Conservation Of Plants And Animals
Forests are vital to the survival and well-being of people everywhere all 7 billion of us. Forest is the wide range of land area occupied by plants. Forests are the dominant terrestrial ecosystem of Earth and are distributed across the globe. Nearly one-third of the earth’s land (33%) area is covered by forest. Forest is the home of 80% of our terrestrial biodiversity.
According to World Bank estimation, more than 1-6 billion people depend on forests for their livelihood and some 300 million live in them. The forest product ‘ industry is a source of economic growth and employment. Forest cover 21% of the total land area of India.
Read and Learn more WBBSE Notes For Class 8 General Science And Environment
However, the total global forest area has started to shrink at an alarming rate.
More over we use more than 5000 forest products in daily life directly or indirectly. It has been estimated that a tree lives for about 50 years it emits 2700 kg of oxygen in its 50 years lifetime. ‘ If you observe two localities near the forest and far from the forest you will get a clear idea about the benefits of the forest. Makg a table of these benefits.
Make a list of your daily use articles and find out its plant source :
| Articles | Plant products | Sources |
| 1. Pencil | ||
| 2. Scale (wooden) | ||
| 3. Eraser | ||
| 4. Dress/clothes | ||
| 5. Medicine | ||
| 6. Food products | ||
| 7. Mat | ||
| 8. Hand fan | ||
| 9. Threads | ||
| 10. Fuel | ||
| 11. Sitting arrangements |
Types Of Forest:
Broadly there are three major forest zones. They are separated to their distance from the equator.
1. Tropical forest:
Near the equator having the greatest diversity of species. It has two distinct seasons rainy and dry no winter. Soil is nutrient poor and acidic. Rainfall 200 cm or more, temperature 20-25°C. Canopy in tropical forests is multilayered and continuous, allowing little light penetration.
Trees are mostly evergreen with large dark green leaves. Different types of birds, bats, small mammals and insects are the main animals.
2. Temperate forest:
Forest in between pole and equator. Temperate forests have well-defined seasons with distinct winters. Temperature -30°Cto 30°C, rainfall 75-150 cm. Soil fertile enriched with decay litter. The canopy is moderately dense and allows light to penetrate. Flora-oak, hickory, beech, maple etc. Fauna – squirrels, tigers, lion, deer, birds, etc.
3. Taiga or boreal forest:
Present near the pole. Seasons are too short, and moderately warm summer and long cold and dry winter. Temperature are very low, rainfall 40-100 cm, and soil nutrient-poor and acidic. Canopy permits low light penetration, so the understory is limited.
Flora-cold tolerant evergreen conifers with needle-like leaves-pine, fir. Fauna – wood packers, hawks, moose, bear, fox, wolf, deer, hares, shreaws, bats etc. very few reptiles. There are also some more specific types of forests within these larger regions.
Several types of forests are found in different geographical areas and this is due to changes of climate. Among the total forest area, 95% is natural forest and 5% is cultivated forest. South America covers 23% forest area while Oceania have 5%. Forest plants with needle-shaped leaves are—Pine and oak.
The tropical rainforest has more kinds of trees than any other area, distributed near the equator. 10 countries of the world have no forest area and another 64 countries have less than 10% forest area.
Amazon rainforest –
The Amazon river basin rainforest contains a wider variety of plant and animal life than any other biome in the world.
| Forest type | Forest-plant leaf | Plant | Animals |
| Conifer/Taiga | needle-shaped leaves | Pine, oak | Black bear, Leopard, owl |
| Deciduous forest | normal leaves shaded periodically | Teak, Shal, Arjun, Amloki | Tiger, Bison, Elephant |
| Evergreen forest | Normal green leaves, plants having leaves throughout the years | Mango, Banyan, Rose, Apple | Tiger, Deer, Peacock Monkeys. |
| Bushy Desert / Dry area forest | Thorny bushy plant | Babul, Cactus | Blackbuck, Jackal, reptiles |
| Savana—grassland | Grass with long leaves | Different types Purundi | Rhinoceros, Deer, Zebra of grass, Hogla, |
| Mangrove forest | breathing roots and glossy green leaves | Goran, Gewa ‘ | Tiger, Deer, Pig, Crocodile |
Below there are some plants and animals choosing from list of 3/4 food chain, mentioning producers, consumers – (herbivores and carnivores)
| Grasshopper | Grass | Tiger | Banyan |
| Grass | Eagle | Leopard | Bear |
| Toad | Hare | Fish | Oak |
| Snake | Jackal | Otter | Pine |
| Peacock | Rhinoceros | Mongoose | Bat |
| Earthworm | Termites | Crab | Squirrel |
| Bamboo | Owl |
Components of the forest :
Evergreen forests such as the Amazon rainforest and the tropical rainforest consist of many components divided into two categories that are living or biotic and non-living or abiotic factors.
Biotic components include trees, shrubs, vines, grass and other herbaceous (non-woody) plants-mosses, algae, fungi, microorganisms, and different types of animals. Abiotic factors are humidity, sunlight, wind, rainfall, soil, etc.
If you notice the plants in the forest you will find plants are of different lengths. Therefore, different layers are formed. In a typical forest, there are four layers such as- tropical forest flora and fauna are highly diverse. One square kilometre may contain 100 different tree species.
1. Emergent layer:
The uppermost layer of tropical rainforest. Tall trees reach the level and spread out usually with the straight branch, and free trunks with crowns on the tops. They are about 100 ft. to 200 ft tall with supporting buttress roots spread up to 20 – 30 ft.
Trees have small pointed leaves this type of adaptation for speedy wind. Animals found in this layer—are bats and birds.
2. Canopy:
The second upper layer below the emergent layer is 100 ft and below that. It is the thickest layer of forest usually form the roof of the forest. The Canopy is the layer that stops sunlight and rainwater from getting to the layer below it.
Canopy is formed by the mass of intertwined branches twigs and leaves of the mature trees forming the crown of the forest getting most of the sunlight. It is the most productive part. Some rootless plants grow in this layer also.
Canopy is the cover formed by the leafy top branches (roof) of the tallest trees in the forest. Millions of insects and other animals are present in this layer as they have enough food to keep them there. Common animals include squirrels, monkeys, reptiles, bats and a variety of birds and tree dwellers many mammals also present there.
3. Understory:
Below the canopy is made up of bushes, shrubs, and young trees. (12 ft. upto) they are adapted to live in the shades. This layer has many vines, dense vegetation but not much sunlight reaches here, it is blocked by the canopy layer. Animals like small birds, frogs, beetles, termites, snakes, butterfly etc. This part is wet and humid dark in nature.
4. Forest floor:
The ground layer is dark, and damp and contains decomposing leaves, animal droppings and dead trees. Different types of ferns, moss, mushrooms and other fungi and tree seedlings grow here. Large mammals like tigers, elephants etc. frogs, toads, lizards, and insects, are the common animals. Animals that are found here both herbivores and carnivores.
Conservation Animals
They include scorpions, armadillos, wild cats, mongooses, lizards and a variety of insects. The tropical rainforest has more kinds of trees than any other area in the world. 70% of the plants in rainforests are trees. Thundershowers on an average occur 200 days out of 365 days in a year, in the tropical rainforest creating a very humid atmosphere.
The trees of tropical rainforests are so densely packed that rain falling on the canopy can take as long as 10 minutes to reach the ground. The first forests were dominated by giant horsetails, club mosses, and ferns that stood up to 40 feet tall nearly 38 million years ago.
Boreal forests (= Taiga) can be found in the broad belt of Eurasia and North America. Two-thirds in Siberia with the rest in Scandinavia, Alaska and Canada. Taiga covers 11% of the earth’s land area.
Loss of forest :
We destroy 130000 sq. km of forests every year. Rainforests once covered 14% of the earth’s land surface now they cover a mere 6%. More than half of tropical rainforests have already been destroyed.
Deforestation :
It is the removal or decrease of deterioration of forest cover of an area. Indian forests comprise nearly 1% (one) of the world’s forest area, India is losing about 1.5 million hectares of forest cover each year.
Causes of deforestation :
Deforestation is mainly due to the following reasons-
A forest fire and its damage :
A forest fire is an uncontrolled fire that occurs in a forest area. Forest fire is one of the causes of loss of the natural habitat of plants and animals. About 1% (one) of forests roughly the size of New Zealand are consumed by fire each year. Nowadays most forest fire are caused by humans.
Factors responsible for forest fires are —
Damage caused due to forest fire :
Forest conservation :
Forest conservation is the protection, restoration and preservation of forests.
The development of forests in the denuded region is called reforestation and the creation of forest over the base area is called afforestation. Forestation is must for slopes and hills. In West Bengal forest arear nearly 13-38%. Among them, two main forest areas are the Forests of North Bengal and the Mangrove forests of Sundarban
West Bengal has a forest cover of 1-19 million hectares much of which is in the Darjeeling and Dooars region.in North Bengal. There is a tiger reserve in the region known as Buxa Tiger Reserve (BTR) wildlife sanctuaries at Jaldapara and Mahananda National Park, Gorumara, Neora Valley and Sangalila.
The forests of North Bengal have rich diversity of flora and fauna. Sal occupies nearly 80% of all vegetation in the tropical forest other plants are Gamhar, Odal, Khair, Sishu etc. and different types of orchids are found here. A variety of mammals, reptiles, and rare species of trees are found.
Besides the one-horned Rhinoceros, The fauna of the area includes the Asian elephant, Gour, Leopard, and Deer. The vegetation changes with altitude in North Bengal. The plains of the foothills are covered by sal, as soon as the altitude increases vegetation changes in the higher altitude region. Rhododendron, Magnolia, Oak, Hemlock, Silver Fir, different types of bamboo, etc.
