NEET Class 9 Biology

Improvement In Food Resources Long Answer Questions

Question 1. What does the Variety Improvement of crops aim at?
Answer: The aim of Variety Improvement of crops is for:

1. Higher Yield: To develop high-yielding varieties so as to increase the productivity of crop per acre.
2. Improved Quality: With changes in lifestyles of people, there is an increased demand for better quality. Quality considerations vary from crop to crop like baking quality in wheat, protein quality in pulses, oil quality in oil crops and preserving quality of fruit and vegetables.
3. Biotic and Abiotic Resistance: Crop yields decrease due to biotic and abiotic stresses under different situations. Varieties resistant to these stresses are needed to improve crop production.
4. Change in Maturity Duration: A shorter duration of the crop from sowing to harvesting makes the variety more economical.
5. Wider Adaptability: Varieties capable of growing successfully under different environmental conditions to help in stabilising the crop production at places having different environment.
6. Desirable Agronomic Characteristics: Developing varieties of desired agronomic characters help in giving higher productivity

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Question 2. Describe the objectives of plant breeding.
Answer: The various objectives of plant breeding are listed below :

1. High yield: It is the primary concern of the plant breeder to produce a crop variety having increased productivity per acre. It is achieved by developing and selecting more effiient genotype.

2. Improved quality : In addition to quantity, it is necessary for the breeder to consider the quality of the Plant produce. For example, sweet, juicy and seedless oranges are preferred over a large number of sour, pithy ones.

3. Biotic and abiotic resistance. Under natural conditions, the crop plants are prone to certain biotic (diseases caused by bacteria, fungi, nematodes, etc. or damage caused by insects) and abiotic (drought, salinity, water lodging, heat, cold and frost) stresses which cause a great loss of production.

4. Change in maturity duration: Production of a crop can be increased many times by reducing the time duration from sowing to harvesting. It saves time, labour, irrigation, fertilizers and money.

5. Wider adaptability: An ability to withstand the extremes of moisture, drought, temperature and other conditions, by the cultivated plants, is another desirable trait by the breeders.

6. Development of novel varieties: Developing a new variety with increased food production is not enough. The breeder is always on the lookout for novel varieties which attract the consumer. Seedless tomatoes, oranges, lemons, stoneless lums, and peaches are some of the products of the breeder’s honest efforts which have captured the market.

Question 3. State one indicator each for infestation by insects and rodents in stored food grains. Describe one method each for controlling the population of insects and rodents.
Answer: The presence of cocoons, webs and weevilled grain indicates the infestation by insects. Presence of excreta and holes in the bags indicates the infestation by rats.

• Method of controlling insects in storage by fumigation: Fumigation is the most effective method for controlling the insects without affecting the grains, example. , ethylene dibromide.
• Depending on the quantity of grains to be fumigated, a certain number of EDB ampules wrapped in cloth are inserted a little below the surface of the grain and broken gently. The structure is left air-tight and undisturbed for a week. Toxic fumes diffuse and kill the insects.

Method of controlling rodents: Using single or multiple doses of rodenticide is an effective method of killing rodents. The baits can be prepared by mixing flur of cereals with jaggery or sugar with edible oil and rodenticide in right proportion, .example zinc phosphide.

Question 4. What are manures? Give its classifiation.
Answer: Manures contain large quantities of organic matter and supplies small quantities of nutrients to the soil. It is prepared naturally by the decomposition of animal waste, excreta and plant waste.

• It helps in the soil enrichment with nutrients.
• It helps in improving the soil structure.
• It helps in increasing the water holding capacity in sandy soils.
• In clayey soils it helps in the water drainage and prevent water logging. Manure is classified based on the kind of biological material used to make it.

1. Compost
2. Vermicompost
3. Green manure.

Compost: The farm waste and livestock excreta, along with vegetable waste. Sewage wastes weeds, straws, etc. are allowed to decompose in a pit is called compost. The compost is rich in nutrients.

Vermi Compost: When the above-given matter is allowed to decompose in the pit along with same earthworms, the decomposition speeds up and is called vermicomposting.

Green Manure: The same plants like sun-hemp or guar are grown and then mulched by plowing them into the soil. This is done before the sowing of crop seeds into the field. These green plants present in the soil acts as green manure which enriches the soil in nitrogen and phosphorus.

Question 5. What are the different patterns of cropping?
Answer:

Different ways/patterns/systems of growing crops are:

1. Mixed cropping
2. Inter-cropping
3. Crop-Rotation.

• Mixed Cropping: It is a method in which two or more crops grow simultaneously on the same piece of land. Example: Wheat + grain, Wheat + mustard, or groundnut + sunflower. This helps in the reduction of risk factors and provides insurance against the failure of one of the crops.
• Inter-Cropping: It is growing two or more crops simultaneously on the same field in a definite pattern. A few rows of one crop alternate with a few rows of a second crop Example: soybean + maize or bajra + labia
• Crop-rotation: The growing of different crops on a piece of land in a pre¬planned succession is known as crop-rotation. The availability of moisture and irrigation facility decides the choice of crop to be cultivated after one harvest.

Question 6. Explain different types of fisheries.
Answer: The different types of fisheries are marine fisheries, and Inland fisheries, capture fishing, culture fishing, mariculture, aquaculture.

Marine fisheries: Marine fish are caught using fishing nets. Large school offices are located by satellites. Some are farmed in seawater.

Mariculture: Marine fish are cultured in seawater this culture of fisheries is called mariculture.

Inland fisheries: The fisheries are done in freshwater, resources like canals, ponds, reservoirs, and rivers.

Capture fishing: It is done in seawater, estuaries, and lagoons.

Aquaculture: The culture of fish done in different water bodies is called aquaculture

Question 7. What are the various methods of irrigation in India?
Answer: Most of the agriculture in India is rain-fed, and several different kinds of irrigation systems are adopted to supply water to agricultural lands. The resources are wells, canals, rivers, and tanks.

Wells: Dug wells-water is collected from bearing strata.

Tubewells: Can tap water from deeper strata.

• Canals: Most extensive irrigation system. Canals receive water from reservoirs or rivers. The main canal is divided into branch canals having further distributories to irrigate fields.
• River lift system: Water is directly drawn from the river for supplementing irrigation in areas close to
  rivers.
• Tanks: These are small storage reservoirs, which intercept and store the run-off of smaller catchment
  areas

8. Large amounts of food grains get spoiled every year in India due to improper storage of food grains. How can this be avoided?
Answer: Food grains get spoiled by insects, fungi, rodents, bacteria, moisture, and temperature in the place of storage. Storage losses can be minimized by following preventive and control measures.

1. The seeds/grains that are to be stored should be dry, with no moisture in them.
2. The grains should be cleaned.
3. The grains should be fumigated using chemicals that kill the pest.
4. The storage houses should be waterproof.
5. The grains should be stored in sealed gunny bags or metal containers.
6. The bags should be stacked in order in a pile for proper fumigation and should be kept few centimetres away from the wall.
7. The ventilators if any should be closed tightly, to avoid birds visiting the storage house and destroy
   the grains.
8. The walls and the floor should be water-proof with no holes in it, to avoid rodents and pests.

The Fundamental Unit of Life Long Answer Questions

Directions: Give answer in four to fie sentences.

Question 1. How is the structure of a plasma membrane related to its function?
Answer:

1. The plasma membrane has three major functions:

1. It selectively isolates the cytoplasm from the external environment,
2. It regulates the flw of materials into and out of the cell, and
3. It communicates with other cells.

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The membrane consists of a bilayer of phospholipids in which a variety of proteins are embedded. There are three major categories of membrane proteins:

“the fundamental unit of life “

1. Transport proteins, which regulate the movement of most water-soluble substances through the membrane;
2. Receptor proteins, which bind molecules in the external environment, triggering changes in the metabolism of the cell; and
3. Recognition proteins, which serve as identifiation tags and attachment sites.

