Ultrafiltration, tubular reabsorption and tubular secretion.

(1) Ultra filtration (Glomerular ultrafiltration) :
The diameter of the afferent arteriole is double that of the efferent arteriole. Hence more blood comes in the glomerulus and less blood goes out of the glomerulus.

It creates a, pressure and causes filtration of various materials from blood. This process of filtration of blood is called ultrafiltration. The Glomerular Filtration Rate in normal healthy person is 125 ml/minute i.e 180 Ltr/day.

Tubular Reabsorption :
The glomerular filtrate contians many essential substances like phosphate, bicarbonate, chlorine ions, vit-C, amino acid, glucose, absorbed by the tublues. All these reabsorbed materials then return to blood. The process of tubular reabsorption is influened by hormone ADH and Aldosterone.

Tubular Secretion :
During urine formation, tubular cells secrete substances like H* K*and ammonia, creatinine, hippuric acid, penicillin, etc..These secretion, play an important in urine formation as it helps in the maintence of ionic and acid-base balance of body fluid.

Question 137. Write the role of Liver, Lungs and skin in the process of excretion.
Answer: Liver, lungs and skin are accessory excretory organs in human.

Role of Liver :
Within liver, ammonia is converted into Urea in ornithine cycle. Liver also secretes bile which containes some excretory substances like cholesterol, drugs, steroids and bile pigment-bilirubin and biliverdin which is eliminated front the body in the form of facaes.

Role of Lungs :
CO₂ which is produced by the catabolic process of glucose in the cells reacts with water to form carbonic acid (C₆H₁₂O₆ ). This CO₂ along with water vapour, alcohol, acetone, ammonia are excreted during expiration through the lungs.

Role of skin :
Normally skin is the protective layer of the body. It contains numerous sweat glands which secrete sweat. Sweat contains urea, lactic acid, creatinine, uric acid, salt, etc. These excretory products along with water are excreted. The sweat secretion also keep our body cool in summer.

Question 138. What is Urine ? Write the composition of Urine.
Answer: Urine is clear, yellow coloured weakly acid, aromatic watery solution of different metabolic wastes formed in the nephron of kidney.

Normally urnie consists 94.96% water, 4-6% of solids, Inorganic substances like Na, Cl, KCI, PO₄, SO₄, Ca, and organic substance like urea, uric, acid, creatinine, ammonia, hippuric acid, urochrome, oxalic acid, latic acid, ketone bodies, etc. are present.

Among abnormal constituents of urine are glucose, bile pigment, blood and pus, protein and ketone bodies.

11. Give an account of different essential oils produced from plants and their economic importance. 
Answer:

Question 139. State the importance of Excretion.
Answer:
Importance / Significance of Excretion :
1. Maintenance of normal health — The excretory products are harmuful to the body. Excess amount of excretory substances when accumulated in the body causes toxic effects or even may cause death to the organism. Thus regular excretion of these excretory products prevents from toxic effects and keeps body fit.
2. Maintenance of protoplasmic substances — Excretion has some role to maintain the balances of different protoplasmic substances in the cell, the protoplasm in turn helps to keep normal life processes of the organism.
3. Maintenance of osmosis — Excretion has some role on the regulation of osmosis.
4. Role in ecosystem — The excretory products are formed by the breakdown of nutrients.
5. Economic importances — The economic importances of excretory products of the plants are vast for human aswell as animal kingdom.
6. Maintenance of water balance — In various organisms mainly in animal and from human body excess amount of body water is excreted (eliminated) to maintain the water balance by this process.

Question 140. Why are lesser excretory materials formed in plant ?
Answer:
Reasons which cause lesser formation of excretory materials in plants:
1. Ammonia produced due to metabolism is utilized in the formation of various nitrogenous compounds by plants.
2. Carbon dioxide and water obtained due to respiration are used during photosynthesis. The oxygen obtained from photosynthesis is used in the respiration.
3. In plants the materials are formed.
4. In plant body the excretory materials which do not contain nitrogen are often stored within certain organs as they are not toxic.
5. In plant body the protein and nitrogenous compounds are broken down to ammonia which act as an useful substance.

From all these above reasons we can find that plant excretory products are less harmful than anumal excretory products.

Question 141. Write a note different excretory organs in animals with their functions.
Answer:
Different animals have characteristic excretory organ that has various shape, size and structure but perform same function of excretion as well as water balance of the body called osmoregulation some common examples of animal excretory organs are as follows :
(1) Contractile vacuole :
It is a subcellular membranous organelle, mainly found in protists (e.g. Amoeba, Paramoecium) and unicellular algae (e.g. Chlamydomonas), which primarily helps in osmoregulation.

Excess water is collected in the contractile vacuole and so the vacuole swells. Then the vacuole comes in contact with cell membrane, contracts and releases excess water out of the cell.

(2) Flame cell :
It is a specialized excretory cell found mainly in Platyhelminthes or flatworm (e.g. Taenia solium or Tape worm), that removes excretory product out of the body. Bunch of flame cells are together called as protonephridia.

Flame cell is a nucleated cup-shaped cell body with bunch of flagella inside that looks like flame of fire, Many flame cells are attached with common excretory canal. Collected excretory product from the cells is released in excretory canal and then goes outside.

(3) Nephridia :
This is the excretory as well as osmoregulatory organ found mainly in Annelida like earthworm, leech, etc. There are two basic types of nephridia — metanephridia (larger) and protonephridia (smaller). In earthworm, metanephridia is found.

In consists of ciliated funnel called nephrostome the collects excretory product from coelom. The product flows through nephridial tubule and finally goes out through nephridiopore. In the tubule, however, various necessary substances are reabsorbed,

(4) Malpighian tubule :
This is tubular excretory as well as osmoregulatory organ found in different Arthropoda (primarily in insects like cockroach and others).

These are bunch of slender tubules, located at the junction of midgut and hindgut. Most tubules are highly convoluted. The number tubules varies. These tubules collect excretory product from haemolymph and drain it into hindgut, from where the product moves through hindgut into rectum and finally goes out through anus.

(5) Kidney :
This is the most important excretory oragan in higher animals. All vertebrates have kindney. Like human kidney, they are made up of many nephrons (the structural and functional unit of kidney).

Kidney is mainly responsible for elimination of toxic metabolic waste product as well as osmoregulation, mineral balance and so on.

Question 142. What is blood ? What are the different components of blood?
Answer:
Blood :
Blood is a fluid connective tissue that circulate in the conducting vessels carrying nourishment and oxygen to all parts of the body and bringing metabolic wastes from them. It looks red due to the presence of an iron pigment namely haemoglobin.

Question 143. Define and exemplify universal donor and universal recipient blood groups.
Answer: The persons who can give blood to the persons having blood of any of the four blood groups is called universal donor. Example : ‘O’.

The person who can receive the blood from the persons having blood of any of the four blood groups is called universal recipient, e.g. the person having blood group ‘AB’
is called universal recipient.

Question 144. Why does the heart palpitate sometimes rapidly and sometimes very slowly ?
Answer:
The rate of heartbeat depends upon the following factors :
1. Quantity of blood,
2. Rate of respiration,
3. Emotional disturbance,
4. Systole and diastole of heart.

If the blood from left ventricle through the aorta abruptly increases or decreases, it will change the heart-beat accordingly.

The emotional disturbance and the release of hormones which in fluences the heart, obviously the heart-beat is altered. If the rate of respiration sharply increases, the
heart beat is effected, as 1 respiratory cycle under normal circumstances is equal to 4 cardiac cycles. We resipre 18 times per minute and the heart beats 72 times within the
same period.

Question 145. Why does the blood flow in the body of a vertebrate animal ?
Answer: Blood flows in the body of a vertebrate animal due to the rhythmicity of the heart. This can be explained as follows :

Blood flows in the body of a vertebrate animal due to the pumping action of the heart which acts as a double force pump. When the blood enters the right auricle (artrium) through superior and inferior venacavae, and the left auricle (atrium) through pulmonary veins, the systole movement (contraction) occurs in the both auricles which is initiated by the sinoauricular node (SA NODE) or the Pace-maker. The pacemaker than imparts kinetic energy to the blood which flows further. The presence of valves at different places prevent the back flow of blood. The presence of valves at different places prevent back flow of blood. The valves and kinetic energy maintain the unidirectional flow of the blood. Due to the regular rhythmic relaxation and contraction of the heart:the blood never stops and continues to flow.