Ferm’s wild grasses are common. Several tea gardens have been set in this area. In the cool climate rare species of mammals like red panda, Snow leopard, Gour, Elephant, Himalayan Black Bear and different types of birds are found here. In Jaldapara endemic species of Rhinoceros (R unicorns) is found. Now the forest and adjacent area faces different types of problems.
The forests of North Bengal is an extremely rich biodiversity zone but today face a declining Rhino-population and much vegetation. There have been repeated incidents of elephant and Bison death on railway tracks running through the forest of North Bengal.
Most of the cases has been reported from a 100 km stretch of railway track between Alipurduar to Siliguri. The track was converted to. broad gauge line in 2004, allowing an increase in train number and speed, illegal cutting of trees also decreasing the forest area.
Last 50 years population of this area has been increased rapidly. So more and more human villages or habitations have been established and some new Tea garden has also been established or old one extended their area. All these decrease the forest area. Thus the Natural ecosystem is hampered.
In some cases, corridors of elephant passing have been obstructed by developmental work. For this reason, the man and elephant conflict has been started. Death of many elephants have occurred in railway tracks. Elephants sometimes attack human villages and crop fields due to scarcity of food.
Paragraph On Conservation Of Plants And Animals
Not only elephants, leopards, tigers, rhinos, Gour, and Bison are also killed in the conflict. To solve the problem forest department has increased the core and buffer area of the forest. Some elephant corridors has been set up to control the elephant attack. , Incidence of infestation of other wild animals such as Leopard, Bison, also a problem. The scarcity of food is the main reason.
The scarcity of wild natural prey of leopards, change their food habits they are now more and more dependent on capturing goats, cattle, ducks, hens, poultry birds etc. This creates another conflict. Tea Garden labour is sometimes attacked by leopards. In fear, people attack them and killed them.
General awareness to be raised against these killings. Sometimes elephants migrate from other places’ neighbourhoods (Dalma Hills) and refuse to return their native place. These create also problems.
Mangrove forest and their present Crisis :
A mangrove is a shrub or small tree that grows in coastal saline and brackish water. Mangroves occur worldwide in the tropics and subtropics. Mangroves are salt-tolerant trees also called holophytes and are adapted to life in harsh coastal conditions. Mangrove forests are found in the southern tidal areas of West Bengal.
Sundarban forest is mainly a mangrove forest. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are adapted to the low oxygen conditions and water-logged mud. Mangrove plants have respiratory roots and many of these plants have stilt roots.
Respiratory roots, the upward-directed root branches with pores (pneumatophore) helps them to continue their breathing of roots in muddy or water-covered condition. Stilt roots help them to attach with the soil that not extirpated the plant during high tide.
The lower part of plants like the base of mangrove plants like Byne, Keora, Pasur, and Garan became submerged twice under water during high tide. Some mangrove plants (Rhizophora species) Garjan, Garan, Kanura and same other seeds germinated inside the fruit before falling to the soil.
This is due to avoid germination in saline water where they may wash out by tidal water. This type of germination is known as viviparous germination.
1. Nowadays due to the deposition of silt in the river basin of different rivers going through this mangrove forest and due to the raise of the sea-water level the water level raise and more marine water flow inside rivers therefore, the salinity of water of this area raise.
This comparatively high saline water (33 – 38 gm / 1000 gm marine water) enters inside the creeks directly. Plants of terrestrial lands are unable to tolerate more salty water. Excess salt cause toxicity in the tissues of plants.
Plants try to eliminate excess salt through leaves and roots but still they face problems and rise of water levels in creeks (Khauri) causing soil erosion. Roots unable to hold the plants. Some plants loss in this process.
Water and soil pollution, increase water temperature and some unwanting substances from manure and pesticides cause serious damage to the flora and fauna living in this water.
Crocodiles, Turtle and tortoises, crabs, and fishes are under severe threat of extinction. Excessive tourism in this area also causes pollution and damages the ecosystem of this area.
Observation-
Visit this place as much as you can. Identify the plants their and animals as much as you can. The people around this area their activities. Note down the problems.
Many of you have seen and may have collected different types of molluscan (snail) shells, starfish, Jellyfish, octopus, and some hard whitish sleeper-like internal skeletons of Sepia during the walk along sea-shore. Let’s see what is the sea and its environment and biodiversity ar.
The Ocean (sea) is a continuous water mass covering about three-fourths (75/£) of the earth s surface. Most oceans are deeper than two kilometres and are home to some of the most diverse life on the earth.
We are familiar with animals that live on the surface of the ocean where sufficient light penetrators and photosynthesis take place in plants. Where large quantities of diatoms and other phytoplankton are present and they give colour to the sea.
Phytoplankton-
They are small and mainly microscopic. They can produce their food by photosynthesis with the help of sunlight, for example. diatoms, dinoflagellates, blue-green algae etc.
Zooplankton-
They are unable to produce food and feed on other plankton, for example, larval forms of different arthropods, shrimp, krill, etc.
The photosynthetic micro-floating organism is called phytoplankton. These are mainly algae. These are the main sources of food of zooplanktons and many others sea dwellers. Phytoplanktons and some algae-like plants mainly occupy the lighted water column of the sea.
If we go deep down the sea, we will notice the sunlight is gradually dimming (waning) and if we go further down it is pitch dark. The majority of sea dwellers (animals) live in the upper part (surface zone) and gradually their number decreases as the increase of depth and their structural and behavioural patterns also change.
The deep sea zone where living conditions not at all favourable very few types of animals are found there. The pressure there is so immense that we would be crushed if we go down there. The temperature is nearly freezing, food is very scarce and there is no light at all.
A small mainly microscopic diverse collection of aquatic organisms which are unable to swim against the water current drifting or floating in the sea or fresh water. Planktons are mainly diatoms, protozoans, small crustaceans (arthropods) and the eggs and larval stages of larger animals. ‘These are the food sources of many aquatic animals including fish and whales.
Planktons are of two types
Ocenographers divide the open ocean (pelagic /one) into five layers.
1. Sunlight zone
The first layer (epipelagic /one) Oceanography extends up to 200 metres (600 ft) It is the photic j It is the study of different aspects zone or sunlight zone that receive sunlight.
Phyto planktons, zooplanktons and some other animals like Jellyfish, many sharks, dolphins many fishes, (clown fish) f Blue whale feed on plankton, are formed in this zone.
Oceanography
It is the study of different aspects (biology, physics, chemistry, geography, engineering and metrology) of the ocean.
2. Twilight or Dimlight zone (mesopelagic zone)—
The second layer extends from 200 metres to 1000 metres. The intensity of light is low so this layer is known as dim light or twilight zone. Submarines usually use this layer Animals that live here are swordfish, squid, wolffish, and some cuttlefish, whales.
Many organisms that live in this zone are bioluminescent. Some creatures of this zone move to the upper zone at night to feed. The eyes of fish are larger and usually directed upwards, probably to see other animals and for food against the pale light.
3. Midnight zone (bathypelagic zone)—
This is the third layer extending from 1000 metres to 4000 metres. The sunlight doesn’t penetrate deep into this layer. The ocean is pitch black. So this zone is known as the midnight zone. No living plant exists here.
Most animals living here survive by consuming the detritus failling from the zone above. Animals living here are Angler¬fish, Squids, giant squids, octopus, sperm whales, etc.
4. Lower midnight zone or Abyssal zone (abyssopelagic zone)—
This is the fourth layer extending from 4000 metres to the sea floor. No light, immense dark the pitch-black bottom layer. The water here is almost freezing and its pressure is immense. Very few creatures live in this zone.
Animals found in this zone are squid, many echinoderms, marine arthropods, and sea spiders. Many of the species living at these depths are transparent (no pigment) and eyeless because total lack of light in this zone.
5. Hadalpelagic zone-
The zone includes water found in the ocean’s deepest trenches. This zone is mostly unknown. However, some organisms live in hydrothermal vents.
Many living sea organisms are found in the space created in the water level during low tide. The organisms are usually found in algae, snails, mussels, starfishes, sea anemones, crabs etc. Sponge and some other animals fixed themselves with sea bottom and rocky substances. ‘
Phytoplanktons and zooplanktons are usually found near surface common fishes, the octopus whales, eels and squid are found in middle areas, starfish various worms, snails, and oysters are usually bottom dwellers. The intertidal area (= littoral zone) is where the land and sea meet; between the high and low tide zones.
This area is rich in nutrients and oxygen and is home to a variety of organisms. In this area (high, middle and low tide area) sea anemones, chitons, crabs, green algae, mussels, snails, sea cucumbers, sea stars, sea urchins, sponges, and tube worms are found. The intertidal zone is also a good place to find plants in the sea.
Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from the shoreline to the edge of the continental self. Most marine Ijfe is found in coastal habitats.
Here sponges and other marine invertebrates, small fishes, marine turtles, sea cows, sea horses and small marine shrimps, and Kelp, a kind of marine algae also found here. Plant growth is completely absent at the sea bottom. So the deep sea animals have to prey upon one another.
Some deep-sea fishes regularly migrate to feed near the surface, particularly at night. When there are fewer predators around. Mostly the deep-sea animals depend on surface plants and animals that sink to the bottom. Occasionally when a large animal such as a whale, or large fish die on the surface it sinks to the bottom offering a rare feast to deep-sea dwellers.
Coral reefs :
Coral reefs form complex marine ecosystems with tremendous biodiversity. Coral reefs exist in most tropical waters. Reefs are built up by corals and other calcium-depositing animals.
Bioluminescence (cool light) —
This is an extraordinary feature exhibited by the animals living in deep seas (also found in some terrestrial insects such as fireflies). It is a chemical process that results in the release of light through specialized organs called, light organs. Light is produced either through symbiotic bacteria living on the fish or through specialized self-luminous cells called photophores.