Question 2. What are the principles of cell theory? Describe it.
Answer:

The principles of the cell theory are:

1. Every living organism is made up of one or more cells and products of cells.

2. The smallest living organisms are single cells, and cells are the functional units of multicellular organisms.

3. All cells arise from preexisting cells.

Cells are limited in size because they must exchange materials with their surroundings by diffusion. Because diffusion is relatively slow, the interior of the cell must never be too far from the plasma membrane, and the plasma membrane must have a large surface area through which materials can diffuse relative to the volume of its cytoplasm. All cells are either prokaryotic or eukaryotic. Prokaryotic cells, or bacteria, are small and relatively simple in structure. More complex eukaryotic cells make up all other forms of life like protists, fungi, plants and animals.

Question 3. Draw a neat labelled diagram of plant cell and label its parts.
Answer:

Question 4. Draw a neat labelled diagram of animal cell.
Answer:

Question 5. Briefl explain the structure ofchromosomes.
Answer:

Chromosomes are thread-like structures usually present in the nucleus and become visible only during cell division. These contain hereditary information of the cell. DNA (deoxyribonucleic acid), and Proteins. DNA is the most important component of a chromosome. These look like rods during the metaphase stage of the cell division. Each chromosome consists of two arms called chromatids which lie side-by-side along their length. The two chromatids of a chromosome are attached at a point called primary constriction of centromere. One or both the arms of a chromosome may have secondary constrictions. The smaller part of chromosome separated by secondary constriction is called satellite. Chromosomes in which satellite is present are called SAT-chromosomes.

“fundamental unit of life “

Question 6. Describe various components of a nucleus in a eukaryotic cell.
Answer:

Nucleus envelope: It is bounded by two nuclear membranes, together referred to as nuclear envelope. The two nuclear membranes are designated as outer membrane and inner membrane.

Nuclear Sap: It is aclear, non-staining, flidmaterial present in the nucleus, also termed nucleoplasm. It contains raw materials, enzymes, proteins and metal ions for the synthesis of nucleic acids (DNA and RNAs) and ribosomal sub-units.

“class 9 science chapter 5 intext questions “

Chromatin material: It occurs in a non-dividing nucleus as fie fiaments termed as chromatin fires. These fires lie criss cross and give the appearance of a diffuse network. Chromatin fires help in cell division due to condensation of chromatin material. These are made up of DNA and proteins. The DNA possesses all the necessary information for the cell to function, grow and divide properly. The specifi segments of DNA are termed genes. These are the hereditary units.

Nucleus: There is/are one or more rounded bodies called nucleoli (singular: nucleolus) are present in the nucleoplasm.

Nuclear Matrix: It is a networkoffie, criss crossing, protein-containing firils which are joined to the nuclear envelope by their ends. These maintain the shape of nucleus.

Question 7. Explain structure and functions of plastids.
Answer:

The chloroplasts of higher plants are usually spherical, ovoid, discoidal or lens shaped. Each chloroplast is a vesicle bounded by double membrane envelope and filed with a flid matrix like the mitochondrion. The outer membrane is smooth and freely permeable to small molecules. Inner membrane is, however, selectively permeable. It has carrier proteins that control the passage of molecules. It is greatly infolded but the infolds become free in the mature chloroplast to lie as lamellae in the matrix.

Plastids perform many important functions:

1. The chloroplasts trap the radiant energy of sunlight and transform it into the chemical energy of carbohydrates using water and CO₂ (carbon dioxide). The process is called photosynthesis.

2. The chromoplasts impart various colours to flwers to attract insects for pollination and to the fruits for alluring certain animals for seed dispersal.

3. Leucoplasts store food in the form of starch (carbohydrates), fats and proteins.

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Question 8.

1. What is endoplasmic reticulum?
Answer:

The ER is an extensive network of intracellular membrane-bound tubes and vesicles that occupies most of the cytoplasm in almost all eukaryotic cells.

2. Describe its structure.
Answer:

The membranes of endoplasmic reticulum system are lipoproteinic in nature similar in structure to the plasma membrane. The ER is more prominent in young and dividing cells as compared to older cells. It is absent in prokaryotic cells.

3. Name the two types of endoplasmic reticulum.
Answer:

The ER is of two types:

1. Rough endoplasmic reticulum (RER)
2. Smooth endoplasmic reticulum (SER)

4. What crucial role does it play in the liver cells of vertebrates?
Answer:

The SER brings about detoxifiation in the liver, i.e., it converts harmful materials (drugs, insecticides, pollutants and poisons) into harmless substances for excretion by the cell.

5. What is membrane biogenesis?
Answer:

The endoplasmic reticulum helps in the manufacture of fat molecules or lipids, which are important for the cell function. These proteins and lipids helps in the building of the cell-membrane. This process is known as membrane biogenesis.

Question 9. Explain the following:
Answer:

Active transport

This type of transport across plasma membrane is rapid and requires the use of energy in the form of ATP. It usually occurs against the concentration gradient and involves the use of carrier proteins. Glucose, amino acids and some ions (e.g., Na+ and K+) pass through the plasma membrane by active transport or contransport.

Exocytosis

Exocytosis is the process that involves fusion of membrane of the exocytotic vesicle with the plasma membrane to extrude its contents to the surrounding medium.

Phagocytosis.

Phagocytosis is the intake of solid particles by a cell through cell membrane. It is also called cell eating. Phagocytosis is the major feeding method in many unicellular organisms (e.g. , Amoeba) and simple metazoa (e.g., sponges). It is also the means by which leucocytes of blood engulf uninvited microbes (e.g., viruses, bacteria), cellular debris etc. in the blood. Such cells are called phagocytes.

Why Do We Fall Ill Long Answer Questions

Directions: Give answer in four to fie sentences.

Question 1. How does the body defend against invasion?
Answer:

The human body has three lines of defense against invasion by microbes:

The Barriers Of Skin And Mucous Membranes

Nonspecific Internal Defenses, Including Phagocytosis, Killing By Natural Killer Cells, Inflammation, And Fever; And

The immune response. The skin physically blocks the entry of microbes into the body. The mucous membranes of the respiratory and digestive tracts secrete antibiotic substances, antibodies, and mucus that traps microbes. If microbes do enter the body, white blood cells travel to the site of entry and engulf the invading cells. Natural killer cells secrete proteins that kill infected or cancerous cells. Injuries stimulate the inflmmatory response, in which chemicals are released that attract phagocytic white blood cells, increase blood flw, and make capillaries leaky. Later, blood clots wall off the injury site. Fever is caused by endogenous pyrogens, chemicals released by white blood cells in response to infection. High temperatures inhibit bacterial growth and accelerate the immune response.

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Question 2. Write short note on bacterial disease.
Answer:

Common bacterial diseases discussed below are diarrhoea, typhoid, and tuberculosis etc. Diarrhoeal diseases are a group of intestinal infections, including food poisoning. The causative agents are mainly bacteria such as Staphylococcus, Clostridium, Escherichia coli, Shigella, Salmonella etc. A protozoan Giardia and some viruses also act as causative agents. Infections of Diarrhoea spread through generally contaminated food, water, drinks etc. , and occasional contamination through fingers, clothes, bedsheets, utensils etc.

Symptoms:

• Common symptoms of diarrhoea infections include:
• Abnormally frequent discharge of semisolid or fluid fecal matter with or without blood mucus (i.e., diarrhoea).
• Diminished appetite.
• Abdominal cramps, nausea, and vomiting lead to dehydration.

Uses:

• The use of antidiarrhoeal antibiotics can treat the disease. Saline drip may be given intravenously to maintain flid and electrolytes in the body. Alternatively, oral rehydration solution (ORS) may be given to the patient periodically. Isabgol (husk of Plantago ovata seeds) should be given with curd to the patient to provide relief.
• Typhoid is a common bacterial disease caused by a rod-like bacterium, Salmonella typhi.
• Tuberculosis is caused by a bacterium, Mycobacterium tuberculosis. The bacterium commonly affects the lungs, where small tubercles are formed. It may also attack brain, intestine, eyes etc. The bacterium damages tissues and releases a toxin called tuberculin which produces the disease.
• Malaria is a very serious disease of the tropical and sub-tropical regions especially in Africa and Asia.
• Malaria is caused by the toxins produced in the human body by the malarial parasite Plasmodium.

Question 3. List various causes of diseases.
Answer: The means of spread or cause of communicable diseases are different for different pathogens.