Question 146. State the importance of circulation.
Answer:
Importance (Functions) of Circulation :
Circulation of blood acts mainly as ta support medium and helps the living body to perform several important functions as stated below :

(1) Transportation of nutrients — The digested food substances are absorbed from the digestive canal and carried by blood or lymph to all living body cells to provide nutrition.
(2) Transportation of respiratory gases — The oxygen (O₂ ) for respiration is carried from lungs to the tissue cells and carbon dixide (CO₂ ) produced in the tissue cells are carried by blood to the respiratory organs from where it goes out.
(3) Transpotation of enzymes and hormones — The enzymes, hormones, etc. are essential for proper functioning of the living body. They are synthesized and liberated from several sources and are carried by blood to the respective sites of action.
(4) Transportation of waste products — Various toxic metabolic waste products formed as a result of cellular metabolism are liberated out from the body through circulation.
(5) Helps in storage — The essential substances or other organic matters formed in excess within the living body are carried by circulation to the storage organs for future use.
(6) Maintenance of blood pressure — Blood circulation maintains blood pressure and thus regulates exchange of fluids and ions between blood and tissues.
(7) Transportation of minerals — Various minerals are transported by circulation from one part of the body to other.
(8) Generation of heat — By circulation the cells receive food (respiratory substrate) and O₂ and then the cells produce heat energy by respiration.

Question 147. What is coagulation of blood ? What are the fectors involved in it ? Briefly describe the process of blood coagulation.
Answer:
1. The process by which blood oozing out from the ruptured blood vessels loses its fluidity in a few minutes and sets into a semi solid jelly-like mass, is called coagulation.

2. Factors involved in blood coagulation :
Blood coagulation is a complex process which requires about 13 factors. All these factors are present in plasms except factor Ill (thromboplatin). Except factor IV (calcium ion) all other factors are protein in nature. Some important factors are — Factor | (fibrinogen), Factor II (prothrombin), Factor Ill (thromboplastin), Factor IV (Ca⁺⁺) and son on.

3. Process of blood coagulation :
It taken place in three steps —
(1) When blood comes out of an injured area, the platelets come in contact with ruptured blood vessels (rough surface). The platelets are broken in the presence of several clotting factors of blood and produce intrinsic thromboplastin.
Thromboplastin is also produced from the damaged tissue cells (extrinsic thromboplastin or tissue thromboplastin) in presence of Ca⁺⁺ and other factors.
(2) Prothrombin of plasma is converted to thrombin in the presence of Ca ⁺⁺ and thromboplastin.
(3) Thrombin reacts with soluble fibrinogen to convert it into insoluble fibrin. In the mesh work of fibrin fibres, the blood corpuscles are entangled forming a plug which is called clot.

Equations:
1. Normally in circulating blood :
Platelets + Prothrombin + Fibrinogen —> no clot

2. After shedding of blood :
                                                              Releasing
(1) Broken platelets or damaged tissues ——-> Thromboplastin.
Ca⁺
                         Thromboplastin
(2) Prothrombin ———–> Thrombin.
                                      Thrombin
(3) Fibrinogen Fibrin (clot). ———-> Fibrin (clot).

Question 7. Classify body fluids on the basis of fluid compartments.
Answer:
Fluid Compartments :
Body fluids can be discussed in terms of their care
fluid compartment, a location that is largely separate from another compartment by some form of a physical barrier. The intracellular fluid (ICF) compartment is the system that includes all fluid enclosed in cells by their plasma membranes. Extracellular fluid (ECF) surrounds all cells in the body. Extracellular fluid has two primary constituents the fluid component of the blood (called plasma) and the interstitial fluid (IF) or tissue fluid that surrounds all cells not the blood.

Intracellular Fluid :
The ICE lies within cells and is the principal component of the cytosol/ cytoplasm. The ICF makes up about 60 per cent of the rotal water in the human body. This fluid volume tends to be very stable, because the amount of water in living cells is closely regulated.

Extracellular Fluid :
The ECF accounts for the other one-third of the body’s water content. Approximately 20 per cent of the ECF is found in blood plasma. Plasma travels through the body in blood vessels and transports a range of materials, including blood cells, proteins (including clotting factors and antibodies), electrolytes, nutrients, gases and wastes. Gases, nutrients and waste materials travel between capillaries and cells through the IF. Cells are separated from the IF by a selectively permeable cell membrane that helps regulate the passage of materials between the IF and the interior of the cell.

The body has other water-based ECF. These include the cerebrospinal fluid that bathes the brain and spinal cord, lymph that helps in transport and immunity, the synovial fluid in joints which helps in mobility, the pleural fluid in the pleural cavities, the pericardial fluid in the cardiac sac, the peritoneal fluid in the peritoneal cavity,
and the aqueous humor of the eye. Because these fluids are outside of cells, these fluids are also considered components of the ECF compartment. Fluid is lost from our body through urine, sweat, etc.

Chapter 3 Physiological Processes Of Life Difference Type Questions

1. Photosynthesis and Respiration:—

2. Respiration and Breathing:-

3. Aerobic Respiration and Anaerobic Respiration:-

4. Respiration and Combustion:—

5. Anaerobic Respiration and Alcoholic Fermentation :—

6. Aerobic Respiration and Combustion :-

7. Anaerobic Respiration and Fermentation:-

8. Aerobic Respiration and Fermentation :—

9. Plant Respiration and Animal Respiration :—

10. Plant Nutrition and Animal Nutrition :—

11. Fat and Protein :—

12. Autophytes and Heterophytes :—

13. Parasite and Saprophyte :—

14. Parasite and Saprotroph :—

15. Parasite and Heterotroph :—

16. Anabolism and Catabolism :—

17. Digestion and Assimilation :—

18. Autotrophic and Heterotrophic:-

19. Autotroph and Heterotroph:—

20. Vitamin and Enzymes:—

 

21. Enzymes and Hormones :—

22. Essential element and Trace element :-

 

23. Vein and Artery :—

 

24. Haemoglobin and Haemocyanin :—

 

25. Structural Difference between Vein and Artery :-

26. Functional difference between Vein and Artery :—

27.Lymphocyte and Thrombocyte :-

28. Open Circulation and Close Circulation:—

 

29. Erythrocyte and Leucocyte :—

30. Erthryocyte in man  and Leucocyte in man:-

31. Blood and Lymph:—

32. Mammalian R.B.C. and R.B.C of Other Vertebrates :-

• Chapter 1 Life and Its Diversity
• Chapter 2 The Levels of Organization of Life
• Chapter 4 Biology and Human Welfare
• Chapter 5 Environment and its Resources

Chapter 2 Levels Of Organization Of Life Very Short Answer Questions

Question 1. Name two prokaryotic cells.
Answer: Bacteria and Blue-green algae.

Question 2. Name two trace elements of protoplasm.
Answer: Iron and Manganese.

Question 3. Name two types of essential secretory products of protoplasm.
Answer: Zymogen and. Hormones.

Read and Learn more about WBBSE Solutions for Class 10 Life Science And Environment

Question 4. Name two components of bacterial cell walls which are not present in the cell walls of higher plants.
Answer: Mucopeptide and Peptidoglycan.

Question 5. State the function of the centriole.
Answer:
(1) originate cilia and flagella.
(2) formation of a spindle during cell division.

Question 6. Where are the chlorophyll molecules concentrated in the chloroplast?
Answer: Quantasomes present in thylakoids.

Question 7. Name one single-layered membrane organelle in the cell.
Answer: Golgi body and Lysosome.

Question 8. What is a tonoplast?
Answer: Outer covering of central vacuole of a mature plant cell.

Question 9. Name one plant cell and one animal cell where the nucleus is absent.
Answer: Plant cell — Sieve tube, Animal cell — matured mammalian RBC.

Question 10. What is the function of dictyosome?
Answer: It is the Golgi body of plant cells and helps.in secretory process.

Question 11. Which organelle connects the cell membrane with the nuclear membrane?
Answer: Endoplasmic reticulum.

Question 12. Name the plant cell visible to the naked eye.
Answer: Root hair cell, fibre cell of jute.