Bioluminescence occurs when certain chemicals are mixed together. Chemical reactions occur between luciferin (protein-bound pigment) and oxygen in presence of the enzyme luciferase (catalyzes the chemical reaction). Here chemical energy is converted into light energy.
Most of the light created by marine organisms is blue-green in colour (which not only travels best in water but also many marine organisms are sensitive to this light.) Exceptionally some fishes can also produce red light. (This gives them an advantage by allowing them to see their prey without making their presence Known)
Bioluminescence is very common among fishes, crustaceans, cephalopods (Arthopodes) Cnidarians (Coelenterates), some starfishes and a few animals. Some animals establish a symbiotic relationship with light-producing bacteria.
Importance :
Bioluminescence helps animals in various ways find mates, attract prey, self-defence, search for food etc.
Colouration :
The majority of marine fishes display a wide variety of colours and colour patterns. However, many deep-sea fishes (e.g. viperfish) don’t have any pigment to colour their body, and appears transparent.
The autotrophic (self-feeding) organisms of the sea / or plants of the sea
Phytoplankton-
chlorophyll-containing microscopic organisms live in the euphotic zone (where sunlight reached). They can produce food with the help of sunlight. Phytoplanktons are the main producer of aquatic ecosystems planktons have a role to maintain carbon balance in the environment.
Diatoms—
Diatoms are unicellular algae (phytoplankton) although can form colonies with distinctive transparent cell walls made of silica. They are found in almost all aquatic environments.
Dinoflagellates—
Dinoflagellates are unicellular phytoplankton mostly marine but also found in fresh water. They move with the help of flagella. Some dinoflagellates also exhibit bioluminescence.
Kelp—
Kelp are large brown marine algae seaweeds. Kelp grows in shallow oceans are grows in such a way that they create a forest under the ocean. The body (thallus) consists of flat or leaf-like structure and remains attached with something underwater with the help of a root-like structure (hold fast). They grow very fast.
1. Zooplankton-
Zooplanktons are very small some are microscopic flea-swimming organisms that drift with water currents. The zooplankton community is an important element of the aquatic food chai the most abundant group of animals in the world’s ocean.
The Baleen hales r zooplankton, especially one species in particular called Krill, for example, larval forms of different arthropods, shrimp, kri etc.
2. Sea anemone-
You may notice while visiting the sea-shore (lower intertidal zone) some flower-like animals. If you touch them they will sink deep into the sand. Sea anemones are tube-like invertebrate sea animals with extended flower-like tentacles spread from the upper side (around the mouth) of the body.
Tentacles are like petals of flower arranged around the mouth opening by one or more whorls. They are sessile attached at the base to the surface beneath it by an adhesive foot (pedal disc). Tentacles of sea anemones contain numerous stringing cells (cnidocytes). They help in self-defence as well as used to capture prey.
3. Sea pen—(Pennatula) –
The sea pen is a colonial invertebrate marine animal of the phylum Cnidaria. They occur in shallow and deep waters from polar seas to the tropics. This graceful creature of the seafloor resembles a pulp, old-fashioned quill pen in colour range from dark orange to yellow to white.
The lower part of the central stalk of the animal (peduncle) anchors the colony in mud or sand and the upper part the rachis bears polyps or branches bearing several polyps (hollow stalks with Sea pen a mouth and tentacles at the free end) Most of the sea pens luminescent or glow when they are touched or otherwise stimulated.
4. Octopus—
Octopus is a rounded soft-bodied marine animal with eight long arms. The soft body can rapidly alter its shape, enabling the octopus to squeeze through small gaps.
Each arm contains many suckers, a mouth at the centre of the arms. Octopus has two big (bulging) eyes. The eyes and brain of octopus are the most developed organ among invertebrates.
Jet Propulsion –
Octopus expelling a jet of water rapidly through siphon into the sea helps them to rapid locomotion. All Octopuses are venomous (poisonous) but only the blue-ringed Octopus are known to be deadly to humans. Octopuses expel a special ink from ink-sac to protect them from predators.
The giant pacific octopus is the largest known octopus species. Octopuses have a relatively short life span some species live for as little as six months. The. giant specific octopus may live as many as five years. Octopus life span is limited by reproduction: males can live only a few months after mating and female die shortly after their egg hatch.
Female octopus guards its fertilized egg in such a way that they do not take any food and die from starvation after the eggs hatch, (due to the inactivation of digestive glands.)
5. Squid and cuttlefish (example Loligo)—
Squids are marine molluscs closely related to octopus and cuttlefish. The body is elongated (torpedo-shaped) there is a fin near the end of its body. Squids are probably the Squid is a good swimmer and the fastest marine invertebrate. Squids is a good swimmers and certain species can fly for short distances out of the water.
The skin contains a pigment (chromatophore) which enables the squid to change- colour to suit its surroundings. The Head-end bears eight short arms and two long arms called tentacles each arm has many suckers along the edge.
When attacked to escape from predators spraying brownish or blackish fluid makes the water turbid to make fool its enemies. The Giant squid lives in the deeper parts of the Atlantic ocean. (50 – 60 feet long).
Cuttlefish (example Sepia)—
Cuttlefish is a close relative of the squids. These marine molluscans have broad bodies with long undulating fin on each side. This animal lives in shallow water on a sandy bottom. They have a sleeper-like calcium-containing internal shell (cuttlebone). You may seen these plenties in the seashore. (This article is sold as sea foam)
6. Shark—
Sharks are marine fish but they have soft more elastic cartilaginous skeletons not hard skeletons like bony fishes. They have usually five-gill slits on either side of head (sometimes seven).
If you put your hands over shakes body you will feel roughness. This is because the skin of a shark is entirely covered by hard microscopic placoid scales (dermal denticles)
The scales are supported by the spine which feel rough when stroked in a backward direction. Sharks have numerous sets of replaceable teeth. If loss one set then replaces by another. ‘Well-known same species are – great white shark, blue shark, hammer-headed shark are predators.
Sharks possess heterocercal caudal fin in which the dorsal portion is usually noticeably larger than the ventral portion. Sharks have keen olfactory senses. Some species are able to detect as little as one part per million of blood in seawater. Sharks have a special sensory organ known as the ampulla of Lorenzini which help them to sense electrical fields in the water.
Some sharks lay their eggs in the water, and most of them are kept in egg case which protects the developing embryo (s). Some sharks (Hammer-heads) give birth to fully functional young like mammals. Sharks are found in all seas. They are usually common down to the depth of 2000 metres (7000 ft) and same live even deeper.
Among 470 species only four have been reported attacks humans these are the great white shark, oceanic white lip shark, tiger and blue shark.
Starfish is a five-armed star-shaped marine echinoderm. Starfishes are not fish they are invertebrates. They are flattened have a central disc from where five arms radiate. The upper surface (aboral side) is granular or spiny. Mouth present in the ventral surface (oral side).
Starfish have tube feet which help In locomotion (moving) and feeding. Tube feet are hollow with sucker work like a vacuum cleaner. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown.
Starfish have a specialised water vascular system made up of a network of fluid-filled canals. This system helps in locomotion, adhesion, food manipulation and gas exchange. Starfish are found in the intertidal zone as well as in the deep sea.
Pollution in the ocean and problem of Marine life :
Oceans are the largest water bodies on the planet. It is the home of a wide variety of marine animals and plants. Over the last few decades, human activities have severely affected the marine life on the earth oceans.
Ocean pollution or marine pollution is the spreading of harmful substances such as oil, plastic industrial and agricultural waste, pesticides, and chemical industrial particles into the ocean.
Any type of ocean water (sea water) contamination which affects living organisms is called marine or ocean pollution. Mining for materials such as copper and gold is a major source of contamination in the ocean.
1. Pollution by sewage, chemical sewage or polluting substances flow through sewage, rivers or drainages directly into the ocean. Chemical fertilizers and pesticides use near by fields are also washed out and mixed with seawater. Excessive nutrients such as nitrates, and phosphates, commonly originate in domestic sewage, runoff from agricultural fertilizers, waste material from animal feedlots, packing plants etc.
They stimulate the growth of microorganisms. The number of phytoplanktons increases enormously consequently they cover the ocean surface. This is called an algal bloom. An increase of dinoflagellates also causes algal bloom.
It turns the seawater red. Toxins secreted from these algal booms also cause the death of many marine animals. Besides this decrease in the transparency of water hampered the penetration of sunlight into the seawater. It also hampered the photosynthesis of sea plants.
The presence of too many planktons and other microorganisms reduces dissolve oxygen (increases biological oxygen demand = BOD ) respiratory activities of marine animals and plants and lead to the death of marine animals.
Oil spills—
An oil spill is an accidental and incidental discharge of petroleum in the ocean. The main source are offshore exploration wells, extraction wells, oil refineries, and the loading and unloading of tankers.
2. Oil spills—
During oil extraction from sea and oil transportation, linkage of tanker ships and during the war, crude oil mix with sea water which causes ocean pollution. Oil form a layer in the upper surface of sea water which prevents oxygen to get dissolved in water. As a result, marine life forms can die due to oxygen deficiency.
Besides this oil form a layer over the body of large sea animals especially birds and mammals. This severely damages the thermostatic balance (body temperature balance) eyes and noses smearing (coating of greasy substances) of sea birds which because incapable of flying and feeding resulting in their death.
Oil when entering inside the body it also damages internal organs. During the Iraq war a large number of sea animals (especially birds and mammals) died due to ocean pollution.
3. Plastics—
Plastic objects float on the sea coming from rivers, canals or from the sea shores or sometimes in harbours and ships. When this object is consumed by sea animals in confusion this large object creates an obstruction which hampers the normal functioning of the alimentary system. The animal can die due to starvation or infection.