1. The disease-causing microorganisms (pathogens) are transmitted from infected person to healthy person(s) directly by physical contact with infected person. The pathogens of diseases like chicken pox, smallpox, ringworm etc. are spread through physical contact with an infected person or through articles of use.
2. Few infectious diseases such as syphilis, gonorrhea (both caused by bacteria), and AIDS (caused by a virus) are transmitted by sexual contact from one partner to the other.
3. Many pathogens can enter the human body from the soil through injuries (e.g. tetanus).
4. Communicable diseases can also spread through the animal bites. For example, the rabies virus enters the human body by the bite of rabid dog or monkey to cause rabies.
5. Indirect transmissions involve the spread of pathogens of some diseases through some intermediate agents. Indirect transmission occurs through air.
6. The infected person throws out little droplets while sneezing, coughing or spitting. Someone standing close by can breathe in these droplets and, thus, microbes get a chance to start a new infection in this person.
7. Many animals living with us carry the infecting agents from an infected person to another potential host. These animals act as intermediaries and are termed vectors. The vectors are, therefore, the carriers of the disease-causing pathogens. The most common vectors are the insects.

Question 4. Write about various preventive measures to cure infectious diseases.
Answer:

While treating an infectious disease, the following three limitations are normally confronted:

1. Once a person suffers from a disease, his body functions are impaired and may never recover completely.
2. As treatment takes time, the patient is confined to bed for some time.
3. The infected person serves as a potential source of spread of this infectious disease to other persons in the community.
4. Keeping in view these limitations, the prevention of diseases is considered far better than their cure. Preventing measures are precautionary steps taken to check the transmission of infectious diseases.

Question 5. Write an account about acute and chronic diseases.
Answer:

Acute diseases: These diseases last for only short periods of time and are severe. Acute diseases do not cause long-term bad effects on our health. Examples of acute diseases are colds, coughs, typhoid, cholera, etc.

Chronic diseases: These diseases last for a long time, even as much as a lifetime. Chronic diseases have drastic long-term effects on patient’s health. Examples of chronic diseases are diabetes, tuberculosis, elephantiasis, cardiovascular diseases, arthritis, cancer, etc. Elephantiasis is very common in some parts of India.

Question 6. What are the basic conditions for good health?
Answer:

The basic conditions for good health are:

1. A properly balanced and nutritious diet
2. Personal hygiene
3. Clean surroundings and a clean environment
4. Regular rest
5. Proper rest
6. Good economic status

Question 7. State the mode of transmission for the following diseases. Malaria, AIDS, Jaundice, Typhoid, Cholera, Rabies, Tuberculosis, Diarrhoea, Hepatitis. Influenza.
Answer:

Question 8. Name the micro-organisms that cause infectious disease and name a few diseases caused by each microorganism.
Answer:

Natural Resources Long Answer Questions

Directions: Give an answer in four to five sentences.

Question 1. How is energy flux related to carbon oxidation and reduction reactions?
Answer:

Most energy transformations in nature are associated with biochemical oxidation and reduction of carbon, oxygen, nitrogen, phosphorus, and sulfur. The oxidation of the carbon in carbohydrates in respiration releases energy whereas the reduction of carbon in photosynthesis requires the energy input from the sun. The gain of energy in photosynthesis and the subsequent use of that energy in respiration is the fundamental energy flow of nature

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Question 2. How might the oceans serve as a sink for carbon dioxide?
Answer: The ocean’s ability to dissolve carbon dioxide is related in part to the dynamics of biogenic carbonates in the water. When carbon dioxide dissolves in water, it forms carbonic acid), which readily dissociates into bicarbonate and carbonate ions.

When carbon dioxide is removed from ocean surface waters by photosynthesis, the equilibrium between carbon dioxide, bicarbonate, and carbonate changes, resulting in the formation and precipitation of calcium carbonate. This creates a sink for carbon dioxide

Question 3. Explain the process of soil formation.
Answer:

Soil is formed through two processes weathering and humifiation.

Weathering: It is the pulverisation of rocks of breaking of rocks into fid particles. There are three types of weathering physical chemical and biological. Sun, water, wind and living organisms perform them.

1. Sun. It causes the expansion of rocks by heating. Cooling causes their contraction at different parts differently. Uneven expansion and contraction produce cracks leading to fragmentation or rocks.
   1. Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
   2. Frost Action is caused by water seeping in cracks which swell up and exert great pressure if it freezes due to low temperature and undergoes fragmentation.
2. Dust and fie sand carried by wind cause abrasion of the rock surface when the wind strikes the same.
3. Lichens secrete chemicals to dissolve minerals
4. From the rock surface and produces crevices where dust collects. Mosses grow there and cause deepening of crevices. Roots of short-lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.
   • Partially decomposed organic matter or humus mixes with weathered rock particles to form soil called humiliation. Humus helps in the formation of soil crumbs which are essential for maintaining proper hydration and aeration of soil.

The different causes of water pollution are :

Question 4. What are the causes of water pollution? Discuss how you can contribute to reducing water pollution.
Answer:

1. Domestic sewage and municipal water released directly into waterbodies
2. Untreated industrial waste released into waterbodies.
3. Fertilisers, detergents and biocides reach the waterbodies through drains and rain water.
4. Oil leakage from oil pipelines or from oil tankers into sea.
5. Waste from atomic reactors containing radioactive isotopes is thrown into rivers and seas.
6. Hot water from factories and power plants is released into waterbodies before cooling (thermal pollution.)
7. Eutrophication is caused due to decomposition of organic wastes thrown into waterbodies.

The following measures can be taken to check water pollution :

1. Treatment of sewage water before being discharged into water resources.
2. Treatment of industrial effluents before being discharged into the river.
3. Preventing toxic substances and radioactive substances from being thrown in waterbodies.
4. Hot water from power plants and factories should be discharged into waterbodies after cooling.
5. Lesser use of fertilisers and biocides.
6. Washing of cloth should be avoided near water-bodies.
7. Dead animals and decaying plants should not be thrown into water bodies.
8. The government should pass laws to prevent water pollution

Question 5. Carbon dioxide is necessary for plants. Why do we consider it as a pollutant?
Answer:

• It is true that CO₂ is necessary for plants as they need it to synthesise carbohydrates during photosynthesis, but an excessive amount of CO₂ (more than normal concentration) in the atmosphere becomes harmful to living organisms and hence is considered as pollutant.
• The CO₂ is formed inside the body of living organisms as a result of cellular oxidative metabolism. It diffuses out of the body through diffusion. Its excess amount inside the body is harmful.
• Moreover, an excessive amount of CO₂ is causing global warming (greenhouse effect) by forming an envelope around the earth which prevents heat from the earth’s surface from escaping into the atmosphere.

Question 6. How do fossil fuels cause air pollution?
Answer:

• Due to the burning of fossil fuels, like coal and petroleum, oxides of sulphur and nitrogen (SO₂, SO₃, NO₂) are released in the air and act as pollutants and cause respiratory disorders like asthma, bronchitis, pneumonia, lung cancer, etc.
• When the amount of SO₂ and NO₂ increases in the atmosphere, they combine with rainwater to form sulphuric acid ( H₂SO₄) and nitric acid ( HNO₃). When this acid water falls on the earth as rain, it is termed acid rain.
• Acid rain not only decreases soil fertility but affects the animal and human life in several ways.
• Suspended particles in the atmosphere may increase which reduces the visibility. Incomplete combustion of fossil fuel causes the release of CO in the air which is called carbon monoxide poisoning

Question 7. Explain the water cycle with a diagram.
Answer:

1. Water from different water bodies gets evaporated due to the sun’s heat. Plants also loose water during transpiration.
2. The hot air rises up with this water vapour.
3. Water vapour condenses to form big water droplets and clouds.
4. Rain water falls from clouds.
5. The rain water re-enters the water bodies. This process in which water evaporates falls on the land as rain and later flows back into the sea, rivers are known as the water cycle.

Question 8. Give the existence of carbon.
Answer:

1. Carbon exists in two different forms in nature free and combined form.
2. Free form: It occurs in the elemental form as diamond and graphite.
3. Combined form: It occurs as carbon-dioxide, carbonates and hydrogen carbonate salts in various minerals, it is also present in proteins, carbohydrates fats, nucleic acids and vitamins.