Question 13. What is plasmodesmata ?
Answer: Cytoplasmic bridges between adjacent plant cells. They help to maintain the continuity of cytoplasm between two adjacent cells.

Question 14. What is glycocalyx? 
Answer: It is an external covering present around the plasma membrane of some animal cells, made up of glycoprotein. :

Question 15. What is cytosol?
Answer: Cytoplasmic matrix.

Wbbse Class 10 Life Science Solutions

Question 16. Name a cell where mitochondria are present in large numbers.
Answer: Liver cells, cardiac muscle cells.

Question 17. Name two animal cells containing more than one nuclei.
Answer: Skeletal muscle cells and Paramecium.

Question 18. What is cell sap?
Answer: Cell sap is the fluid present within the vacuole, containing water, salt and enzymes.

Question 19. Name the membrane on which epithelial tissue rests.
Answer: Basement membrane.

Question 20. Name the tissue which lacks blood vessels.
Answer: Epithelial tissue.

Question 21. Give the name of one inflammatory protein stored by mast cells.
Answer: Histamine.

Question 22. Which tissue synthesises, stores and metabolises fat?
Answer: Adipose tissue.

Question 23. Name the tissue which connects a bone to another bone.
Answer: Ligament.

Question 24. Name the tissue where Haversian canals are found.
Answer: Bones.

Question 25. Mention the site of haemoglobin synthesis.
Answer: Red Bone marrow of long bones.

Question 26. Which pigment is formed when haemoglobin is catabolised?
Answer: Bilirubin.

Wbbse Class 10 Life Science Solutions

Question 27. What is polycythemia?
Answer: Abnormal increase in the number of RBCs.

Question 28. Name the type of epithelium that bears microvilli for absorption.
Answer: Brush-bordered cuboidal epithelium.

Question 29. Name two fluids found in the body.
Answer: Blood and lymph.

Question 30. Name the tissue which fills the gap between the organiser:
Answer: Connective tissue.

Question 31. Name the type of epithelium that lines the inner surface of the stomach.
Answer: Simple columnar epithelium.

Question 32. What are Kupffer cells?
Answer: The phagocytic cell is found in the liver.

Question 33. What is Rigor mortis?
Answer: Muscles become rigid after death.

Question 34. What are tendons?
Answer: A band of collagen fibres which joins the skeletal muscle to the bone.

Question 35. Which type of food fulfils the requirement of nitrogen in the animal body?
Answer: Protein

Wbbse Class 10 Life Science Solutions

Question 36. Name the disease which is caused by the deficiency of vitamin A.
Answer: Xerophthalmia.

Question 37. Name a vitamin that is dissolved in a fatty substance or fat.
Answer: Vitamin A.

Question 38. Name a vitamin which is solubilized in water.
Answer: Vitamin B.

Question 39. Deficiency of which vitamin causes an interruption in. blood coagulation?
Answer: Vitamin K.

Question 40. Deficiency of which vitamin causes rickets?
Answer: Vitamin D.

Question 41. Which vitamin is obtained from sour fruits? Give deficiency symptoms of this vitamin.
Answer: Vitamin C. Its deficiency causes Scurvy.

Question 42, What is a nucleotide?
Answer: Nucleotide is the structural unit of nucleic acid (DNA and RNA). Deoxyribonucleotide is the structural unit of DNA and ribonucleotide is the structural unit of RNA.

Question 43. Mention the main two types of tissue.
Answer: Two types of plant tissue are meristematic tissue and plant tissue.

Question 44. Name the tissue which is present at the apex of the stem.
Answer: Meristematic tissue.

Question 45. Name any two types of simple tissue.
Answer: Parenclyma and collenchyma are two types of simple permanent tissue.

Question 46. Name the parenchyma tissue containing air.
Answer: Aerenchyma cells contain air cavities.

Question 47. Name the parenchyma tissue containing chlorophyll.
Answer: Chlorenchyma cells contain chlorophyll.

Question 48. Name the simple tissue whose corners are thickened without intercellular spaces.
Answer: In Collenchyma corners are thickened without intercellular spaces.

Wbbse Class 10 Life Science Solutions

Question 49. Name the dead simple permanent tissue.
Answer: Schlerenchyma is the dead simple permanent tissue.

Question 50. Name the largest organ of the human body.
Answer: The skin is the largest organ of the human body.

Question 51. Name the acid present in the stomach.
Answer: Hydrochloric acid.

Question 52. Where is the pancreas located?
Answer:
Function :
(i) Processes all sensory information and generates responses accordingly.
(ii) Act as the centre for memory, intelligence, thinking and all other mental activities.

Question 53. Mention one function of the liver.
Answer: It synthesizes bile, stores glycogen, and helps in detoxification.

Chapter 2 Levels Of Organization Of Life Short Type Questions And Answers

Question 1. Name the type of enzyme present in mitochondria and lysosomes.
Answer:
In Mitochondria — Oxidative enzymes
In Lysosomes — Hydrolytic enzymes

Question 2. Define cell.
Answer: The term cell was first used by Robert Hooke (1665). The cell is the structural and functional unit of all living organisms.

The branch of biology which deals with the study of the structure of cells is called cytology.

Question 3. Name the smallest and the largest plant cell and animal cell.
Answer:
Smallest cell — Mycoplasma gallisepticum
Longest plant cell — Phloem fibre of Ramie plant
Longest animal cell — Mammalian Neurone.

Question 4. Differentiate between organ and organelle.
Answer: Organs are structural components of multicellular plant and animal bodies. They are macroscopic structures.

Organelle are structural components of a cell and are microscopic.

Question 5. What is cell theory?
Answer: Cell theory was proposed by Schleiden and Schwann (1839).
(1) All organisms—animal or plants—consist of cell
(2) Cells are of universal occurrence and are the basic unit of an organism.
(3) All cells are produced from the pre-existing cells.

Cell shape and size :
The shape of the cell differs in different organisms. It may be round, cylindrical, cuboid, columnar or thread-like. The cells are mostly microscopic. The smallest cell is a pleuropneumonia-like organism (PPLO). The largest cell is the egg of the ostrich. In mammals, the nerve and muscle cells may reach up to 900 mm in length.

Question 6. What are the exceptions to cell theory?
Answer:
(1) Viruses without cellular organisation
(2) Prokaryotes without true cellular structure
(3) Mucor, Rhizopus and Vaucharia do not conform to the normal definition of cell.

Wbbse 10th Class Life Science Question Answer

Question 7. Classify animal tissue.
Answer: Depending on the structure and function, the animal tissue is classified into 4

types :
1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue.

What are essential amino acids?
Answer:
Essential amino acids :
Several nutritionally important amino acids are not synthesized inside a living body. These are to be taken with dietary proteins. Such amino acids are called essential amino acids. These are methionine, tryptophan, histidine, phenylalanine, valine, threonine, lysine, leucine, and isoleucine.

Question 8. What are polysaccharides?
Answer:
Polysaccharides :
These are large carbohydrates, composed of more than ten monosaccharide units. The basic molecular formula of polysaccharides is (C₆H₁₀O₅)_n. They are generally insoluble in water and not sweet to taste.

Examples: Starch, cellulose (found in plant cells), glycogen (found in animal cells), chitin (found in insect bodies), etc.

Question 9. Name two animal sources and two plant sources of fat type of food.
Answer:
Source :
1. Plant source — Mustard oil, coconut oil, groundnut oil, etc.
2. Animal source — Meat, milk and milk products like ghee, butter, cheese, etc.

What is fat or lipid?
Answer: Eat is the ester of fatty acid and glycerol. The salt of alcohol (glycerol) with organic acid (fatty acid) is known as ester. Lipid is a broad term which includes fat, wax, cholesterol, and hydrocarbon since all of them are insoluble in water but soluble in organic solvents.

Question 10. What is a vitamin?
Answer: Vitamins are smaller biomolecules, required in small amounts, for normal functioning of the body and provide resistance against some diseases. These act as coenzymes in several enzyme-dependent metabolic reactions.

Question 11. Name fat-soluble and water-soluble vitamins.
Answer:
(1) Fat-soluble vitamins (vitamins A, D, E, K) and
(2) Water-soluble vitamins (vitamin C and B complex).

Question 12. Which vitamin is known as an antihaemorrhagic factor?
Answer: Blood clotting — It takes part in the manufacture of prothrombin (clotting protein factor of blood in plasma) in the liver and helps in normal blood coagulation.