4. Increase in acidity of ocean water—
C02 emission in the atmosphere increases due to various human activities. The sea absorbs a large part of this carbon dioxide (C02). This dissolved C02 and increase the acidity of seawater. This affects sea life. Gill-breathe animals face difficulties to absorb oxygen from acidic seawater for their respiration.
Besides this, the animals which have chitinous or calcareous covering shells such as crabs, lobsters, snails, and corals face difficulties in forming their shells and acidic water can destroy the calcareous shell.
5. Thermal pollution—
Various industrial processes may utilize water for cooling and the resultant warmed water has often been discharged into sea in some coastal areas. Coal or oil-fired generators and atomic energy plants generate a large amount of waste heat which is carried away as hot water and caused thermal pollution. Thermal pollution can exert a disruptive effect on coastal marine ecosystems.
A Desert is a very dry area of land often covered with sand or rocks. Where there is very little rainfall (20 cm – 25 cm) and few plants and animals can live. Desert covers approximately one-third of the earth’s surface. The two largest deserts on Earth are in the polar areas Antarctica (5-5 million sq. miles).
The second largest desert is the Arctic polar desert. (5-4 million Sandy desert sq. miles). It extends over parts of Alaska, Canada, Greenland, Iceland, Norway, Sweeden, Finland and Russia.
Non-Polar desert-
The rest Of Earth’s deserts are outside of the polar areas. The largest is the Sahara Desert a subtropical desert in northern Africa (which covers 3-5 million sq. miles) Across the world around 20% of the desert is sandy.
Antarctic deserts and Arctic deserts are cold deserts where these are land covered by ice and another sand cold desert is the Gobi Desert of Asia. Other important deserts are Sahara (Africa) Arabian desert (Middle east), and Kalahari (Africa). In India, the Thar desert covers a major part of Rajasthan.
The days in the desert are extremely hot and the nights are cold. Deserts are characterised by scanty flora and fauna. Only the organisms having specialised structural, physiological and behavioural adaptations to withstand the extremes of temperature and aridity can survive there.
The Equator passes through the middle of the earth. Deserts do not occur near the equator. Higher in the atmosphere the new cold, dry air rises and moves away from the equator.
Nearly one-third of (1/3) earth’s land surface is desert.
There are four different types of deserts based on their geographic situation.
Oasis :
Oasis is an isolated area in the desert with some vegetation, animals and small water sources like a pond or lake. A little bit of rainfall in the desert accumulates in the layer of the rocks found deep. From the deep water comes out when the layers of rock break form’a a pool or small lake.
This is mainly due to the artesian aquifer, water can reach the surface naturally by pressure or by man¬made wells. Surrounding this pond or small lake trees grow. As the trees and a few other plants grow different animals also appear. The number of oases is very limited.
A Desert is an endless stretch of sand with high temperatures and high concentrations of C02. Soil is absent. There is a profound scarcity of water. Yet plants grow in such advanced conditions. Desert succulents such as cacti or rock plants survive dry spells by accumulating moisture in their fleshy tissues.
They have an extensive system of shallow roots to capture soil water rapidly (within a few hours) after it has rained. Roots of many plants grow deep into the soil to collect water, to avoid friction with sand root caps become strong.
In addition to these many cacti and other stem-succulent plants of hot deserts grow vertically and usually leafless green trunks (stem) that use sunlight of the early and late hours of the day. Many plants have no leaves and leaves turn into thorns to check evaporation.
The number of stomata in leaves are less. Plant body covered by cuticle to prevent evaporation. Some plants come out after little rain and survive very few days but within this short life span, they produce flowers and seeds. In some cases, seeds lie dormant stage and wait for a favourable environment or conditions.
There are other long plants that can survive for long period without water.
Cactus-
Ordinary cactus or prickly pear is found in most of the deserts of the world. No animal or bird can .eat them as they are covered by thorns. Thorns are their protective organ as well as prevent evaporation of water. Their stems are green and able to make their own food by the process of photosynthesis.
Saguaro Cactus-
A type of tall tree like giant cactus having branches can grow up to 50 feet (12.2 metres). Its life span is about 150 to 200 years (usually found in the Arizona desert, Mexico) A saguaro cactus is able to absorb and store a considerable amount of rainwater (six to eight tons of) water is their body.
They use this stored water as needed. So they are able to survive during periods of drought. The body of this cactus is covered by long thorns. Flowers are whitish to yellow in colour and open well after sunset. Fruits are edible ruby red and contain many seeds (about 2000).
The desert travellers quench their thirst with this plant. They collect water by cutting their expanded trunk. The fruit are used to make Jam. Woods are used to making strong ropes and building houses.
Joshua Plant –
A type of succulent plant that they store water. They grow about fifteen to forty feet long. They are considered trees of the desert. Their life span is about 200 years. This plant usually have a single trunk and grows three to nine feet tall before branching.
Joshua trees are fast growers of the desert. Branches end with dusters of spiky leaves and white rounded flowers. A number of mammals rely on Joshua trees for food. Jashua plants have very thin leaves therefore less water is evaporated.
They have a special and extensive root system. They have special root systems so they can soak up a lot of water. Man use the leave of these trees as plates and bowls.
Mesquite plant-
These are leguminous desert plants with long roots. They grow up to 8 metres. They have one or multiple trunks with bipinnate leaflets. They can store water but they have long tap root which can reach below upto the rock layer. They collect water from that rock layer. They protect the sand dunes of the desert.
Cactus as food-
Cactus is a very important as well as useful plant for the desert people. Food is stored in the roots of the cactus. For this roots become very large and thick. Desert people are able to recognise this root part. The fruits of the saguaro cactus look like a watermelon.
Write down the adaptations of desert plants in tabular form and the purpose of that change :
| Desert plants | Adaptation | Purpose |
| 1 | ||
| 2 | ||
| 3 |
The environmental conditions of the desert are not so favourable like other environments. Desert animals get radiated heat of the sun. The heat also enters their body from the soil and rock through the conduction process and from air through the convection process. In addition to high temperatures, they face scarcity of water.
But the desert animals adopted themselves with the condition. Some animals like camel have suited them well with the surrounding condition. In the sandy desert, there is terrible heat during the daytime and there is cold in night two extreme conditions. Usually, desert animals remain to stay in their den (dig burrows in the sand) and come out in the evening.
They are nocturnal in habit. Some animals are active for a few hours only during the early morning. Most of desert animals are small in size. A desert, lizard (Moloch) can absorb water through its moisture-absorbing (hygroscopic) skin.
Camel-
The camel is an excellent example of adaptation to desert life. Camel is known as the ship of the desert. Two types of a camel on the basis of the hump. One-humped (Arabian camel) and two-humped (Bactrian camel).
Important Adaptation of camel :
Observation :
Different body parts of camel and their structural peculiarities :
| Body parts | Structural peculiarities |
| 1. Legs | |
| 2. Snout | |
| 3. Eyes | |
| 4. Lips | |
| 5. hump |
There are different types of lizards in desert. Most of them come out during the evening or night in search of their food. They store fat in the tissues of their wide tail. Many desert lizards have the ability to adjust colour- due to temperature (this is known as metachromatism)
They cannot regulate their temperature internally so they rely on their environment to keep the temperature in the correct range. When the temperature cools, lizards turn darker. Dark colours increase heat absorption when desert temperatures rise their colour became lighter, which reflects the heat and keeps the lizards cooler.
Their eyelids are covered with transparent membranes. They are usually insect feeders.
Rattlesnake-
Rattlesnake is one of the most poisonous snakes of the desert. They have a hollow rattle at the end of the tails. This rattle makes a loud rattling noise when vibrating. Their body colours very much similar that of their surrounding’s sand colour. They have two hollow fangs, Rattle snakes consume mice, rats, small birds and other small animals.
The prey is killed quickly with venomous bits. Eyes and a set of heat-sensing pits on their face enable rattlesnakes to locate prey and move towards. Rattlesnakes are cold-blooded animals and can swim well over sandy surfaces. Rattle shakes have an exceptionally keen sense of smell.
They can sense olfactory stimuli both through their nostrils and by flicking their tongue. Rattle snake’s skin has a set of overlapping scales which cover the entire body providing protection. They are nocturnal. Their main predators are eagles, hawks, owls, king snakes etc.
Gerbil or sand rat—
Gerbil is a small mouse-like rodent specially adapted to living in dry desert conditions. This nocturnal animal lives inside the burrow by digging in the sand. They can jump like kangaroos therefore Gerbil is known as a kangaroo rat. They have a long tails.
Their body colour is white to brown they can change their body colour with the sand. This device is for protecting themselves from enemies. They are nocturnal and eat seeds and small grass, small crops, fruits, and small insects and can live with their whole life without taking water. Their ears are very active.
Animals of Thor—
The Thor, the great Indian desert has an unmatched variety of fauna. Indian wild Ass is one the endangered species of Rann of Kutch. Some other native species of the Thar desert include the desert scorpion, the red fox, the blackbuck, the Indian Bustard, the wild cat etc.
The Indian spotted eagle is one of the biggest flying predators and threatened species found in Thar. The Great Indian Bustard is among the heaviest flying birds in India found in the Thar desert. The Indian national bird peacock is also found here.
The Blackbuck (Antilope cericapra) is one of the most famous antelope natives to this desert. They are dark brown in colour and have a white circle around the eyes. blackbuck male antipode has beautiful twisted-ringed horns. Kites, doves, sand hens and some other birds are also found there.
Make list of desert animals and their characteristics and adaptations.
| Name of the Desert animals | Specialization for Desert condition |
| 1. | |
| 2. | |
| 3. |
Though more or less extreme climatic conditions prevail in deserts. Vet people live in different deserts since prehistoric times. Every group of people has some speciality. The Thar desert is the most densely populated desert in the world. The notable desert dweller groups are Wardha, Bhil, Gadi-Lohar etc.