Carbon cycle:

1. Carbon dioxide present in nature is used by plants during photosynthesis to form glucose and carbohydrates.
2. CO₂ dissolves in water to form carbonates which form limestone.
3. Plants contain carbon in the form of glucose, a carbohydrate that is eaten by other animals. Plants and animals can form animals petroleum if submerged under the earth and plants form coal. But they get decomposed after dying they releaseCO₂back to the atmosphere by decomposition (dead) and respiration (living)

Question 9. Explain the biosphere.
Answer:

1. Biosphere: It consists of the sphere where life exists. Life can exist if all the spheres given below exist.
2. Lithosphere: The crust of the earth also called as land which forms the upper layer of the earth i.e.-soil. The soil provides all the nutrients for all organisms.
3. Hydrosphere: Water available in various forms on the Earth is called hydrosphere. Water exists in solid ice, liquid water and gaseous water vapour forms. It is used by all life forms for their survival.

Water helps in the transportation of nutrients, dissolves nutrients and minerals in it, and makes it available for plants.

Atmosphere: The atmosphere consists of air with different gases present in it like O₂, N₂, CO₂ other gases. Ozone present in the stratosphere helps the various gases present in the atmosphere and is useful for combustion (O₂) respiration (O₂), Photosynthesis (O₂) etc

Question 10. Explain the nitrogen cycle in nature and defie all the terms involved in it.
Answer:

Terms involved in the nitrogen cycle are

1. Nitrogen fixation: Plants cannot use free nitrogen present in the air. This nitrogen molecule is converted into nitrates and nitrites which can be taken up and used to make the required molecule. This is called nitrogen fixation which can be done by the bacteria that live in the root nodules of leguminous plants.
   • By physical processes during lightning, high temperatures and pressures are created in the air which converts nitrogen into oxides of nitrogen that dissolve in water and come down along with rain. This is also called nitrification.
2. Ammonifiation: The nitrogen compounds formed are taken by plants to form proteins which are further converted into ammonia.
3. Denitrification:  The nitrates and nitrites of nitrogen are acted upon by another group of microbes example, Pseudomonas bacteria, which convert these compounds into free nitrogen gas.

Nitrogen cycle :

1. Free nitrogen from the atmosphere is converted into nitrates by bacteria or by lightning.
2. Nitrates mix with soil, and are absorbed by the plants to make proteins.
3. The proteins in plants and animals are converted into amino acids and ammonia.
4. Ammonia is converted into nitrates and then these nitrates and nitrites present in soil are acted upon by another group of bacterias called denitrifying bacteria.

The process is called denitrification, nitrates are converted into free nitrogen and are released back into the atmosphere.

Question 11. What is the greenhouse effect? Why it is named so?
Answer:

In cold countries where the temperature is low and vegetation does not grow, heat is trapped by glass which allows the heat radiations to enter into the glass but cannot escape out from the glass. These hases are warm where plants grow and are called green-haves.

Greenhouse effects: In nature, there are certain gases in the atmosphere like CO₂, and methane, which allow the sun’s heat to enter the atmosphere but after reflection, these radiations cannot escape out of the atmosphere due to these gases. They help in increasing the temperature and hence called green house effect

Question 12. Explain the following :

1. Eutrophication
2. Biomagnification

Answer:

1. Eutrophication is the process in which excessive growth of algae (commonly called algal bloom) occurs as a result of extra loading of nutrients in the water body. In fact, the presence of sewage and fertilizers (nitrates and phosphates) in polluted water provides a lot of nutrients to the algae (phytoplanktons, etc.) present in the water body. As a result, excessive growth of algae occurs which is termed algal bloom.

• The algae subsequently die and aerobic decomposers become active. They consume rapidly the dissolved oxygen of the water and decompose these dead algae. In the absence of dissolved oxygen, all the aquatic life (including fish) in the water body dies. Thus, eutrophication deprives us of one of our sources of food.

2. The phenomenon of an increase in the concentration of harmful non-biodegradable chemical substances in the body of living organisms at each trophic level of the food chain is called biomagnification or biological magnification. Regular discharge of industrial wastes carrying heavy metals in water bodies has led to the biomagnification of heavy metals such as mercury, cadmium etc. leading to deadly diseases in fish-eating people

Question 13. Explain the ozone layer, its depletion and the effects of ozone depletion.
Answer:

• The ozone layer, comprising a high concentration of ozone about 18-50 km above in the atmosphere, is commonly called the ozone blanket.
• It is being depleted by air pollutants. Chlorofluorocarbons (CFCs) are synthetic harmful chemicals that are widely used in refrigerators and air conditioners as coolants; in fie extinguishers, in aerosol sprayers, and as propellants.
• These chlorofluorocarbons are air pollutants and are mainly responsible for the depletion of the ozone layer in the atmosphere. When these are released in the air, these harmful chemicals produce ‘active chlorine’ (Cl and CIO radicals) and fluorine in the presence of UV radiation.
• These radicals, through a chain reaction, then destroy the ozone by converting it into oxygen. Due to this, the ozone layer in the upper atmosphere (i.e., stratosphere) becomes thinner. A single chlorine atom can destroy one lakh ozone molecules. Choloroflorocarbons are, therefore, termed major Ozone depleting substances (ODS).
• Other ozone-depleting substances are nitrogen oxides and hydrocarbons. The thinning of the ozone layer allows more ultra violet (UV) radiation to pass through it which then strikes the Earth.

These cause the following harmful effects on man, animals and plants

1. Skin cancer.
2. Damage to the eyes; also increases the incidence of cataract disease in eyes.
3. Damage to the immune system.
4. Increased embryonic mortality in animals and humans.
5. In plants too, there will be an increased death rate of seedlings, increased incidence of harmful mutations and reduction in yields

Diversity in Living Organism Long Answer Questions

Directions: Give answer in four to five sentences.

Question 1. What are the characteristic features of the Phylum Fungi? Give examples also.
Answer:

Characteristic features of the Phylum Fungi:

• Fungi includes heterotrophic eukaryotes. These fungi are heterotrophic as they do not have chlorophyll and cannot prepare their own food by photosynthesis, live as saprophytes, parasites and symboints.
• The cell has well defined nucleus and organelles. Cell wall is made of chitin, a complex nitrogen containing sugar that imparts toughness to cell wall.
• Mostly multicellular, only yeast is unicellular.
• Plant body consists of thread like hyphae (network is called mycelium).
• Reproduction occurs by spore formation.

Examples: Rhizopus (pin mould), Aspergillus, Penicillium and Mushroom (Agaricus, an edible fungus).

Read And Learn More: NEET Class 9 Biology Long Question And Answers

Question 2. Mention the general characteristics, and classification of Phanerogams (Spermatophyta).
Answer:

Phanerogams (Spermatophyta) are divided into Gymnosperms and Angiosperms.

Gymnosperms:

1. The seeds are naked.
2. Are perennial, evergreen and woody.
3. Have well-developed vascular issues (xylem and phloem) for transport of materials within the plant body. Xylem lacks vessels and phloem lacks companion cells.
4. Reproductive organs are present in the cones.
5. External water is not required for fertilization.

Examples: Cycas, Pinus, Cedrus (Doedar).

Angiosperms:

Angiosperms are flowering vascular plants:

1. Have seeds enclosed within the fruit.
2. Have diverse body forms.
3. Vascular tissues are well developed; xylem contains
4. vessels and phloem contains companion cells.
5. Reproductive organs are flowers.
6. External water is not required for fertilisation.
   Angiosperms include two classes viz. dicotyledoneae and monocotyledonae.
   1. Dicotyledoneae includes plants having two cotyledons in the seed; reticulate venation; tap root system and secondary growth. Examples: Grain, Mango.
   2. The Monotyledoneae group comprises plants, having one cotyledon in the seed; parallel venation; firous root system; secondary growth is lacking. Examples: Wheat, Maize.

Question 3. What are the characteristic features of Platyhelminthes?
Answer:

• The body is flat, leaf-like or tapelike, bilaterally symmetrical (left and right side of the body are similar).
• They are triploblastic (have three germ layers ectoderm, mesoderm and endoderm) with organ system level of organisation.
• Respiratory and circulatory systems are under developed.
• Excretion occurs through flme cells.
• The nervous system is primitive but with brain.
• Mostly parasites, some are free living like Planaria.