Wbbse 10th Class Life Science Question Answer

Question 13. State three characteristics of meristematic tissue.
Answer:
Characteristics :
(1) Cells are living, undifferentiated, polygonal, spherical or oval in shape.
(2) Cells are densely packed with no intercellular spaces.

Question 14. Mention the functions of the xylem.
Answer:
Function :
(1) Xylem helps in transportation of water and solutes undirectionally.
(2) Acts as supportive tissue, imparting mechanical strength to the plant body.
(3)Helps in the storage of water and mineral salts.

Question 15. Mention the functions of phloem.
Answer:
Functions :
(1) Conduction of food — by sieve tubes of phloem both in upward and downward directions.
(2) Storage of organic food matters.
(3) Lateral translocation of food by the companion cells.

Question 16. State two structural features of permanent tissue.
Answer:
Characteristic features :
(1) Intercellular space may be present in between the cells.
(2) Cells may or may not contain protoplasm and, hence may be living or dead.

Question 17. State two structural features of epithelial tissue.
Answer:
Structure :
(1) Cells are present on a basement membrane made of connective tissue.
(2) Cells are densely packed & joined together by microproteins.

Question 18. State two functions of connective tissue.
Answer:
Function :
(1) Areolar tissue acts as packing material between organs
(2) Adipose tissue stores fat for future use, keeps the body warm and protects it from mechanical injury.

Question 19. State two structural features of muscular tissue.
Answer:
Structure :
(1) Cells are elongated, cylindrical or spindle-shaped.
(2) Bundles of muscle fibres, surrounded by connective tissue, constitute a muscle.

Wbbse 10th Class Life Science Question Answer

Question 20. Mention two functions of the Brain.
Answer:
Function :
(1) Processes all sensory information and generates responses accordingly.
(2) Act as the centre for memory, intelligence, thinking and all other mental activities.

Chapter 2 Levels Of Organization Of Life Descriptive Type Questions And Answers :

Question 1. What are biomolecules?
Answer: Building block molecules are called biomolecules. They make up the body of organisms, cells and cell organelles.

It is of two types —
(1) Micro-molecules :
Small molecule size with low molecular weight, eg. minerals, water, gases, carbohydrate, etc.

(2) Macro-molecules :
Large molecule size with high molecular weight. It is formed by polymerisation of many micro-molecules of one type.

eg: Protein, Polysaccharides, Nucleic acid.

Question 2. What is the average composition of plant and animal cells?
Answer:

Question 3. Write the roles of inorganic compounds in the body of living organisms.

Answer:
Water :
It is the most abundant inorganic compound in living organisms. On an average, water forms 65-75% of protoplasm.

It acts as a solvent for all soluble substances in the cell. It provides an aqueous medium for various cellular reactions. It provides proper hydration to protoplasm. It provides turgidity to the cells in plants. Water maintains constant body temperature in plants and animals. Water acts as a source of hydrogen in photosynthesis.

Gases :
The main gases which play an important role in metabolism are O₂ and CO₂. Oxygen is needed for the aerobic breakdown of organic food and the release of energy for life. Carbon dioxide is used by photosynthetic autotrophs for the synthesis of carbohydrates.

Question 4. What are carbohydrates? Write their functions.
Answer: Organic compounds containing carbon, hydrogen and oxygen. Its general formula is Cn(H₂O)n. Based on the number of sugar Units in the molecule, it is classified as

(1) Monosaccharides :
Contain only one sugar unit known as glucose or simple sugar. These are the reducing agents.
Eg. Glucose (C₆H₁₂ O₆)

(2) Oligosaccharides :
Carbohydrates with 2-9 mono-saccharides joined together.
glucose + glucose -» Maltose
glucose + fructose -» Sucrose
glucose + glucose -— Lactose~

(3) Polysaccharides :
Carbohydrate with 10 or more mono-saccharide units. These are macro-molecules.
Eg: Starch and cellulose.

Wbbse 10th Class Life Science Question Answer

Functions :
(1) These are structural components.
(2) Play an important role in metabolic functions.
(3) Act as a potential source of energy in cells.

Question 5. What are Amino Acids and proteins? Write their functions.
Answer: Amino acids are microbiomolecules with low molecular weight. They contain C, H, O and N, S.

These are essential and non-essential amino acids.

Essential amino acids are 8 in number. These are not synthesized in animal cells and obtained through diet only, eg. Valine, Leucine, Methionine, Lysine etc.

Non-essential amino acids are 10 in number and are naturally synthesized in the body.

eg. Alanine, Arginine, Aspartic acid, Serine.

Semi-essential Amino Acid :
Only 2 in number can be synthesized in animal cells but not enough. Eg. Arginine and Histidine.

Amino Acids are used in protein synthesis, glucose, vitamins and hormone synthesis.

Question 6. Write the structure and functions of the protein.
Answer: These are long-chain polymers of amino acids with very high molecular weight. It contains C, H, O, N, S and P. The bond which joins two amino acid molecules is a peptide bond.

Types of protein :
(1) Simple protein :
made of only amino acids, eg: albumin, and histone.

(2) Conjugated protein :
made of amino acid + some non-protein group.

Example: Nucleoprotein, Glycoprotein.

(3) Derived protein :
These are intermediate degradation products of protein, obtained on the hydrolysis of protein.

Functions of Protein :
(1) These are structural constituents of protoplasm, protoplasmic organelles and cell membrane.
(2) Enzymes are proteins, essential for metabolism.
(3) Cytochrome pigment helps in photosynthesis and Respiration.
(4) Haemoglobin transports oxygen in the body.
(5) Actin and myosin help in muscle contraction.
(6) Fibrinogen and thrombin help in blood clotting.

Question 7. Write the structure and functions of lipids in the human body.
Answer: Lipids are oily, greasy organic compounds, insoluble in water. Lipid molecule contains C, H, O. It has less percentage of oxygen.

These are :
(1) Simple lipids :
These are esters of fatty acids with alcohol.

eg. Bees wax, cholesterol.

Wbbse 10th Class Life Science Question Answer

(2) Compound lipids :
These are fatty acids + Alcohol + Some other group.

eg. Phospholipid, Glycolipid, Steroids Carotenoids.

Functions of lipids:
(1) Release more energy than carbohydrates.
(2) Constituent of cell membrane.
(3) Acts as a solvent for fat-soluble vitamins.
(4) Acts as insulator.

Question 8. What are Nucleotides and Nucleic Acids?
Answer:
Nucleotides :
Nucleotides are the building block unit for Nucleic acid. These are macromolecules with low molecular weight.

Nucleotide = Pentose Sugar + Nitrogenous base + Phosphate group.

Nucleic Acid:
These are long-chain polynucleotide macromolecules. These are the most important biomolecules and control most biological processes, including heredity.

There are two types of Nucleic acid: DNA and RNA.

DNA (Deoxyribose Nucleic Acid): Double-stranded helical structure. Two strands are antiprallel_ and coiled around each other. Complementary base pairs are :

Adenine is attached to thymine with a double hydrogen bond and Guanine with cytosine with a triple hydrogen bond. DNA has the unique ability of self-replication.

Functions of DNA:
(1) It is the genetic material of all organisms (except some viruses).
(2) It takes part in genetic recombination.
(3) It can replicate itself.

RNA (Ribose Nucleic Acid) :
Single-stranded, long-chain polynucleotide. Complementary base pairs are — Adenine, Guanine, Cytosin, and Uracil. These are mainly present in cell cytoplasm.

Types :
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)

Functions :
(1) Involved in protein synthesis.
(2) In certain viruses acts as the genetic material.

Question 9. What are vitamins? Write their roles in the human body.
Answer:
Vitamins :
Vitamins are complex organic chemicals that are present in our
food in small quantities. Vitamins are essential for growth, good health, proper vision, normal digestion process and co-ordinate activities of our body.

These are :
(1) Fat-soluble vitamins — A, D, E, K
(2) Water soluble vitamins — B complex and C

Question 10. What are minerals? Write the role of minerals in the human body.

Answer:
Minerals :
These are an inorganic element, occurring in the form of its salts. Elements which are required in larger amounts for normal nutrition are called macroelements. Eg, C, H, N, O, P, Ca.