The main occupation of the people of their desert is animal husbandry. A colourful culture rich in tradition prevails in these desert dwellers. The Bedouins a historically popular group of people inhabited the Sahara and Arabian desert. They wear a long loose dress which covers their whole body that protects them from sun and heat.
They are traditionally divided into tribes and share a common culture of herding camels and goats. Bedouins are nomads (have no fixed location) who move from one place to another. They travel mile after mile on a camel at stretch for several days, take a rest in tent for a few days and start again travelling.
The Himba people live primarily in the northwest region of Namibia. The Himba people cover their bodies with red ochre and animal fat to protect their skin from the powerful sun. The Himba men and women are recognised around the world for their colourful ornate jewellery and dress.
In the desert of Namib (present in Namibia) live a special ancient group of people is Cushman. They dig holes in the sand and live there. They are a good hunter group. They use bow and arrow. After hunting they eat that animal by roasting it. The people live in the Kalahari desert is known as San Bushman.
They dig and make a hole in wet sand and suck water from land by a long strong hollow grass stem. These people use empty Ostrich egg shells as waterpots. They have a special ability. They can easily understand whether water is present in that sand or not by seeing the design of the sand.
Tuareg, the large tribal people live in the Sahara desert (from Libya to Southern Algeria). They make hut with a special type of grass found in the desert. The Red Indians of American deserts live together. They build their house together. Every house as a good number of rooms. These stone-made houses are called Pueblo.
Animal world in the Polar region:
Polar regions are the geographical areas place surrounding the north and south poles of the earth. The Polar regions are the coldest place on the earth, hardly seeing the sun during the winter and having 24 hours a day in the summer.
Two polar region-Arctic is the area surrounding the North pole and Antarctica is encircling the south pole. The arctic region includes almost the entire Arctic Ocean and the northern parts of America (Alaska) Canada and Europe (Denmark, Norway, Finland, Sweden, Iceland, Russia) and parts of Asia.
Antarctica includes the continent of Antarctica and the parts of the surrounding Southern Ocean.
The temperature in the polar region varies for- 88°C to 15°C. Living in polar regions are very difficult. Though a rich diversity of wildlife— both on land and under the sea surface. Millions of people also live in the Arctic but Antarctica has no permanent inhabitants.
In the Arctic region, a good number of mammals are found. They are mainly Seal, Sea lions, Whole, Caribou, dogs, dolphins, etc. Wolves are the top predators of the Arctic tundra and polar bears dominate the frozen waters, deeper in the sea Seals, Sea lions, walruses, and killer whales are common in this region and usually feed on the fish.
The animals are usually found are the Arctic fox, Walrus, Seal, snow owl, and white hair. Penguins are the most abundant and best-known animal of Antarctica. Besides this whales, seals, and sea birds (Albatron). Antarctic krill (small crustaceous) are important animals in Antarctic food chains.
How the animals able to adjust themselves within the polar condition?
Migration is the mass movement of animals from one geographical region to another. Many animals of the Arctic region like birds, fish, Reindeer etc. migrate from colder regions to warmer places to find food, to lay eggs or give birth to their young ones.
For example-
The Arctic Tern (Sterna paradisiacal) a small seabird that cover a distance of around 40,000 to 90,000 km in each year. The Arctic Term breeds in the Arctic before making its way to the Antarctic (winter is spent here). It is probably the longest migration undertaken by any bird.
How the Animals (mammals) of polar regions stay warm?
The Arctic is very cold. Warm-blooded animals are usually found there. Now the question how do the Arctic animals stay warm in ice water and cold land area? Due to global warming ice packs of poles melt rapidly and if the condition prevails. The polar bear will not survive.
Animals like Walruses, Seals and Polar bears all have a thick layer of fat (in the case of a Polar bear 4 inches wide) called blubber that keeps them warm in the ice-cold water of the Arctic and Antarctic. Polar bears have black skin underneath two layers of fur that help trap the heat when they are on land.
They have small ears and large paws. The fore paws of the polar bear are partially webbed which assists them in swimming. Their eyes are well adapted to see things underwater. Their sense of smell is highly sensitive and helps them to detect food sources (32 km away). This helps them to predate upon their prey.
Penguins are distinctive flightless birds of Antarctica. Their wings have evolved into flippers which they use to swim through the thick water in pursuit of krill fish and others.
Inhabiting the ice and sea of the Arctic Polar Dears arc well equipped for survival in harsh environments, TVvo coats of fur and a thick layer of blubber help them to insulate their body from the cold. Polar bears’ skin is black which helps them to hold the maximum possible heat and the fur (hair) is not actually white it is actually transparent mostly hollow air-filled and holds no colour.
If only appear white because it reflects visible light. The white fur helps polar bears to camouflage in the ice and snow. This helps them to predate upon their prey. Polar bears have a layer of fat under skin that can be 10 cm (4 inches) thick.
Although their fur is the prim a 17 source of insulation, the fat helps keep heat in as well. The fats of polar bears also help to stay in the water. Polar bears are our planet’s largest land predators and are highly dependent on older stable pack ice in the Arctic region.
The habitat of the polar bear are shrinking day by day due to global warming. Global warming is the main cause of ice melting. People are the primary enemy of polar bears they have been hunted over time for fur, skin and nails.
Hibernation :
Hibernation is a behavioural adaptation that allows animals to survive during the winter months. Many terrestrial animals of the Arctic region go through hibernation at the beginning of winter. Small ears and short tails offer less open (furless) surfaces helping the polar bear to maintain body warmth.
How do arctic animals lay eggs or give birth to their young ones?
Most of the Arctic animals abstain from giving birth to young during the intense cold. Usually, they lay eggs or give birth to young during the short summer when vegetations also grow for short period. A female polar bear normally gives birth to 2 cubs, (it may one to four) during January in the den she built to keep them safe.
Where they can grow big and strong until spring. The cubs feed on their mother’s milk during this time. Dens are normally dug by the mother’s front and hind paws in snow drifts.
After about 3 or 4 months polar bear cubs venture outside the den with their mother. There are more than 250 types of fishes are found in the arctic ocean common of them are—Salmon, codfish, Halibut, etc. To survive in the cold, polar fishes have evolved suitable physiological and biochemical mechanisms.
Freshwater habitats exist in the Arctic but are more limited in Antarctica. During winter months the atmospheric temperature is very low it drops below freezing and the upper layers of water in the lakes and ponds freeze in 0°C while the lower part still remains at 4°C (water is heavier at 4°C, density) of water is high of this temperature so the lower water remains liquid and ice floats on top fishes and some other aquatic animals remain in this liquid layer.
There are other dangers that fish face in freezing waters like death. The body fluid of an ordinary fish can solidify if the temperature of the surrounding water drops below – 5°C. So Arctic and Antarctic fish have adjusted to their surroundings in an interesting manner.
Certain species of cod, flatfish and polar fish have reduced metabolic rates and’ produce antifreeze molecules (glycoprotein) to reduce the freezing point of their body fluid. The enzymes of arctic fishes are able to carry out chemical reactions at low temperatures.
Polar fishes have a much slower metabolism. Thus they utilize less food for energy production so they do not need much food to survive.
Animat variety is more in the Arctic region—Why?
The Arctic has a wider variety of animal life than Antarctica. The North pole is in the middle of the Arctic Ocean which is surrounded by the land masses of North America Europe and Asia. So there is a land connection. Therefore, Land animals can more easily reach the Arctic whereas in Antarctica animals have to cross hundreds of miles of frigid and storm-prone ocean, more than ever.
Animals must be able to swim or fly. The animals of the north polar region can be seasonal visitors. For this reason, animal variety is more in the Arctic than in Antarctica.
People of the Arctic region— The people who settle permanently in the Arctic Polar region are popularly known as ‘Eskimo’.
The Eskimo are the indigenous peoples who have traditionally inhabited the northern circumpolar region from eastern Siberia (Russia) across Alaska (USA), Canada and Greenland. Their ancestors crossed a land bridge and reached this land from Asia which no longer exists today.
They traditionally lived by hunting (specially seal) and by fishing. The term ‘Eskimo’ means the people who eat raw meat. Linguists now believe that ‘Eskimo’ is derived from an Ojibura word meaning ‘to net snowshoes’. However, the people of Canada and Greenland prefer another name ‘Inuit’ meaning ‘indigenous people’.
The Eskimo (= Inuit) make their clothes of animal skin. They wear two layers of clothes of Caribou skin. The inner Eskimo layer of fur is against the skin and the outer layer of fur faces out. They also made clothing from other animal skins including dog, squirrel, marmot, fox, wolf, polar bear, bird skin, feathers and seal skin.
Eskimos (Inuits) during summer (when the snow melts) prepare their home made out of Cartoon or Seal skin hung off a frame made of driftwood or whale rib bones. They lived in Igldos the snow house (= snow hut) in the winter. The Igloo was made from hard-packed snow.
They used knives made of bone (now they also use steel) to cut snow blocks (Nowadays Inuit culture has been changed a lot most Inuit people today live in the same community year-round, and live in homes built of other construction materials, that have to be imported).
There are three traditional types of Igloos all of different sizes and used for different purposes.
Why structure of igloos or tents not made up of wood?
Because there is no trees in the arctic tundra area.
Food :
Eskimos live in such places where hardly few plants can grow. The traditional diet consists of almost entirely meat and fish. They get their food by fishing and hunting. Whales, Walruses, Seals, and fish like Salmons and Cod are the main food.
They also hunt and eat the flesh of ducks, Hares, Polar foxes, and Polar bear. Dogs are indispensable in the life of Eskimos. They use dogs during hunting, pulling Sledge Cars, and also use the smelling power of dogs to identify the hunting animals.