Question 4. What are the characteristic features of Reptilia?
Answer:

• Reptilia are r land vertebrates of warmer regions.
• Horny scales are present on skin.
• Exchange of gases take place through lungs only; gills are absent.
• These are tetrapods with pentadactyle limbs.
• Body is divided into head, neck and trunk; tail may or may not be present.
• Heart is three-chambered.
• They are cold blooded.
• They lay eggs, which have a thick shell.

Question 5. How are organisms named and classified?
Answer:

Taxonomy is the science by which organisms are classified and placed into hierarchical categories that reflect their evolutionary relationships. The eight major categories, in order of decreasing inclusiveness, are

1. Domain
2. Kingdom
3. Division or Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species.

The scientifi name of an organism is composed of its genus name and species name. A hierarchical concept was first used by Aristotle, but in the mid-1700s Linnaeus laid the foundation for modern taxonomy. In the 1860s, evolutionary theory proposed by Charles Darwin provided an explanation for the observed similarities and differences among organisms, and modern taxonomists attempt to classify organisms according to their evolutionary relationship.

Question 6. Whales belong to class Mammalia. Mammals are basically terrestrial. Mention the important changes that have occurred in whales which-enable them to lead an aquatic life.
Answer:

Important changes in whales to lead aquatic life are as follows:

1. Fusiform tapering body.
2. Horizontally expanded tail for propulsion.
3. Formation of a thick layer of fat beneath the skin, the blubber.
4. Presence of whale-bone or baleen.
5. Absence of external ear, nostril moved to the apex of the head.

Question 7. What are the characteristic features of Mammals?
Answer:

Characteristics features of Mammals:

1. Body is covered with hair.
2. Skin is provided with sweat and sebaceous glands.
3. Heart is four-chambered.
4. Fertilization is internal.
5. Females have mammary glands to produce milk to nourish their young ones.
6. External ear-pinna present.
7. Eyes have eyelids.
8. Warm-blooded.
9. Respiration through lungs.
10. Body cavity is divided into thorax and abdomen by the muscular diaphragm.

Question 8. Give the characteristics of flatworms, roundworms and segmented worms. Give their phylum
Answer:

Tissues Long Answer Questions

Directions: Give answer in four to five sentences.

Question 1.

1. Which type of epithelium would you expect to find in blood vessels or in the capillaries?
Answer: Simple squamous epithelium is found in the blood capillaries.

Read And Learn More: NEET Class 9 Biology Long Question And Answers

2. What is the site of diffusion of substances between the blood and tissues?
Answer: It promotes the diffusion of gases and other substances between the blood and tissues surrounding the capillaries

3. What type of epithelium would you expect to find in the ducts of the pancreas?
Answer: Simple cuboidal epithelium is found in the lining of the ducts of the pancreas. Simple cuboidal epithelium is adapted for watery secretion.

4. What type of epithelium would you expect to find lining the mouth?
Answer: Stratified squamous epithelium protects against abrasion in the mouth.

“tissues extra questions class 9 “

Question 2. What is the role of dendrite versus axon in neuron function?
Answer: In simple terms, the dendrite is the neuron extension that receives signals at synapses and the axon is the neuron extension that transmits signals to other neurons or muscle cells. Typically each neuron has multiple dendrites that radiate out from the cell body and only one axon that extends from the cell body.

Question 3. With the help of diagrams (if required) describe the various kinds of connective tissues.
Answer:

The connective tissues are office major types:

Areolar tissue: The areolar tissue (Loose connective tissue) is the most widely distributed connective tissue in the animal body. It consists of a transparent, jelly-like sticky matrix containing numerous fires and cells and abundant mucin.

Dense regular connective tissue: It consists of ordered and densely packed fibers and cells. The fibers are loose and very elastic in nature. They are secreted by the surrounding connective tissue cells. This tissue is the principal component of tendons and ligaments.

Adipose tissue: It is primarily a fat-storing tissue in which the matrix is packed with large, spherical or oval fat cells. The matrix also contains fibroblasts, macrophages, collagen fires, and elastic fires.

“class 9 biology chapter 2 tissue questions and answers “

Skeletal tissue: It forms the rigid skeleton that supports the vertebrate body, helps in locomotion and provides protection to many vital organs. Cartilage and bones are examples of skeletal tissues.

Fluid tissue (Blood and lymph): Fluid tissue is also known as vascular tissue. It consists of the flown matrix in which free-floating cells are suspended. The matrix is devoid of fires, flows freely and is not secreted by the cells it contains. Fluid tissue includes blood and lymph.

Question 4. What is connective tissue? Explain tendons and ligaments.
Answer:

Connective tissues of animals serve the functions of binding and joining one tissue to another and form a protective sheath and pack material around the various organs separating them. They do not interfere with each other’s activities and carry materials from one part to another in the body and form a supporting framework of cartilage and bones for the body, etc.

Tendon: Tendons are cord-like, very tough, inelastic bundles of white collagen fires bound together by areolar tissue. The cells present in the tendons are elongated fibroblasts which lie in almost continuous rows here and there. The tendons connect the skeletal muscles with the bones.

Ligaments: Ligaments are cords formed by yellow elastic tissue in which many collagen fires are bound together by areolar tissue. The firoblasts are irregularly scattered. This tissue combines strength with great flexibility. The ligaments serve to bind the bones together. Both tendons and ligaments are examples of dense regular connective tissue

Question 5. Give reasons for

1. Meristematic cells have a prominent nucleus and dense cytoplasm but they lack vacuole.
Answer: Meristematic cells are actively dividing cells hence they contain dense cytoplasm and large prominent nucleus. Since, they are not storage cells therefore lack vacuoles.

2. Intercellular spaces are absent in sclerenchymatous tissues.
Answer: The cells of sclerenchymatous tissues are thick-walled due to the deposition of lignin along the cell wall. they are lignifid, intercellular spaces are absent.

3. We get a crunchy and granular feeling when we chew pear fruit.
Answer: The pulp of pear fruit contains stone cells or grit cells. These are highly lignified and dead sclerenchymatous cells. Because of the presence of stone cells pear fruit gives a crunchy and granular feeling on chewing.

“class 9th tissues chapter “

4. Branches of a tree move and bend freely in high wind velocity.
Answer: Collenchyma provides elasticity to the plant organs. Due to its peripheral position in stem it helps to the branches of a tree to move and bend freely in high wind velocity. Hence, it provides flexibility to the tree.

5. It is difficult to pull out the husk ofa coconut tree.
Answer: The husk of a coconut is made of sclerenchymatous tissue which provides protection and rigidity to it. The lignin presentin sclerenchyma fires actas cement, that is why it is diffiult to pull out the husk ofa coconut.

Question 6.

1. Differentiate between meristematic and permanent tissues in plants.
Answer: Differences between meristematic and permanent tissue Meristematic tissue Permanent tissue

2. Define the process of differentiation.
Answer: The process by which cells derived from meristematic tissues loose the ability to divide and acquires permanent shape, size and function to become permanent tissue is called differentiation.

3. Name any two simple and two complex permanent tissues in plants.
Answer:

Simple tissue: Parenchyma/Collenchyma/sclerenchyma Complex tissue: Phloem/Xylem

Question 7. Explain the “Complex tissue” of plants.
Answer:

• Complex tissues are made up of more than one type of cells. All these cells coordinate to perform common function are two types of complex tissues present in the plant. Xylem and Phloem are two types of complex tissues present in the plant. Both are conducting tissues and form a vascular bundle.
• Xylem consists of -Tracheids, Vessels, Xylem parenchyma and Xylem fires. Most of these cell are dead. These allow the water transportation, parenchyma stores food and helps in the sideways conduction of water.
• Phleom is made up of Sieve tubes, Companion cells, Phloem fires and phloem parenchyma. It helps in the transportation of food in both the directions from leaves to roots.