Elements which are required in very small amounts for normal nutrition are called microelements. Eg, Iron, Copper, Zinc, Iodine.

Question 11. Write the structure and function of the cell wall.
Answer:
Cell Wall :
Present in plant cells, fungi and bacteria but absent in an animal cell. It is a non-living, rigid covering, external to the plasma membrane. A cell wall differentiated into middle lamella, primary cell wall and secondary cell wall. There are minute pores on the cell wall, through which cytoplasmic continuity is established between the adjacent cells. Their cytoplasmic bridges are called Plasmodesmata. The middle layer is made up of pectin and some amount of protein. The primary cell wall is thin and permeable, composed of cellulose. The secondary cell wall is also made up of cellulose with hemicellulose, pectin and lignin.

Functions:-
(1) Provides cell its shape.
(2) Protect the cell membrane and cell content.
(3) Prevents the drying of a cell
(4) Provides mechanical support to the cell
(5) Helps in the maintenance of osmotic balance.

Question 12. Write the structure and functions of the cell membrane.
Answer:
Cell membrane — (Plasma membrane)
The thin, elastic and semi-permeable living membrane that surrounds the protoplasm of a cell.

Nageli and Cramer (1856) reported about the existence of it. Plowe (1931) named it as plasmalemma.

Structure :
Singer and Nicholson (1972) showed that the membrane is formed of two phospholipid layers with distinct surface proteins and integral proteins in between. The name given is the Fluid Mosaic Model. The point of attachment of the cell membrane of two cells is known as a desmosome.

Spherical hydrophilic polar heads of lipids are directed towards the two surfaces of the membrane. The hydrophobic tails of lipids are directed inwards.

Functions :
(1) It denotes the shape of an animal cell.
(2) It protects the cytoplasm.
(3) It helps in the intercellular transport.
(4) It helps in diffusion and osmosis between cells.
(5) It helps in cell eating and cell drinking by phagocytosis and pinocytosis.
(6) Seletive permeability.
(7) Help in maintaining homoeostasis in the cell.

Question 13. What is Cytoplasm?
Answer: Occupies cell space in between plasma membrane and nucleus. It is a part of protoplasm. It is a jelly-like, colloidal matrix and the seat of all metabolic activities of the cell.

It consists of protein, fats, carbohydrates, hormones, vitamins, nucleic acid, protoplasmic cell organelles and vacuoles. Non-living substances in cytoplasm represent deutoplasm. San

Functions:-
(1) It acts as a matrix for cell organelles.
(2) It controls the different metabolic activities within the cell.
(3) It maintains coordination between the different organelles within the cell.
(4) It is sensitive to external stimuli.

Question 14. Explain with a diagram the structure and function of the nucleus.
Answer:
Nucleus :
The membrane-bound central controlling organelle of the cell carrying
the genetic information is known as the nucleus. Robert Brown (1833) first described the nucleus. It is present in all living cells except matured RBC in human body and sieve tube of plant cell. A multinucleated plant cell is called a Coenocytes and a multinucleated animal cell is called Synctium.

The nucleus is differentiated into the Nuclear envelope, Nucleoplasm; Nuelear reticulum and Nucleolus.

(1) Nuclear envelope :
Double cytoplasmic membrane with many ee pe membrane nuclear pores having definite ribosome organization. The two layers are ~ Diagrammatic structure of nucleus separated by Perinuclear space.

Functions :
(1) Transport and exchange of materials between nucleus and cytoplasm.
(2) It separates nucleoplasm from cytoplasm.
(3) Maintains definite shape of the nucleus.
(4) Ribosomes attached to the cuter face of the envelope are involved in protein synthesis.

(2) Nucleoplasm :
The transparent, jelly-like matrix within the nucleus is called a nucleoplasm. It is also called karyolymph. It fills the internal space of the nucleus. Consists of more than 90% protein. It stores food and enzymes.

(3) Nuclear Reticulum :
It consists of DNA and histone protein. Exists as a chromatin
network in the interphase nucleus. During cell division, it condenses into distinct Chromosomes. Chromosomes are formed of genes which carry the characters from one generation to the next.

(4) Nucleolus :
The spherical dense body inside the nucleus. It consists of granular
part, fibrilar part, matrix and chromatin body. It is usually formed by the aggregation of the Nucleolar Organizer Region (NOR) of the chromosomes.

Functions :
(1) Help in cell division.
(2) Production of ribosomes.

Question 15. Why is mitochondria called the powerhouse of a cell?
Answer:
Mitochondria :
Highly specialized double membrane-bound organelles are present in the cells of higher plants and animals. Kollicker (1850) first observed mitochondria. Altman (1892) called them bioplast. Benda (1897) proposed the name mitochondria. Hogeboom (1948) confirmed mitochondria as the seat of aerobic respiration. It is present only in Eukaryotic cells except in matured RBCs of mammals. The inner membrane is thrown into finger-like projections called cristae. The matrix contains enzymes for the TCA cycle reaction. Cristae is the site for terminal oxidation, ATP formation, utilization of oxygen and formation of water.

Functions :
(1) It is known as the powerhouse of a cell because it produces and stores energy in the form of ATP.
(2) It helps in the metabolism and the breaking of fat molecules.
(3) It also produces certain respiratory enzymes.

Question 16. Write the structure and function of the Endoplasmic Reticulum.
Answer:
Endoplasmic Reticulum :
It is a network of double membranes distributed all over the cytoplasm. The tubules or vesicles are interconnected. It connects the nuclear membrane with the plasma membrane. It exists in different forms like Cisternae, Tubular ER and Vesicular ER.
ER is of two types :
(1) Rough Endoplasmic Reticulum has ribosomes attached to its surface.
(2) Smooth endoplasmic reticulum (SER) when the walls of tubules are smooth without ribosomes.

Functions :
(1) Mechanical support
(2) Maintenance of osmotic pressure
(3) Exchange of materials
(4) Protein synthesis
(5) May help in the storage of certain components.
(6) They divide the cell into different components.

Question 17. Explain the structure and functions of the Golgi body.
Answer:
Golgi body :
They are single membrane-bound flattened sac-like structures, present in animal cells.

In plant cells, they remain scattered and are called dictyosomes. It is discovered by Camilo Golgi (1890).

They include flattened sac-like cisternae, small round vesicles and larger vacuoles. They contain various secretory enzymes.

Function :
(1) Help in the secretory activities of the cell.
(2) They store protein and enzymes.
(3) They are from the acrosome of spermatozoa.
(4) Help in intercellular transport.
(5) It activates mitochondria.

Question 18. What are lysosomes and ribosomes? Write their functions.
Answer:
Lysosomes :
Their cell inclusions are characteristics of an animal’s cell. They have an outer membrane and their origin is from vesicles derived from the Golgi complex. Lysosomes contain hydrolytic enzymes. They -— Granular are abundant in WBC that bring phagocytosis ‘ Se of bacterial cells. Lysosomes are denoted by oe Cade Duve (1955). Lysosome performs four main functions:
(1) Extracellular digestion Structure of lysosomes
(2) Intracellular digestion
(3) Self digestion
(4) Digestion of substance outside the cell. They act as suicidal bags and help in the destruction of worn-out cells.

Ribosomes:
There are very minute spherical bodies found closely associated with ER. They contain ribosomal RNA and protein. They are formed from nucleolus and denoted by Robinson and Brown (1953) and Palade (1955). In prokaryotes, they are 70 s E Tanverse with two subunits 50S and 30S respectively, while depression in Eukaryotes, they are 80S with two subunits I Subunit (40S) 60S and 40S. (S for Swedberg unit). They remain in a chain called Polysome)

Function :
Synthesizing protein helps in lipid metabolism.

Vacuole :
There are empty spaces within Subunit protoplasms filled with cell sap or gases. More (605) common in plant cells. These may contain water, inorganic salt, organic material, etc.

It helps in osmoregulation by regulating the water content in the body. It also helps in the storage and digestion of food and excretion in unicellular organisms like Amoeba.

Question 19. What are centrosomes microsomes and microtubules? Write their functions.
Answer:
Centrosome :
The star-like organelle, very Centrosome close to the nucleus of an animal cell is called a centrosome. It consists of a pair of centrioles and the centrosphere surrounding it. Each centriole is cylindrical and open at both ends. The wall of each cylinder is made of 9 microtubules.