The earth’s north and south poles are known as the end poles lying to the extreme points of the earth. The north pole is the Arctic region which is located in the middle of the Arctic Ocean surrounded by continents on the other hand, South pole comprises of the huge Antarctic continent (ice-covered land) surrounded by oceans.
In the South pole (Antarctica) Seals, Whales and Dolphins are around with Penguins but Polar bears are absent here. Penguin is not found in the north pole but polar Bear is found there.
Different types of Penguins are found in Antarctica but among them, the Emperor Penguin is the most remarkable. The Emperor Penguin is the tallest and heaviest of all living Penguins species and is endemic (only found in that place) to Antarctica.
They can live both in ice and water. Its diet consists of fish, krill (small crustaceans) squid. In hunting, they can remain submerged up to 18 minutes and drive to a depth of 535 m (1,755 ft).
Penguins have some special adaptations such as unusually structured haemoglobin allows them to function at low oxygen levels, solid bones to reduce barotrauma (tissue damage due to pressure) ability to reduce metabolism and able to shut down non-essential organ functions.
The female penguin lays one egg (460 – 470 gm) during May and early June during peak winter when darkness and chilling cold descend on Antarctica (Breeding season April to December), After laying the egg the mother’s nutritional reserves are exhausted and she very carefully transfers the egg to the male and returns to the sea for two months to feed.
The male incubates the egg in his brood pouch, balancing it on the tops of his feet. The incubation period last for two months (64 days), [The emperor penguin is the only species where this behavioural peculiarity is observed in all other penguin species both parents take shifts incubating,]
By the time the egg hatches the male will have fasted for a long time (usually not taking any food) (around 115 days). To survive the cold and winds the males huddle together, After hatching (it takes 2-3 days as the egg cells arc very hard) if not the mother rot urn the father penguin feed- the chick a curd-like substance (composed of protein and fat, produce in the oesophagus).
[This ability to produce milk in birds is only found in regions, flamingoes and male Emperor Penguin.] The female Penguin returns of any time after hatching and take care of the chick. The male then go to sea. Both parents take care of the chick. Alternately they doing this unless and until the chick is independently able to hunt (during summer).
The Crisis of Penguin-This unique creature of Antarctica faces serious throats mainly from human activities like overfishing creating their food crisis,use of plastics by explores cause serious damage (sometimes they eat it as food), They are killed for their fat. oil for manufacturing soaps, and fuels.
Penguin feathers for making dresses, shoes, bags etc. To protect these creature International Ornithological Congress urged different nations to protect penguins. In 1959, 12 nations agreed to sign the Antarctica Treaty, This treaty ensured the protection of the Penguin in Antarctica.
Antarctica is one of the cleanest and least polluted places in the earth, It is the ideal location for measuring the spread of global pollutants. Minute traces of man-made chemicals used in other parts of the world can be detected in the snow that falls over the region.
Some facts of Antarctica :
Chlorofluorocarbons (CFCs) and halons are used indiscriminately by human beings for different purposes have reduced the thickness of the ozone layer present over the Antarctica region. For this reason, an ozone hole has been created. Harmful UV (Ultraviolet rays) penetrate the atmosphere of the earth through these holes.
UV radiation can harm humans as well as other organisms by causing skin cancer (man), and cataracts and decreasing the number of different micro organisms living in water that affect the water ecosystem. Increased shipping activities in Antarctica oil-spill, building materials rubbish, metal items, oil and other fuels and plastics in a variety of places in Antarctica also cause hazards.
Birds and seals often engulf some pollutants (plastic, metal, rubbish etc.) leading them to death.
Identify the causes of pollution and how they can be controlled.
| Pollution type | Cause of pollution | Effect of these – pollution | Controlling measure |
| 1. | |||
| 2. | |||
| 3. |
Conservation Of Wild Life
We have already seen that human life and its growth depends on different plants and animals in various ways such as food, shelter, fuel, clothes medicine, commercial goods etc. But increasing human population damage biodiversity in many ways- wildlife is being affected seriously.
Environment
The environment is the surroundings in which animals and plants live. Environment influences the life of organisms in many ways.
Habitat
Habitat is the special environment of an organism in which it lives and grows.
This is necessary for the conservation of the habitat of human resources for the existence of human beings as well as its surroundings. Wildlife is important as because it balances the population, maintains the food chain, and natural cycles, and biodiversity controls pollution and prevents soil erosion.
Biodiversity degeneration is a serious threat to human existence. Due to human activity and natural calamities, many animals and plants already extinct some are in the verge of extinction.
The international agency IUCN (International Union for Conservation of Nature and Natural Resources) has published the list of names of endangered animals. The name of this list is called Red Data Book.
In this list different animals have been placed (categorised) at different called levels.
Some endangered animals of India are :
How can Endangered Animals be saved?
Various methods have been taken to save endangered animals in different places of the world. All these methods of saving endangered species are now altogether referred to as a “Gene Bank”.
In-situ conscrvation-
When endangered animals and plants are conserved in their natural habitats such as natural ecosystems or man-made ecosystems. This involves the protection of natural habitats and maintenance of endangered and other important species by certain protected areas such as national parks, wildlife (natural habitat) or bird sanctuaries and biosphere reserve.
Ex-situ cohservation-
When some animals cannot be conserved in their natural habitat then attempts have been taken to conserve these animals in some distant places like Zoological and Botanical gardens away from their natural habitat by creating favourable conditions.
Besides this microbes, seeds, tissue, cells and genes of plants are also conserved in laboratories (cryo-conservation) from their natural habitat by creating the favourable conditions.
Vulture :
Vultures are large-sized birds. They feed on dead and decaying animals. They are also known as birds of prey. They have a good sense of smell and sight. Vultures have very strong. bills and claws. The colour of their body is dark brown and they have a slender curved throats without feathers.
They push their elongated throat into the carcasses of dead animals and collect food. Feeding on the carcasses they help to keep our villages and cities clean and hygienic. Shelter—Vulture builds their nests high on the branches of Banyan (Bath), Peepal, Rain- tree, Palmyra, Tamarind, Silk cotton and some species of Fig trees.
The nest made up of dry twigs and branches are strongly built. Their breeding period is in between September to March. Vulture lays a single egg.
Vanishing Vultures (Vulture crisis) :
India has lost more than 97% of its vulture population in the last about 12 years. Due to this decline, vulture species were listed by IUCN as critically endangered. In 2002 it was also placed in schedule I of the Wild Life Act. According to some experts, the lethal level of the drug Diclofenac is the main cause.
Diclofenac is used as a painkiller for treating animals. It enters the bodies of vultures when they feed upon it. diclofenac—Contaminated carcasses. Vultures are highly susceptible to it. These in their bodies cause gout dehydration and kidney failure and eventually death.
Death may be due to infection of the virus (new strain). Vultures are one of the main causes of aircraft accidents. The increase in air traffic may be one of the reasons for the decline of vultures near aerodromes. Vultures are dying at an alarming rate.
Being keystone species, the decline or extinction of vultures will adversely affect other wildlife, domestic animals and humans too. It can also increase the risk of (epidermic) diseases due to the non-disposal of carcasses etc. Bold and intelligent steps are required to be taken to conserve these wonder fliers and scavengers.
Conservation of Vultures—
The attempt to conserve Vulture has been initiated. India’s Government has banned the use of Diclofenac since March 2006. Several vulture rehabilitation centres were set up in different parts of India. The two most significant such centres are Pinjar of Haryana and Rajabhatakhawa of North Bengal.
The life span of a vulture is long and the rate of growth is very slow. Therefore, the recovery process needs much time. Now all species of vulture are being conserved under the strict vigilance of the Wild Life Conservation Act.
The fishing cat Is a medium-sized wild cat of 5outh and South East Asia. Through the distribution of these animals world-wide and have great adaptive abilities. Since 2016 it is listed as vulnerable on the IUCN Red list. Fishing cats are popularly known in Bengal is ‘Baghrole’.
Fishing cat populations are threatened by the destruction of wetlands and declined severely over the last decade.
Fishing cat —Behaviour, habitat and structure :
Fishing cats are usually nocturnal. They are very much at home in the water and can swim long distances even underwater. Birds, insects, small rodents, molluscs, reptiles, and snakes are their main diet. Fishing cats is larger than a domestic cat.
They have a deep-chested body with short legs and big broad heads and short tails. Fishing cat (Baghroie) There are elongated dark brown spots arranged in longitudinal rows extending over the entire body. There are six to eight dark lines running from the forehead to the neck and the underparts are whitish and spotted.
The fishing cat is well adapted to catching fish, their front feet are partially webbed and their claws are incompletely sheathed so that they protrude slightly when reacted.
Crisis and conservation of Fishing cats:
Fishing cats are widely distributed but concentrated primarily in wetland habitats, which are increasingly being settled degraded and converted. They are typically found in a number of water habitats, mangrove swamps and densely vegetated areas along rivers and streams.
The habitat and source of natural food of fishing cats are decreasing day by day. So nowadays they are being compelled to intrude into human habitat in search of ducks and hens.
They are also being killed by humans. If we fail to keep their natural habitat and food products these animals will extinct in near future.
Habits, Habitat and structure o? Gangetic Dolphin. The Gangetic Dolphin is a freshwater aquatic mammal that lives in the river Ganges Ganga and Brahmaputra river and their tributaries. The Ganga river Dolphin or Susu lives in one of the most densely populated regions on the world.
One of the main threats to the species is loss of habitat due to a large part to the river loss by the creation of dams and irrigation projects. The Ganges river Dolphin has been recognised by the Government of India as Its Nationa Aquatic Animal.
Gangetic Dolphin can be easily identified by their long thin snout (rostrum) (long pointed nose) with visible teeth in both the upper and lower jaws even when the mouth is closed, rounded belly, steam line body and two front legs are modified into large flippers, the tail is flattened dorso-vcntrally (top and bottom).