Question 8. Show the types of Animal tissues using flow chart.
Answer:

Question 9. Describe ‘epidermis’ in plants.
Answer:

• The Epidermis forms the outermost layer of plants present on entire outer surface of plant. It is made up of single cell layer. It protects all the internal parts of the plant.
• The epidermis secretes waxy, water-resistant layer on their outer surface.
• This helps in protection against loss of water, mechanical injury and invasion of parasitic fungi.
• In leaves epidermis consists of small pores called stomata. These pores helps in the transpiration and exchange of gases, like oxygen and carbondioxide for plants.
• The Epidermis helps in the water absorption in roots. In desert plants epidermis has a thick waxy coating of cutin acts as water proofig agent.

Question 10. What is skeletal connective tissue? Give its functions.
Answer:

Skeletal connective tissue is that connective tissue in which the matrix is solid and the living cells occur inside flied filed spaces called lacunae. It is of two types, cartilage and bone.

“which tissue makes the plant hard and stiff “

Functions of Skeletal connective tissue:

1. Endoskeleton: It forms the internal supporting framework of the animal body.
2. Protection: The tissue protects the vital organs like brain, spinal cord, heart, lungs, etc.
3. Joints: The tissue forms joints which allow for growth and movement of body parts.
4. Muscles: It provides a surface for attachement to muscles.
5. Blood Cells: They form inside red marrow of bones.
6. Minerals: Bony skeleton stores minerals, some of which are withdrawn by the body in case of emergency.

• NEET Biology Class 9 Chapter 1 The Fundamental Unit of Life Long Question And Answers
• NEET Biology Class 9 Chapter 2 Tissues Long Question And Answers
• NEET Biology Class 9 Chapter 3 Diversity in Living Organism Long Question And Answers
• NEET Biology Class 9 Chapter 4 Why Do We Fall Ill Long Question And Answers
• NEET Biology Class 9 Chapter 5 Improvement In Food Resources Long Question And Answers
• NEET Biology Class 9 Chapter 6 Natural Resources Long Question And Answers

• NEET Biology Class 9 Chapter 1 The Fundamental Unit of Life Short Question And Answers
• NEET Biology Class 9 Chapter 2 Tissues Short Question And Answers
• NEET Biology Class 9 Chapter 3 Diversity In Living Organisms Short Question And Answers
• NEET Biology Class 9 Chapter 4 Why Do We Fall Ill Short Question And Answers
• NEET Biology Class 9 Chapter 5 Improvement In Food Resources Short Question And Answers
• NEET Biology Class 9 Chapter 6 Natural Resources Short Question And Answers

Natural Resources Short Answer Questions

Directions: Give an answer in 2-3 sentences.

Question 1. Summarize the major types of global change caused by humans.
Answer: Major types of global change caused by humans include land and water transformation, changes to the chemistry of the earth (for example, changes to nutrient cycles), increases in biological invasions, and increases in the extinction rate of species.

Read And Learn More: NEET Class 9 Biology Short Question And Answers

Question 2. What roles do microorganisms play in the carbon and nitrogen cycles?
Answer: Carbon accumulates in wood. Microorganisms and fungi break down wood and return carbon to the biogeochemical cycles. If these organisms become absent, carbon would accumulate in the wood, where it could not be recycled into the environment. The function of nitrogen is dependent on microorganisms mostly.

3. State two harmful effects of Ozone hole or Ozone layer depletion.
Answer:

1. Ozone layer depletion allows harmful ultra-violet radiations to reach the earth’s surface that may cause skin cancer and cataracts.
2. UV rays also ionize the cells and change the gene structure in animals and plants.

Question 4. How can lichen help in indicating the pollutants in the air?
Answer:

Lichens are very sensitive to the levels of contaminants like sulphur dioxide in the air. Lichens generally grow on the bark of the trees. The trees on the road-side do not show this lichen growth, if in any area the growth of lichens decreases or vanishes the air will be polluted

Question 5. Why is Earth a unique planet on which life exists?
Answer:

Life exists on earth because many factors are responsible for the life to sustain.

1. Ambient temperature
2. Atmosphere
3. Water

Question 6. How do fossil fuels cause air pollution?
Answer: Fossil fuels, like coal and petroleum, contain small amounts of nitrogen and sulphur. When these fuels are burnt, nitrogen and sulphur are also burnt and produce the oxides of nitrogen and sulphur, which pollute air. The combustion of fossil fuels also increases the amount of suspended particles in air which leads to air-pollution

Question 7. What is acid rain? Give its harmful effects.
Answer: The gases released due to the combustion of fossil fuels are SO₂ , NO₂, andCO₂, these gases remain suspended in the air.

When it rains the rain water mixes with these gases to form sulphuric acid, nitrous acid, and carbonic acid and comes down on the surface of the earth in the form of acid rain.

Harmful effects of acid rain:

1. It corrodes statues, monuments of marble, buildings etc.
2. It makes the soil acidic.
3. It damages crops, plantations

Question 8. Explain the importance of ozone to mankind.
Answer:

• Ozone (O₃) is a molecule of oxygen with 3 atoms of oxygen. It covers the earth’s atmosphere and is present in the stratosphere. It does not allow the harmful ultra-violet radiation coming from the sun to enter our earth.
• These ultraviolet radiations cause an ionizing effect and can cause cancer and genetic disorders in any life form. The ozone is getting depleted at the south pole near Antarctica.
• The ozone depletion is due to the halogens like CFC (chloroform carbon) released in the air. Chlorine fluorine reacts with the ozone and splits it, thereby leading to the formation of a big hole called an ozone hole.

Question 9. How does oxygen occur in nature? Explain the oxygen cycle in nature.
Answer:

• Oxygen exists in two different forms in nature.
• These forms occur as oxygen gas 21% and combined form in the form of oxides of metals and non-metals, in the earth’s crust, atmosphere and water. It is also present in carbohydrates, fats, and proteins.

Oxygen cycle, Oxygen from the atmosphere is used up in three processes, namely combustion, respiration and the formation of oxides of nitrogen. Oxygen is returned to the atmosphere by a process called photosynthesis.

Question 10. What is air pollution? How is it caused? Give its 2 harmful effects.
Answer:

The contamination of air with unwanted gases, particles like dust etc. which makes it unfit for inhalation is called air pollution

Causes :

1. Burning of fossil fuels releases SO₂ , CO₂, and NO₂ gases, causing acid rain.
2. Burning of fuels releases unburnt carbon particles, and smoke.
3. Smoke from industries

Harmful effects :

1. It causes respiratory problems.
2. Diseases like allergies, asthma, cancer and heart disease are caused.

Question 11. Name respiratory diseases that may occur due to air pollution.
Answer: Bronchitis, asthma, lung cancer, tuberculosis.

Question 12. List the main sources of water pollutants.
Answer:

1. Sewage
2. Industrial wastes
3. Synthetic soaps and detergents
4. Fertilizers and pesticides
5. Petroleum oil
6. Heat

Question 13. What are inexhaustible resources? Give examples.
Answer: These are present in unlimited quantity in nature and are not likely to be exhausted by human use, for example, air, and solar energy.

Question 14. Give two ways in which carbon dioxide is found.
Answer:

1. Green plants, through photosynthesis, convert CO2 to glucose in the presence of sunlight.
2. Many marine animals use carbonates dissolved in sea water to form their shells.

Question 15. What are non-biodegradable substances?
Answer:

There are substances which can not be broken down by the activity of micro-organisms. These go on concentrating trophic levels of the food chain, e.g., DDT, heavy metals (mercury, cadmium etc.)

Question 16. Name two types of biogeochemical cycles.
Answer: Gaseous cycles and sedimentary cycles

Question 17. Differentiate between humification and mineralization.
Answer: Humiliation is the process by which simplified detritus gets converted into dark-coloured amorphous substance humus in the soil.

Question 18. What do you mean by hygroscopic water and combined water in the soil? Are these available to plants?
Answer:

Some water in the soil forms an extremely thin, tightly held firm around the soil particles. It is called hygroscopic water. In the soil, a small portion of soil water is chemically bound with soil materials. It is called combined water. Both these types of water in the soil are not available to plants for absorption by their roots.

Question 19. Name two freshwater sources that provide fresh water for human use.
Answer:

1. Groundwater.
2. Surface water (ponds, lakes, streams rivers etc.)
   

Question 20. List two bacteria that bring about nitrification.