Functions of Centrioles :
(1) Give rise to basal bodies of cilia and flagella.
(2) Play an important role in cell division, forming spindle apparatus.
(3) It forms the tail of sperm in higher animals.

Microtubules :
Hollow unbranched tubules, made of sub-units of protein tubulin.
1. It provides polarity to cells.
2. Involved in cell movement.
3. Help in intracellular transport.

Question 20. What are plastids? Name and explain different types of plastids.
Answer:
Plastids :
Membrane-bound cell organelles are present only in plant cells. The term was denoted by Schimper (1883).

It is formed from a primitive plastid called Proplastid. It is of three types :

Chloroplast :
Green-coloured plastid containing green pigment chlorophyll. It is present in leaves and other green parts of the plants. They are formed of two distinct parts, the stack-like granum and ground substance stroma. Each granum is formed of an individual sac-like structure called a thylakoid. Each thylakoid is a membrane-bound flattened vesicle. Thlaokoid membrane contains photosynthetic pigment, electron carriers, and co-enzymes organised into Quantasome. It helps in trapping light energy and synthesis of ATP.

Functions :
(1) Site of all photosynthetic reactions.
(2) Responsible for conversion of light energy to chemical energy.
(3) Synthesis of Carbohydrate from CO₂, and H₂O.

Chromoplasts :
Coloured plastids other than green are present in the flowers of plants. They contain carotene and xanthophyll.

Function :
(1) They help in insect pollination.
(2) They absorb the extra wavelength of the sun and help in photosynthesis.

Leucoplaslids :
Colourless plastids are remaining in the underground parts of the plants. It contains stored food and some enzymes. They are classified into three types based on the food they store.

Amyloplast (Storing carbohydrates), Aleuroplast (storing protein), and Elaioplast (storing fats).

Question 21. Differentiate between Prokaryotic and Eukaryotic.
Answer:

Question 22. Differences between plant cells and animal cells.
Answer:

Question 23. What is epithelial tissue? Name the different types of epithelial tissue. Write their functions.
Answer:
Epithelial Tissue :
The cells lie close together and are held together by all junctions, with little or no extracellular material. This type has one free surface, the other surface rests on the basement membrane. The blood vessels are absent.

Question 24. Write the function and location of nervous tissue.
Answer:

Question 25. What is muscular tissue? Name its types and functions.
Answer:

Question 26. Differences in bones and cartilage :
Answer:

Question 27. What is connective tissue? State the location and function of different types of connective tissue.
Answer:

Question 28. Write the differences between blood and lymph.
Answer:

Question 29. Differentiate between striated and smooth muscle.

Answer:

Question 30. Differentiate between Tendons and Ligaments.

Answer:

Question 31 What is a tissue?
Answer:
Tissue :
A tissue may be defined as a group of cells having common origin,similar structure and function being held together by a cementing substance.” The study of tissue is called histology.

In higher multicellular organism, however, although each cell can carry on all fundamental, vital, biological processes, it is not capable of independent existence. The cells of multicellular organism interact and cooperate with one another. For example, a muscle cell in man could not obtain food or oxygen on its own.
Cell —> Tissue -> Organ —> Organ system —> Individual

Question 32. What are Meristematic tissue ? Write its characteristics.
Answer:
Meristematic tissue :
It consists of a group of cells which have the capacity to divide. This tissue is found at all growing points of a plant such as tips of root, stem and branches. It is also present between the bark and the wood of trees where it leads to the growth in the diameter of stem.

Characteristics :
1. Cells are small, usually cubical.
2. The cell walls are thin and large nucleus, densely cytoplasm.
3. Vacuoles are almost absent.
4. Cells are tightly packed with no intercellular spaces.
5. The cells actively divide, adding new cells to the plant.
6. New cells thus produced are transformed into mature permanent tissue.

According to location, meristems are :
1. Apical meristem — It is present at the apices of the root stem and other growing organs and helps in growth in length.
2. Lateral meristem — It is present in a circle parallel to epidermis of stem and root. It help in growth in diameter, e.g. cambium and Be cork cambium.
3. Intercalary meristem — It is present within permanent tissue in the internodal region of the stem. It helps in growth in length.

Question 33. What are permanent tissue? Describe with diagram its types and functions.
Answer:
Permanent Tissue :
Permanent tissue is made up of cells poses s’merstem. which have lost their ability to multiply. They take a permanent shape to perform some permanent functions. These may be simple or complex. These cells are either living or dead and thin walled or thick-walled.

Simple Permanent Tissue :
It is made up of one type of cells forming a uniform mass. On the basis of cell types, it is of three kinds :

(1) Parenchyma:
It is made up of living, usually isodiametric cells. The cell wall is thin and consists of cellulose, pectin and hemicellulose Intercellular eae usually runs between the cells.

Parenchyma are the ground tissue of a plant body. They are widely distributed throughout the plant body.

Functions :
(1) These cells mainly serve as packing tissue and constitute the bulk of the cortex, medullary rays, pith, xylem and phloem, fruit pulp and seed endosperm.
(2) It is storage tissue and store starch.
(3) Chloroplast containing parenchyma called chlorenchyma help in photosynthesis.
(4) Thick-walled parenchyma give mechanical support.
(5) Parenchyma containing air cavities called Arenchyma provide buoyancy to aquatic plants.

Collenchyma:
It is made up of parenchymatous cells which are elongated and are thick at the corner. It consists of living cells but is modified to provide mechanical support. There is extra deposition of cellulose at the corners of the cell.

This tissue is found in the leaf stalks and below the epidermis of the stem.

Functions :
It gives mechanical strength to the plant organs

Sclerenchyma :
The cells are dead with thick lignified cell wall. The cells are living when young but gradually loose protoplasm and die when fully formed. The cell wall is provided with cavities called pit.

It includes two types of cells fibre and sclereid or stone cells. Fibres are usually found in patches below the epidermis and endodermis, vascular bundle of leaf, stem and root.

Functions :
(1) Provide mechanical support.
(2) Stone cells provide rigidity to the plant.

Question 34. What are complex permanent tissues? Explain with a diagram the structure and functions of the xylem.
Answer:
Complex Permanent Tissue :
It is made up of more than one type of cell forming a mixed mass but working together as a unit. Two main types of complex tissue are the xylem and phloem.

Xylem :
Complex vascular tissue is concerned with the upward transport of water and minerals. It consists of four different types of cells, viz. Xylem fibres, xylem parenchyma, tracheids and vessels.

(1) Trachids are elongated tube-like, dead, single cells with perforation-lignified cell walls. Their end walls are tapered and overlap the adjacent tracheids. The cells have empty cavities called lumen. The walls have pit. Water can pass through the empty lumen.
(2) Vessels are long tube like structures formed by the SD fusion of several cells arranged end to end in a row. The long vessel helps in the transport of large amounts of water over long distancces.
(3) Xylem parenchyma – The cells are living, thin walled and abundant. These are mainly concerned with the short distance transport of substances and the storage of sugar, starch and lipid.

(4) Xylem fibre – Found mainly in woody plants. These do not conduct water and provide additional mechanical strength to the xylem.

Question 35. Name the different components of phloem. Write their functions.
Answer:
Phloem :
It possesses a tubular structure for the transport of food. The tube in the phloem is composed of living | PHLOEM – conducts be sounyard cells. It consists of four types of cells – phloem fibre, phloem-— parenchyma, Sieve tube and Companion cells.

(1) Sieve tube are long tube like structure, involved in transport of organic solute like sucrose throughtout the plants. These are formed by end to end fusion of sieve tube elements.
(2) Companion cells – Thin walled elongated cells, is associated with each Sieve tube. Cells are living filled densely with cytoplasm and large nucleus.
(3) Phloem parenchyma – Mainly storstoresod materials. These are living and often cylindrical.
(4) Phloem fibre – Dead cell of phloem tissue, similar to sclrenchyma fibres. It provides mechanical support. Sclereids are more common in older phloem.

Question 36. Name the major organs in the human body. State their location and functions.
Answer:
Major Organs of Humathe and Body and their Functions:
Different tissues are usually grouped to form a larger functional unit called orgAnswer: In animals, organs together form even larger functional units called systems (for example, a digestive system consisting of the stomach, intestine, liver, pancreas, etc.)