The colour of the Dolphin is greyish-brown or deep black in colour. The middle parts of the body is thick and two ends are pointed. Their skin is hairless. A layer of fat (blubber) under their skin, keeps their body warm even under water.
The two lips in front of the mouth are protruded like a beak. In each jaw there are 27 — 32 small similar teeth, (There is no varieties of teeth) Nasal orifice is elongated and situated at the tip of the beak. They can open or close this orifice as their will. Although they are aquatic they inhale aerial oxygen by coming to the surface of the water.
The head and the body cannot be separately distinguished due to the absence of a neck. They do not have an eye lens (crystalline lens) that blinds the dolphin yet they are able to detect the intensity and direction of light.
Dolphin has a strong sense of smell.
The dolphin has the peculiarity of swimming on one side so that its flipper trails the muddy bottom this behaviour is understood to help it to the food.
Navigation
Navigation(feeling the direction) and hunting are carried out using echolocation. The animal emits some sounds with the help of organs namely the dorsal bursa present in the nasal cavity. That travel and return after getting obstructed by any object.
Dolphins understand what lies ahead from far it is by hearing the echo. The Gangetic Dolphins are carnivorous. They hunt the animal that hides in the muddy bottom of the river by echolocation.
Fish and different aquatic invertebrates like prawns are their food. After detecting their prey they use the long snout (rostrum) to get hold of the prey.
The crisis and conservation of Gangetic Dolphins:
Excessive contamination in Ganga is a serious threat to the survival of aquatic life there. The increasing level of industrial effluents sewage and pesticides are causing harm to the critically endangered, Gangetic dolphin.
Shortage of small aquatic animals like fish and other invertebrates causes a food crisis of dolphins. The depth of water in the river is decreasing due to the construction of dams and other reasons. Communication between different groups of dolphins are lost.
Small and segregated dolphin groups face breeding problems. Sometimes they die being entrapped in fishing nets. Vikramshila Gangetic Dolphin Sanctuary has been set in 1991 in Bhagalpur, Bihar. It is a protected area for the endangered Gangatic Dolphins in Asia. ‘
An awareness campaign for Dolphin conservation has been started among the fishermen. WWF-India also had started the Dolphin conservation programme to conserve the habitat of the Ganges River Dolphin and secure a future for this endangered species.
Habit, Habitata ahd Structure
The Indian Rhinoceros (Rhinoceros unicorns) is also called the greater one-horned Rhinoceros or Great Indian Rhinoceros. This species of Rhinoceros is native to the Indian subcontinent. Now it is found only in the forests of Assam and North Bengal. This is one of the critically endangered animals of the world.
The Indian Rhinoceros once ranged through out the entire stretch of the Indo-Gangetic plain but excessive hunting and agricultural development and new human habitation reduce their range drastically.
Structure :
The Indian Rhinoceros has thick (same places 4 cm thick) grey-brown hard skin with pinkish skin folds and a black horn. The body is hairless except on the tip of nails, horn around the ears and on eyelids. Its upper legs and shoulders and in front of the thigh have hard covering like armours.
There is a thick layer of fat (2 – 3 cm) below the skin. The external ears of the Rhinoceros is roundish and spread. At the side of their body above skin, they have big tubercles.
The Rhino’s single horn is present in both males and females (about 60 cm long) but not in newborn young. The horn is made up of pure keratin, Its a protein, and nail and hairs are also made up of this protein. Horn appears to show after about six years. If the horn breaks for any reason, it regenerates.
The Rhinoceros uses its horn to search for food like digging the soil or finding out the roots of trees. Apart from this they use the horn to fight other male rhinos during the breeding season. They live mainly in the Jungle of tall grasses near flooded plains or wetlands. Rhinoceros usually lives alone with the exception of breeding pair.
They usually move around mostly during early morning, dusk or at night. They take rest in the shade of trees when sun is in high. Rhino is second in size among terrestrial land mammals after elephants. They usually covered their bodies with mud which helps to make the body cool.
This mud coating also protects the body from different insects and parasites. Anthrax is a bacterial disease which usually affected Rhino. Rhinoceros are basically herbivorous. They feed on tall grass or aquatic plants and even fruits.
The adult rhino urinates up to 3-4 metres backwards when irritated. The incisor in the lower jaw is very long. The Indian Rhinoceros has the curious habit of defecating at the same place. Since the defecate at the same place, the dunghill grows in height.
After reaching a height they create a new dunghill. The hunter or preacher of Rhinoceros waits near dunghill because of the habit of Rhino.
Crises and Conservation of Rhino :
Rhinos are facing a severe crisis and unless something dramatic is done to protect them they will go extinct in the wild. In June 2014 the first successful live birth from an artificially inseminated rhino took place.
Once the Rhinoceros spread over the entire Eastern region of the Indian sub-continent now restricted to one or two pockets. The life span of a Rhinoceros is 35-45 years.
This is due to the loss of their habitat and they fall prey to the greed of poachers due to a wrong belief that the horn of rhinoceros has medicinal or stimulating properties. These beliefs do have not any scientific proof.
Presently single horn rhinos can only be seen in the Indian subcontinent in the Brahmaputra basin in Assam (Kaziranga, Manas etc.) two national parks of West Bengal (Jaldapara and Gorumara) Dudhwa reserve forest (Up)(Rhinoceros reintroduce in 1984) and also in Chitwan National Park of Nepal.
Have you noticed yourself and your friends and relatives of your age or one or two years elder in school, family and neighbourhood? After a few days of observation, you will notice some behavioural, physical and mental changes of these people.
If you note down the changes then you will find some physical changes like increasing height, and weight, change of voice [harsh voice (in boys) or shrill in girls] appearance of a thin line of moustache in boys and breast development and the onset of the menstrual cycle in girls, also a change of smoothness of the skin.
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You will also find some behavioural changes among your classmates too. They are more aggressive and try to establish himself or themselves in every event happening around them, getting angry, feeling jealous, feeling offended. Girls will also experience some physiological changes like the onset of the menstrual cycle.
Around us you may notice some short-height (dwarf) and long or very long-height (gigantic) person. If you go to a tea stall you will see some people are asking for tea without sugar and someone taking tea with sugar.
All these events mentioned above are controlled by some chemical substance of the body. This chemical substance is known as a hormone and the system that controls all these are known as the Endocrine system.
Your observation (in two-six months intervals)
| Sex Male/ Female | Age | Height | Weight | Change of nature of behaviour |
| 1 | ||||
| 2 | ||||
| 3 |
Hormone
The hormone is a chemical substance secreted by the endocrine glands (ductless glands) transported through blood (in most of animals) to the site of action, the target cell or organ and regulates the biological processes in the organism and destroys after a function.
Properties of hormone
Co-Ordination
Coordination is the working together of various organs of the body in a proper manner to stimuli. In our body, two types of coordination occur. One control by. nervous system (Physical coordinator) and other by the endocrine system. When mosquitoes or any other insect-like cockroaches etc.
come contract with our skin through merve brain receives the signal and then brain reacts.—Order the hand to remove them. This is an example of Nervous-co-ordination.
The endocrine system is a chemical coordination system in the body. It comprising of endocrine glands, their hormones and their mode of action. It is directly or indirectly under the control of the nervous system. Therefore, the .nervous system and endocrine system are often collectively called on neuroendocrine systems.
After getting the necessary order the hormone is produced in its proper position (endocrine glands) and reaches to the target organ via blood or body fluid. The target here is called the receptor. Hormones in most cases start its work slowly but its effect persists for a long time.
Hormone 4 is destroyed after the completion of work excess or deficiency of hormone levels in the blood or particular parts of the body lead to many disorders.
The human body possesses different types of glands.
The gland is a cell or a group of cells which secret or release specific substances such as endocrine glands secrete hormones, and digestive glands secrete enzymes.
Glands in our body are of two types-
Exocrine glands have ducts and endocrine glands are ductless.
1. Endocrine glands:
Glands which have no ducts (ductless) and pass their secretion into the surrounding blood for transport to the site of action e.g. pituitary gland, thyroid gland etc.
2. Exocrine glands :
Glands which have ducts and release secretion out through ducts, for example, the Salivary gland, Sweat glands. ‘
There are some glands which are both endocrine and exocrine in nature, these glands are called mixed glands. Such as the pancreas secrets enzymes present in pancreatic juice through ducts and the endocrine because they secrete some other hormones directly into the bloodstream.
1. Pituitary gland :
It is a small two-lobed gland found in the base (hypothalamus) of the brain (forebrain). The upper and lower part of the gland is known as the Anterior pituitary and posterior pituitary respectively.
A hormone secreted from Anterior Pituitary glands are –
Thyroid
It is the largest endocrine glands human body. It lies below the larynx on each side and anterior to the trachea. It also has two lobbed glands. The hormone secretes from this gland is Thyroxine. Iodine is needed for the formation of this hormone.
Thyroxine regulates the basal metabolic rate (BMR) and calcium balance of the body. It Enlarged thyroid gland controls the respiration rate and energy production of cells, increases heart rate, also helps in growth by increasing muscle and bone and also develops mental faculties.
Hyperthyroidism-
It is the condition caused due to high secretion of thyroxine and leads to theJSraves’ disease or an exophthalmic goitre (enlarged eyes), enlargement of the thyroid gland which may cause a bulge in the neck (goitre). You may see it in some people’s necks.
Hypothyroidism:
It is caused due to decreased secretion of thyroxine and leads to the diseases-Critinism retardation of physical and mental development in infants and children.
Criticism-
Is a condition produced in infants and children where retardation of physical and mental development occurs? The abdomen becomes swollen, the tongue hangs out.