1. List one denitrifying bacteria.
2. List any two bacteria that play a role in biological nitrogen fixation.

Answer:

1.  Nitrobacter, Nitrocystis.
2. Pseudomonas.
3. Azotobacter, Rhizobium leguminosarum

Question 21.  List at least three gaseous air pollutants that are emitted from automobiles and industries. Also their harmful effects on the health of human beings.

Answer:

1. Three common gaseous pollutants are sulphur dioxide (SO₂), oxides of nitrogen (NO_x) and carbon monoxide (CO).
2. When SO₂ and (and NO_x) are inhaled, these may cause bronchitis, asthma and lung cancer. Carbon monoxide inhalation may result in carbon monoxide poisoning

Question 22. Mention any three human activities that are responsible for the depletion of the ozone layer.
Answer:

The human activities responsible for the depletion of the ozone layer are :

1. Excessive use of chlorofluorocarbons (CFCs)
2. Nuclear testing
3. Excessive use of nitrogenous fertilisers
   

Question 23. Name two diseases caused by

1. Infectious agents in polluted water.
2. Toxic chemicals in polluted water.

Answer:

1. Diseases caused by infectious agents in polluted water are cholera and typhoid.
2. Diseases caused by toxic chemicals in polluted water are cancer and arsenicosis

Question 24. Why are chlorofluorocarbons supposed to be responsible for the depletion of the ozone layer? Explain.
Answer: Chlorofluorocarbons are inert, highly stable, colourless and odourless chemicals extensively used in refrigerators and air conditioners.

• Chlorofluorocarbons are nontoxic in the troposphere, but they slowly diffuse into the stratosphere where, under the influence of high-energy radiation, they break to produce chlorine atoms.
• Chlorine atoms react with ozone in the stratosphere to produce chlorine monoxide and O2. Chlorine monoxide reacts with atomic oxygen to regenerate chlorine. A single chlorine atom can destroy about 1,00,000 ozone molecules
  

Question 25. How do organisms help in soil formation?
Answer: Soil formation occurs in steps. due to weathering, parent rocks break into gravel sand, silt and clay, which become habitats for a large variety or organisms like algae, fungi, helminths, insects, frogs, reptiles, rodents, etc. Death and decay of these living forms provide organic matter which combines with inorganic matter derived from the parent rock to form humus, which finally develops into mature soil.

Question 26. What will happen if nitrogen fixation does not take place?
Answer: The majority of organisms will not be able to use atmospheric nitrogen directly. Through the process of fiation, free nitrogen is converted into ammonia and nitrate, which is taken up by plants to be converted into amino acids, nucleotides, proteins and other nitrogenous compounds. In the absence of the nitrogen fixation process, these substances, which are necessary for the structural and functional growth of organisms, will not be formed.

Question 27. How can we prevent the loss of topsoil?
Answer: The upper A-horizon of soil is called top soil. It contains most of the litter, humus and roots of small plants embedded in it.

Question Loss of top soil can be prevented by the following ways :

1. By preventing deforestation
2. By preventing excessive grazing of grasses and small plants by herbivores.
3. By preventing plantation and increasing the vegetational cover
   

28. All living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms? Discuss.
Answer: The substances like C, N, S, P, H and O enter the living body through biogeochemical cycles. The atmospheric carbon (CO2) is used by plants during photosynthesis to synthesise carbohydrates.

• When animals feed upon the plant products, carbon enters into the animal’s body. Phosphorus and sulphur are absorbed by plants from the soil.
• Animals obtain it through food and water. Oxygen enters into plants’ and animals’ bodies through the process of respiration.
• Hydrogen enters into plant bodies through absorbed water and into animals’ bodies through food and water. Plants absorb nitrogen from soil as nitrates and nitrites and convert them into proteins. When these plants are eaten by animals, nitrogen enters into the animal’s body
  

Question 29. Why are root nodules useful for the plants?
Answer:

The roots of leguminous plants bear nodules. Nitrogen bacteria, Rhizobium reside inside these modules. Rhizobium can directly utilise atmospheric nitrogen and convert it into nitrogenous compounds like ammonia and nitrates. In this way plants get easy access to these chemicals which are good for plant growth. This is the reason that root nodules are useful for plants

Question 30. Why does water need conversation even though large oceans surround the land masses?
Answer: Water constitutes more than 70% of the total earth’s surface. Out of the total water resources only 2.7%, which is fresh water, is used by human beings for themselves or for agriculture and animal husbandry. Marine water is not uniformly available over the different parts of the earth.

Even at a particular place the demand and availability of fresh water differs according to season and climate. The demand for fresh water is likely to increase with the rising population, so it is essential to conserve this natural resource through proper management.

Improvement In Food Resources Short Answer Questions

Question1. What are the differences between mixed cropping and intercropping ?
Answer:

Read And Learn More: NEET Class 9 Biology Short Question And Answers

Question 2. What are the advantages ofusing manures in the crop filds?
Answer:

Advantages ofusing manures in the crop filds are:

1. They improve fertility of the soil by providing mineral nutrients to the soil.
2. Improve soil texture by adding organic matter to the soil. Organic matter increases water-holding capacity of sandy soil. It improves drainage in clayey soil by preventing water logging.
3. Use of organic manure helps in recycling of farm waste, saving the environment from excessive use of fertilizers.
4. They provide food for soil organisms, which keep the soil in a healthy, balanced condition.
5. Manures do not cost anything to the farmer as he prepares it from the farmyard wastes.

Question 3. What are the differences between broilers and layers and in their management ?
Answer:

Differences between broilers and layers and in their management are:

Question 4. Why is use of excess fertilizer determental for environment?
Answer:

Use of excess fertilizers will cause:

1. Mineral loading of underground water.
2. Excess minerals in the crop plants.
3. Salination of soil.
4. Run off from fertilizers rich soil, will cause eutrophication of water bodies.

Question 5. What are micronutrients?
Answer: The mineral elements required by plants in trace or micro amounts are called micronutrients. They are iron, manganese, boron, zinc, copper, molybdenum and chlorine.

Question 6. What is plant tissue culture? What are the important steps involved in it?
Answer: The growth of plant tissues in an artificial environment (or culture medium) outside the parent organism (in vitro) is called tissue culture. It involves the following important steps:

1. Removal of tissues from parent organism.
2. Inoculation of explant (excised tissue) in suitable culture medium.
3. Incubation of excised tissues in a conducive environment.
4. Maintenance of culture for future use.

Question 7. Some ofthe high yielding varieties ofcrops are Ganga-101, Sonara-64, Pusa-205, Jaya, Arjuna,

1. Which of these represents wheat?
2. Which of these represents rice?
3. Which of these represent maize?

Answer:

1. Wheat-Sonora-64, Arjuna.
2. Rice-Pusa-205, Jaya
3. Maize-Ganga-101

Question 8. Distinguish between

1. Inland fishery and marine fishery
2. Culture fishery and capture fishery
3. Aquaculture and pisciculture

Answer:

1. Inland fihery is the rearing of fih in freshwater whereas marine fihery is the rearing of fih in sea water.
2. Culture fihery is the raising offih in ponds and tanks whereas capturing vis management of catching of fih without raising them.
3. Aquaculture is rearing andmanagementoffih, oysters, mussels and other aquatic animals and plants. The pisciculture is rearing, catching and management of catching offih

Question 9. What type ofinsect pests are found in our crop filds? Name any three of them.
Answer: Harmful creatures for our crop plants are small insects which attack the plants in three ways :

1. Chewing insect : Insect pests of this category cut the root, stem and leaf with the help of their chewing mouthparts. They chew and swallow these pieces of plant parts. Examples, Grasshoppers, Caterpillars, Locusts, etc.
2. Sucking insects : These insects puncture the plant parts and suck the cell sap with the help of their needle like hollow beaks. Examples, Leaf hoppers, Aphids, Bugs, etc.
3. Internal feeders : These insects bore into stem and fruits. They live inside the plant parts and harm the crop yield. Examples, Weevils, Borers, etc.

Question 10. How do plants get nutrients?
Answer: Plants obtain nutrients from air, water and soil. Air is the source of carbon and oxygen. Hydrogen is obtained from water. The remaining thirteen elements are got directly from soil through root absorption.