Position Functions Skin Situated all over the body inProtection human. As excrtory organ, excrete sweat. As sense organ for touch, pain and temperature. Stomach J – shaped muscular bag in the abdomen to- wards the left and Gastric gland secretes gastric just below the diaphragm. Juice which consltsts hydrochloric acid, mucous and enzymes. HCI convirts pepsinogen into pepsin which help in digestion of protein. Pancreas It is a mixed gland located Secret pancreatic Juice which posterior to stomach consists of enzymes trypsin, amylase, lipase. Trypsin converts protein into poty peptides, amylase acts on starch and convirt them into maltose.

Question 37. What is the importance of water in life ?
Answer:
Importance or Functions of water :-
ife can not exist without water. It has versatile functions in the body and life processes:
(1) It is a universal solvent for all chemical and physiological reactions.
(2) Water maintains electrolyte balance and acid base balance of body fluids.
(3) It allows body’s cells to grow, reproduce and survive.
(4) It is the major component of different body parts.
(5) It acts as an important medium for osmosis, diffusion, filtration, transport and other physical processes.
(6) It helps to deliver O₂, all over the body and transport of CO₂,
(7) In digestion, it keeps the mucosal membrane moist; makes food digestible; dilutes food for enzyme action; synthesis of digestive juice; medium for digestion; and absorption of digested food.
(8) It provides media um for all metabolic reactions.
(9) It lubricates joints.
(10) It regulates body temperature by sweating and respiration.
(11) It helps in detoxification and elimination of excretory products.
(12) It acts as a shock k absorber for the brain and spinal cord.
(13) It is needed by the brain to manufacture hormones and neurotransmitters.

Question 38. What is the role of acids, bases and salts in the body of living organisms?
Answer:
Acids :
A hydrogen ion is a single free proton released from a hydrogen atom. Molecules containing hydrogen atoms that can rélease hydrogen ions in solutions are referred to as acids, e.g. HCL (Hydrochloric acid) ionizes in water to form hydrogen ions (H⁺) and chloride ions (CI^–). Similarly, H₂CO₃, (Carbonic acid) ionizes in water to form H⁺ and HCO₃^–.

Some common inorganic acids in human body are—HCI in stomach, H₂CO₃ in blood, etc.

A base is an ion or a molecule that can accept W e.g. HCO₃ – is a base because it can combine with W to form H₂CO₃. Similarly, HPO₄^–, is a base because it can accept an H* to form

H₂PO₄^–.

In the human body, acid-base balance (buffer) is normally regulated by buffering agents— the respiratory system and the renal system. . .. Only six nonmetallic essential elements- carbon, hydrogen, nitrogen, oxygen,phosphorus and sulphur, make up most of the body weight (98%) of an organism. Various metals and nonmetals combine together to form different salts that are present in all living cells. :

Inorganic and organic salts of Ca, Mg, Na, K, and Fe, are very common in living cells.

Question 39. What is monosaccharide ? Write its structure, source and role in life processes.
Answer:
Monosaccharide :
They contain only one unit of simple sugar, e.g. Glucose, fructose, galactose, etc.

Basic Structural Features :
1. Colourless crystalline compounds, sweet in taste.
2. They undergo fermentation by yeast and other microorganisms.

Source :
Glucose (Dextrose) in grapes; Fructose (Laevulose)- fruit sugar which is present in almost all sweet fruits, honey; Galactose- it does not occur free in nature. In the body galactose is present as component of milk sugar (Lactose) which is formed of glucose and galactose.

Major Role in Life Processes :
1. Glycolysis – Glucose undergoes glycolysis to produce pyruvic acid in cell cytoplasm.
2. Storage — Excess glucose may be converted into starch in plants, glycogen in animals.
3. Maintenance of blood sugar — Normally 100 ml human blood contains 80-120 mg glucose.

Increase of this glucose level results into hyperglycemia (Diabetes mellitus) whereas decrease of glucose level is called hypoglycemia.

4. Synthesis of fats, pretend eins — By various metabolic reactions in life the r excess glucose may be converted to fatty acid, glycerol, amino acids, etc.

Question 40. Mention the basic features of amino acids. Discuss their role in life processes.
Answer:
Basic structural features :
1. Amino acid contains at least one central carbon (alpha) which is bound to a free amino group (—NH₂), a carboxyl group (— COOH), one hydrogen (— H) and a side chain (R) which is different in each amino acid. Besides, all other three positions are fixed.

2. Amino acids are colourless, crystalline substances, solublein water.

Role in life processes :
1. Structure and Function of protein :
Since protein is made of different amino acids, so structure and function of protein depend on its component amino acids.

2. First class protein :
The protein that contains all essential amino acids and are capable of growth and maintenance, e.g. Albumin, globulin proteins of egg, meat, fish, milk, etc. (Almost all animal proteins are first class proteins).

3. Second class protein :
The protein contains a few essential amino acids but not all and is not suitable for growth and maintenance, e.g. Zein of Maize (most of the plant proteins are second class protproteins

Question 41. What is fatty acid? Mention its features, types and source.

Answer: Fatty acid is the essential component of fat.

Basic structural features :
1. Fatty acid has a carboxyl group (COOH) attached to it.
2. It is insoluble in water but soluble in fat solvents like chloroform, ether, alcohol, etc.

Types:
1. Saturated fatty acid, e.g. stearic acid, palmitic acid etc. .
2. Unsaturated fatty acid, e.g. Oleic acid, Crotonic acid.
3. Essential fatty acid—that are needed for normal growth but are not synthesized in the body—so they are taken along with diet, e.g. Linoleic acid, Linolenic acid and Arachidonic acid.

Source :
Stearic acids in animal fat; palmitic acid in paim ojl, milk, meat; butyric acid in milk, butter etc; oleic acid in olive oil, sunflower oil, animal fat etc.

Question 42. What is the role of fatty acid in life processes ? Distinguish between amino acid and fatty acid.
Answer:
Role in life processes :
1. They help in normal growth of the body.
2. They are structural components of cells.
3. They are responsible for normal reproductive functions.
4. They are necessary for healthy skin.

Difference between Amino acid and Fatty acid :

Question 43. Mention the structural features of nucleotides.
Answer:
Basic structural features :
1. One nucleotide consists of pentose sugar (5 — c- sugar}, Nitrogenous base (N-Base) and phoshoric acid (H₃PO₄).
2. N—Base can be of — Purine [Adenine (A) and Guanine (G)] and Pyrimidine [Thymine (T), Cytosine (C) and Uracil (U)].
3. A, T, Gand are present in DNA whereas A, U, G and C are present in RNA.
4. Nucleotide consists of pentose sugar and nitrogenous base without H₃PO₄.

Question 44. What are complex carbohydrates ? Classify them.
Answer: Complex carbohydrates are oligosaccharides (disaccharides, trisaccharides, etc) and polysaccharides. They are formed of two or more monosaccharide units.

 

Simpler complex carbohydrates (Oligosaccharide) :
1. Disaccharides :
They are formed by the combination of two monosaccharide units with the elimination of one molecule water r.

e.g. Lactose (in milk) formed of glucose and galactose;

Sucrose (cane sugar) formis ed of glucose and fructose;

Maltose (malt sugar) form is the ed of glucose and glucose (i.e., two molecules of glucofose)

2. Trisaccharides :
They are formed by the union of three monosaccharide units. (Can you explain how many water molecules will be released in this structure ?)

e.g. Raffinose (found in beans, cabbage, broccoli etc) formed of glucose + fructose + galactose. :

3. Tetrasaccharides :
This is formed of four monosaccharide units. e.g. Stachyose (found in green beans, soya beans, etc.) formed of two molecules galactose + glucose + fructose.

More Complex Carbohydrates (Polysaccharide) :
Polysaccharides are polymers of large e number of monosaccharide units (monomer).

Polymer is the ‘garland’ whereas monomer is the ‘individual flower’ of the garland, e.g Glycogen is the polymer and each glucose unit is the monomer.

Basic Structural features :
1. They are commonly not seen.
2. Generally they are soluble in water (except cellulose).

Some common polysaccharides :
1. Starch — Polymer of glucose, produced by plants; insoluble in cold water; givegivee colour with iodine; tasteless.
2. Glycogen — Found in animals and fungi, known as ‘animal- starch’ soluble in water, gives a reddish colour with iodine.
3. Cellulose — Found in plants; insoluble in water; taken in the body along with vegetables; can not be digested in the human body.

Role in life processes :
1. Starch is the main constituent of food grains.
2. Glycogen is generally stored in the liver and muscle as a food reserve.
3. Cellulose forms ‘roughage’, stimulates peristalsis and helps in defaecation.
4. Carbohydrate (simple or complex) is the main source of energy when completely oxidised. One gram of ohydrate yields 4.0 Kcal energy.

Question 45. Mention the basic structural features of protein.
Answer:
Basic structural/ compositional features :
1. EsseThe essentialponent of protein is nitrogen.
2. The structural unit of protein is an amino acid.
3. Most of the proteins have a fishy smell.
4. When heated; protein coagulates
5. In acidic medium, protein is precipitated.

Question 46. What are enzymes? Mention their structural features and role in life processes.
Answer:
Enzyme :
Enzymes are biological catacatalystsotein in nature, produced by the
living cells, accelerate various biochemical reactions, but the selves remain undestroyed after the action.

Basic compositional features:
1. Nature — Almost all enzymes are proteins.
2. Structure — Like all other proteins, the enzyme is also formed of several amino acids.
3. Active site — We ingest food through our mouth, so mount the h is the ‘active site’ for ingestion. Similarly enzyme also performs its function by the ‘active site’ at a higher rate.
4. Specificity — Each enzyme acts on a specific substrate, e.g. Protease acts only on protein; lipase acts only on lipids, etc.
5. Catalytic property — Since enzymes act as biocatalysts, they are not destroyed at the end of the reaction.
6. Medium (pH) — Each enzyme acts in a definite medium, e.g. ptyalin in neutral = medium, pepsin in acidic medium, trypsin in alkaline medium and so on.
7. Temperature — Enzyme shows maximum activity in optimum temperature (GONG 40°C). At very high temptemperaturesove 40°C) enzyenzymes get damaged
(denaturation).
8. Action — Enzyme action is reversible and may be inhibited by a suitable inhibitor.

Role in life processes :
1. EnzyEnzymeselerate different biochemical reacreactions They are essential for any metabolic reaction in living organisms.
3. They play a very significant role in digestion.

Question 47. Discuss the role of lipids in life processes.
Answer:
Role in life processes:
1. Calorific value :
Lipid provides a food with high calorific value. One gram of lipid produces about 9.3 Kcal energy.+

2. Storage :
Lipid acts as reserve food material because it can be easily stored in the body for future use.

3. Reaction :
The storage (depot) fat protects the vital organs, skin, etc, and also acts as cushion and packing tissues.

4. Heat insulations :
Lipid acts as insulin later. Thus subesubcutaneous helps to regulate body temperature (thermoregulation).

5. Solvents :
Lipid is a good solvent for fat-soluble fat-solubleamins like Vit. Ay DP ERK

6. Hormone synthesis :
From cholesterol, all steroid hormones are synthesized in animals.

Question 48. Discuss the structural features of DNA and RNA.
Answer: DNA (Deoxyribose Nucleic Acid)

It is usually double-stranded or double-helical.

Two complementary chains are named as  (alpha) and  (Beta)

Two chains are antiparallel and interlinked by H-bonds. The structural unit of DNA is called deoxyribonucleotide which consists of pentose (deoxy-ribose) sugar, H₃PO₄ and N-Base.

N-Base can be of two types — purine and pyrimidine.

Purine of DNA is again of two types — Adenine (A) and Guanine (G), whereas pyrimidine is again of two types — Thymine (1) and Cytosine (C)

RNA (Ribo Nucleic Acid) :
1. It is generally single-stranded or single-helical.
2. The structural unit of RNA is ribonucleotide which consists of pentose sugar (ribose), H3PO4 and N-Base.
3. N-Base can be of two types — Purine and Pyrimidine.
4. Purine in RNA is of two types — Adenine (A) and Guanine (G) whereas pyrimidine is again of two types-Uracil (U) and Cytosine (C).

Question 49. Distinguish between DNA and RNA.
Answer:
Difference between DNA and RNA:

Question 50. Discuss the role of DNA and RNA in life processes.

Answer:
DNA:
(1) It contains genes and is responsible for the range of characteristics from parents to off offspring) It is responsible for all characteristics of an organism.
(3) Tt controls cell division where a mother cell divides itself to produce two daughter cells.

RNA:
(1) In plant viruses like TMV (Tobacco Mosaic Virus) and some animal viruses like Influenza virus, HIV, etc. RNA contains genes- so RNA is the genetic material in them.
(2) MRNA (Messenger RNA) carries information from DNA and helps in protein synthesis.
(3) tRNA (Transfer RNA) collects amino acids from cell the cytoplasm protein synthesis.
(4) rRNA (Ribosomal RNA) is the structural component of riboribosomes that helps in protein synthesis.

Question 51. Discuss the role of ATP as the energy currency of cell cells:
Role of ATP as Energy Currency of a cell :
ATP (Adenosine Tri Phosphate) is the primary molecule for storing and transferring energy in cells. It is often referred to as “energy currency of the cell” and may be compared to storing money (ATP) is a bank (cell). In any energy-related chemical reaction of the cell, ATP is either produced or consumed. For example, during photosynthesis, ATP is synthesized by photophosphorylation) using solar energy, whereas during respiration, ATP is synthesized through glycolysis, the Krebs cycle, and ETCC. The production of ATP in ETC is known as oxidative phosphorylation.

ATP is a nucleotide consisting of a N-Base [Adenine (A)], attached to a ribose pentose sugar (s-c-sugar), which is attached to three phosphate groups, that are linked to one another by two high-energy bonds.

ATP: Adenosine – P ~ P ~ P (N- Base)

The symbol ~ designates a high energy. So; in 1 ATP, there are 2 high energy bonds. When these high-energy bonds are broken, energy is released, which is utilized for any biochemical reaction of the cell or body.

ATP = ADP + Pi + energy
ATP = AMP + PPi + energy

Question 52. What are the characteristics of vitamins ?
Answer:
General characteristics of vitamins :
1. Vitamins are obtained from plant products and animal products.
2 . The daily requirement of vitamins is very low.
3. A small amount of fat-soluble vitamins may be stored in the liver and vitamin C in the adrenal cortex.
4. Vitamins are destroyed after reaction hence they must be supplied to the body regularly.
5. Some of the vitamins are heat stable (e.g. vitamin A, D, E, K, B, etc) but some of the vitamins are heat labile (e.g. vitamin B1, B3, vitamin C, etc).

Question 53. What is a micra tubule? Mention its structure and functions:
(1) Microtubule:
In the cytoplasm of eukaryotic cells are numerous non-membranous hollow cylinders known as micrmicrotubules) Structure :

Microtubules have variable length. They are formed of a special type
of protein called tubulin. Each tubulin consists of two sub-units (dimer) — @ and f.

(3) Functions :
(1) They from a supporting framework or cytoskeleton and give
shape to the cell.
(2) Microtubules form spindle during mitomitotic/meiotic division. (3)They form cilia and flagella that help in movement.

Question 54. Distinguish between — (a) Parenchyma and Collenchyma, and (b) Collenchyma and Sclerenchyma.
Answer:
Difference between Parenchyma and Collenchyma :

Difference between Collenchyma and Sclerenchyma:

Question 55. Distinguish between xylem and phloem.
Answer:
Difference between Xylem and Phloem:

Question 56. Make a comparison of parenchyma, Collenchyma and Sclerenchyma.

Answer:

Question 57. What is stratified epithelium? Classify it.
Answer: Stratified epithelium or stratified epithelial tissue is composed of many layers of cells. Depending on the shape of the constituting cells and structural arrangements this variety of tissue is sub-divided into the following types
(1) Stratified squamous cornified-found in the skin and helps to protect from injury;
(2) Stratified squamous non-cornified- found in the cornea, mouth, pharynx, etc. and helps to afford mechanical protection;
(3) Stratified cubical- found in the pharynx, epiglottis, etc. (iv) Stratified columnar ciliated- found in the oft palate, some parts of larythe nx, etc.

 

• Chapter 1 Life and Its Diversity
• Chapter 3 Physiological Processes of Life
• Chapter 4 Biology and Human Welfare
• Chapter 5 Environment and its Resources