Question 11. What is the inflence ofbreeding in milk production?
Answer: The quality and quantity of milk of some breeds is comparatively much better than others. For example, exotic or foreign breeds of cattle have long lactation periods and give more amount of milk. Jersey cows (Native of Island of Jersey, U.S.A.) and Brown Swiss cows (Native ofSwitzerland) produce on an average 60 litres ofmilk in a day. On the other hand, local breeds (for example, Red Sindhi and Sahiwal) produce on an average only 6-8 litres of milk per day. Milk of Red Sindhi cow contains higher fat than those of Holstien (Native of Holand) and Brown Swiss).

Question 12. What do you mean by the following ?

1. Green revolution
2. White revolution
3. Blue revolution
4. Yellow revolution

Answer:

1. Green revolution: Revolution in the increase of food grains (especially wheat)
2. White revolution: Revolution in the increase of milk
3. Blue revolution : Revolution in fih production
4. Yellow revolution: Revolution in production of oil seeds.

Question 13. What would happen if poultry birds are larger in size and have no summer adaptation capacity? In order to get small sized poultry birds having summer adaptability, what method will be employed?
Answer: Larger sized birds require more feed. Summer adaptation is connected with egg laying. Little summer adaptation reduces egg laying. In order to obtain small sized poultry birds having summer adaptability, it is desirable to

1. Either introduce the required exotic birds from outside and
2. Cross-breed the local birds with exotic birds from outside.
   • Small-sized birds are preferred for
   • Lower requirement of feed
   • Higher egg-laying capacity
   • Lower requirement for space.

Question 14. What is Organic farming?
Answer: It is the farming in which no chemical fertilizers, pesticides or herbicides are used. But uses of all organic matter for its growth like manure, seem leaves as pesticides, grain storage.

Question 15. State the difference between manure and fertilizer.
Answer:

Question 16. Name a few varieties of bees used for commercial honey production.
Answer:

Question 17. How are crops useful to us? What do they provide?
Answer: Crops provide us food for our daily body nutrient carbohydrates for energy requirement-like cereals such as wheat, rice, and maize.

Protein for bodybuilding: Pulses like grams, lentils.

Fats for energy – mustard, sunflower Vitamin, and minerals – from vegetables, spices and fruits.

Fodder crops – for livestock.

Question 18. What are the new variety traits obtained by cross-breeding of Indian and exotic Qbreeds of poultry?
Answer: The cross-breeding of Indian and exotic breeds for variety improvement and getting

The following traits.

1. Number and quality of chicks.
2. Dwarf broiler parent for commercial chick production.
3. Summer adaptation capacity/tolerance to high temperature.
4. Low maintenance requirements.
5. Reduction in the size of the egg-laying bird with the ability to utilize more fibrous cheaper diets formulated using agricultural by-products.

Question 19. What are fertilizers? Excess use of fertilizers is not advisable. Explain.
Answer: Fertilizers are obtained artificially on commercial basis. It is a chemical which contains the nutrients required for the crop to grow. Fertilizers supply various nutrients as they are nutrient specifi example.-Urea provides-Nitrogen. Mixed fertilizer provides any two mixture of nutrients. They are expensive but the use yield large production hence are a factor of high-cost farming. Excessive use of fertilizers are not advisable as :

1. It leads to soil and water pollution.
2. It can destroy the fertility of soil. As the soil is not replenished, micro-organisms in the soil are harmed by fertilizers.

Question 20. Name the sources and the nutrients supplied by them to the plants.
Answer:

Question 21. How do insects pests attack the plant and affect it?
Answer: Insect pests attack the plants in three ways:

1. They cut the root, stem and leaf.
2. They suck the cell-sap from various parts of the plant and.
3. They bore into stem and fruits. This way they affect the health of the crop and reduce yields.

Question 22. What are the factors for which variety improvement of crop is done?
Answer:

1. Higher Yield: It helps in the production of crop.
2. Biotic and Abiotic Resistance: Crop should be resistant to biotic factors like diseases, insects, pests and abiotic factor like drought, salinity, heat, cold, frost and water logging.
3. Change in maturity Duration: Short-duration maturity allows farmer to grow more crops in a year and reduces the cost of crop production.
4. Wider Adaptability: Crop should be able to adapt to changing environmental conditions.
5. Desirable agronomic Characteristics: The tallness and dwarfness of crop. Dwarfness required for cereals, so that less nutrients are consumed

Question 23. What do you mean by exotic fihes? Name three important exotic fihes that are being cultured in India.
Answer: A number offih species have been imported from foreign countries and introduced into Indian fresh water for culture. Since, these fihes are not the natives ofthis country, they are called as exotic fihes. The three important exotic fihes used as food fih are :

1. Common carp
2. Silver carp
3. Grass carp

Question 24. What do you mean by animal husbandry? Mention the important aspects of this branch of science.
Answer: Animal husbandry is the branch of agriculture that deals with the rearing, feeding, breeding, improvement and caring of domesticated animals.

The important aspects of animal husbandry are :

1. Providing proper shelter to animals
2. Providing proper food to animals
3. Taking care of animals against diseases
4. Using proper breeding technique for breed improvement.

Question 25. There are four varieties of poultry birds: Aseel, White Leghorn, Busra and Rhode Island Red. Which are indigenous and which are exotic? What would be the advantage of crossing indigenous species with exotic ones?
Answer: Indigenous varieties are Aseel and Busra; Exotic varieties are White Leghorn and Rhode Island Red. By crossing indigenous and exotic breeds, improved quality of commercial egg-laying and more flsh-producing birds can be produced.

Question 26. “If we use pesticides excessively in order to safeguard the crop from blight, it may cause long term damage to mankind”. Justify the statement.
Answer: Excessive and indiscriminate use of pesticides causes air, water and soil pollution and adversely affects human beings. The pesticides are either inhaled or taken through food and drinks. They accumualte in the body and may get biologically magnifid with time as they pass through the food chain. Pesticides have been reported to induce cancer, growth of tumours and have mutagenic effect in man.

Question 27. ‘The production of food from animal sources has increased greatly in the last few decades’. Justify it.
Answer: The ever increasing human population and the consequent decrease in agricultural land has compelled us to move towards animal husbandry to obtain food from animal sources. The last few decades have seen an enormous rise in animal meat production and by-products. Poultry, fiheries, piggery cattle, sheep and goat farming have developed considerable. Through operation flood and the silver revolution, milk and egg production have registered a record increase.

Question 28. A farmer was advised not to use a particular type of fertiliser for his crop after harvesting a crop of peas. Give one reason for such an advice. Name any two crops other than pea which would have shown the same effect.
Answer: Nitrogen fiing symbiotic bacteria (e.g. Rhizobium) remain associated with the root nodules of pea plant. These bacteria enrich the soil with ammonia and nitrate necessary for plant growth. Hence, a farmer need not use nitrogenous fertilisers in the fild after harvesting a crop of peas. Besides peas, gram (chana) and green pea (moong) also show the same effect.

Question 29. What are biofertilizers? In what sense are they better than chemical fertilizers?
Answer: Some microorganisms like nitrogen fixing bacteria, cyanobacteria, fungi and other microflra harbour near the roots of plant inside soil. They enrich the soil with nutrients and improve soil fertility, hence are collectively called as biofertilisers.

Question 30. What factors may be responsible for loss of grains during storage?
Answer: Both biotic and abiotic factors are responsible for the loss of stored grains. Abiotic factors include improper temperature of store house, humidity of air and high moisture content of the grains. Improper containers used for storage also cause loss of grains. Biotic factors include insect infusion, mites, birds, rodents, diseases caused by microorganisms and enzymatic actions occuring within food grains.

Question 31. Name any two plantation crops and two commercial crops.
Answer:

• Plantation crop – tea, coffee.
• Commercial crops – cotton, jute

Question 32. What are the different systems of irrigation?
Answer: Some common irrigation systems are dug wells, tube wells, canal system river lift system and tanks

Question 33. Write the name of one indigenous and one foreign breed of poultry bird.
Answer:

• Indigenous breed : Aseel
• Foreign breed: Leghorn