Goitre enlargement of the thyroid gland— causes when the dietary Iodine intake falls below normal, and thyroid hormone synthesis is inadequate. Myxedema (= Gull’s disease) developed in middle-aged persons. Symptoms loss of energy and appetite, weight gain, mental dullness and dry, puffy skin
Pancreatic Gland
This gland is a mixed gland which are partly endocrine and partly exocrine in function.
location Of Pancreatic Gland :
It is the second largest gland in the body located below the stomach in the loop (V turn) of the duodenum. Endocrine [Darts of the pancreas is called islets of Langerhans [discovered by Langerhans (1869)] Main hormone secret from isolates of Langerhans of the pancreas is insulin, (This gland also secrets glucagon and somatostatin hormone).
Insulin is secreted from the Beta cells of islets of Langerhans of the pancreas. In diabetes Mellitus beta cells (\)) of Islets of Langerhans are unable to produce adequate Insulin, ns a result the movement of glucose ‘ from blood to the cell is hampered, Some of the glucose Is excreted In the urine, as well as loss ‘ of water also caused due to excessive urination. This causes excessive thirst (it s one of the symptoms of this disorder).
A common symptoms of diabetes Mellitus-
In diabetes, a Mellitus person becomes very weak. The functional power of the kidneys, heart and eyes is reduced.
Adrenal Gland
Adrenal glands (= supra renal gland) are paired triangular glands present on the top (upper part) of the kidney, Adrenal glands look like caps set on the kidney, v Adrenal has two distinct parts Adrenal cortex and the Adrenal medulla.
Adrenaline (= epinephrine)hormone is secreted from the Adrenal medulla. Adrenaline helps to combat different emergency situations. So this hormone is termed as an emergency hormone.
Important functions of Adrenaline are
Heartbeat—
Pulsation of the heart including one complete systole and diastole. Contraction of the heart is known as systole and expansion of the heart is known as diastole. It controls urine production. It also controls different mental conditions like fear, conflict, anger etc. Increases respiratory rate.
Hypersecretion of adrenaline the face becomes rounded and swollen this is known as Moon’s face. The skin of the face becomes rougher and more pale. Due to hypo secretion the healing of wounds, hypo delayed, poor digestion and weakness in the muscle.
In general, adrenaline prepares the body to face emergency conditions of physical and emotional stress, like a fall in blood pressure, muscular exertion, pain, cold, injury, anger, fear tension etc. So this hormone is called an Emergency hormone. The adrenaline hormone is known as the fight or flight response hormone.
Gonads-
The gonads are the sex glands of the body such as the ovary and testis these reproductive glands ovary and testis produce ova and sperms respectively. These glands also secret hormones. Estrogen, progesterone and testosterone are called sex hormones. These hormones became active after a specific age in males and females.
Ovary :
Present in the female body. The important hormones secret from the ovary are oestrogen and progesterone.
Testis :
The reproductive gland is present in males. The important hormone secreted from the testis is Testosterone.
The function of Oestrogen :
Helps to develop the female body and the normal functioning of female secondary sex organs such as the uterus, vagina etc,
Testosterone
This male hormone is secret from Testis. During adolescence testosterone is more active, the appearance of a moustache and beard, change of voice, development of muscles, and strengthening of bones all are due to the testosterone hormone. Testosterone stimulates the formation of sperm.
Oestrogen is also found in the male body as well as testosterone is also found in the female body but both are in lesser amounts. Progesterone stimulates and regulates various body functions in females such as ovulation (release of egg from an ovary) and plays a major role in maintaining pregnancy.
Adrenaline is a hormone secreted by the adrenal medulla during stress. This is called as an emergency hormone because it initiates a quick reaction which makes the individual to think and respond quickly to the stress. The hormone increases metabolic rate.
Observe your locality and note down the symptoms of the hormonal disorder and make a table
| Symptoms | Responsible hormone |
| 1. Very short height (dwarf) | |
| 2. Unusual growth of body and bones | |
| 3. Rounded moon-like face thickening of the skin | |
| 4. Weakness, excessive urination, healing power delayed | |
| 5. Swelling of glands around the neck. |
Adolescence
It is one of the most important phases in human life. Several changes occur during this phase. Adolescence is the period between childhood and adulthood. This phase is commonly known as ‘teenage’. According to the World Health Organization (WHO), adolescence is the phase between 10 to 19 years of age. Rapid changes occur in the body and mind during this phase.
You also may notice changes in your body. During this phase you may have seen changes of physical structure such as weight, height, and complexion, you may also seen mental and behavioural changes. Endocrine glands and hormone secretion from them play a vital role in bringing about these changes.
During this phase of development adolescents begin to transition from childhood to adulthood. Eating disorders, mood-changing disorders, aggressiveness etc are usually occurrences. It is characterized by rapid physiological changes and psychosocial maturation.
Adolescence is also the stage when young people extend their relationships beyond parents and family and are intensely influenced by their peers and the outside world in general. This is a period of active growth and development of physical, sexual, social and emotional.
During this phase problems in growth and hormonal balance may occur. Height may be short or tall, irregularities in the menstrual cycle, obesity and the appearance of acne are common among adolescent girls and boys. Besides physical changes, emotional changes also occur during this phase.
Overjoyed, enthusiasm, togetherness, some sort of aggressiveness, eagerness to make a relationship, feel attraction to the opposite sex and others. Hormones play an important role. Hormones are capable of making a person more emotional and sensitive than usual. Teenage body not capable to cope with sudden changes so teenagers show some.
very odd behaviour and reactions. For elderly persons of the family, teachers and parents should be soft and keep in touch wit t e teenage boys and girls and should explain why these are happening such as the appearance of a pimp, swings of moods, anger, and aggressiveness are common to all.
All of them have crossed these stag During this phase teenage boys and girls compare themselves and if not he or she thinks up the mark he or she feels depressed. But adolescent boys and girls should remember that all individuals are beautiful in his/h own way. All of them have something to its own and can impress others.
Pimples and some other physical problems would be solved if they maintain proper hugs and exercise.
Emotion management-
Teenagers are more emotional. They feel happy after listening to (hearing) good songs and seeing movies. They show their joyfulness when their favourite team win and are morose at their defeat, they get angry and depressed to hear their criticisms.
Tears come to my eyes very often to hear the misfortune of others. All these are normal behaviour. But an uncontrolled expression of happiness, anger or sorrow affects our physical and mental health. Some uncontrolled expressions such as continuous playing horns of car and explosion of crackers without interruption after winning a game or vote.
Ranshake of car, shops in aggression. We need to control our emotions. We need to understand our feelings before expressing ourselves. We must understand our uncontrolled emotions and feeling that can damage others’ happiness. Therefore, we need to understand these things.
Teenagers must try to control their emotions and feeling. But if we suppress all these emotions in their mind then it will affect their mind and health. So it is needed to sublimate of emotions through other things like play, cultural programmes, deleting programmes etc.
expression of some feelings are
If the boys and girls who are passing the adolescence stages remember that
I am a good child of my parents because I love them they love me they have faith on me and I will be able to do something good for them in a different way. I want to see them happy.
Life skill education is a special behaviour which helps us to face various needs and challenges and try to control our emotions. During teenage or adolescence rapid changes occur. To cope with these changes we need to acquire life skill education to face the pressure of uncertainty of the environment and the challenge.
According to WHO—
Life skill—The abilities for adaptive and positive behaviour that enable individuals to deal effectively with the demands and challenges of every day.
According to WHO recommendation life skill education are as follows-
1. Self-awareness-
We need to identify our own liking and disliking successes and failures and learn to control them according to the situation.
2. Critical thinking-
After facing various, problems, solving them after proper analysis and changing behaviour accordingly. We also have to learn this.
What is Life skills? As recommended by UNICEF
Life skills-based education is a behaviour change or behaviour development approach designed to address a balance of three areas— knowledge, attitude and skill.
3. Decision-making-
We need to take proper decisions by controlling different confusing thinking patterns.
4. Creative thinking-
Need to take part in different creative acts like dance, drama, painting, sports, song and other cultural activities that will help to control emotions.
5. Problem-solving-
Identify the root of the problem and search for a suitable way to overcome this.
Problems Solving Four basic steps in problem-solving
6. Interpersonal communication-
It is very important to develop the habit to be a patient listener. It is also important to learn what to speak and how to speak.
7. Interpersonal relationship-
It is important to build perfect bonds with family members, friends, neighbours and other people around you. Good relationship-making is an art and an important part of life skill education. Problem-solving is a systematic approach to defining the problem and creating a vast number of possible solutions without judging this solution.
8. Empathy –
Understand the problems and feelings of others and treat it and express them.
9. Stress management
Identify the cause of mental pressure and practice the measures to reduce them. Engage yourself in a different type of work.
10. Emotion management-
Need to be aware about one’s own feelings and express those feelings properly. Need to control your emotions before expressing it. Say’No’ if the situation demand. We often fear if we say ‘no’ it will harm our relationship but if saying ‘no’ is good to solve the problem then it is right.
Life skills:
Life skills include psycho-social competence and interpersonal skills that help people make informed decisions solve problems, think critically and creatively communicate effectively build healthy relationships empathize with others and cope with managing their lives in a healthy and productive manner.
Why Life Skills Education?
Life Skills Education Because Of
All of us take food. Not only that, food is required by every living organism for their survival growth and development. Early human beings to meet their food requirements started hunting animals and collecting fruits, roots, and other parts of forest plants.
Among all the living organisms only green plants are autotrophs as they make their own food. On the other hand animals, as well as human beings are heterotrophs because they depend on plants and other animals for food.
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Food:
Since primitive times after settling human beings have been doing farming and rearing animals to meet their food requirements. Man discovered the methods of growing food. This was the beginning of Agriculture.
Agriculture is connected with discovering new and improved varieties of crops i.e. rice, wheat pulses, and rearing of different animals such as fowl, sheep, goats, cows, buffalo, etc. to get more eggs, meat, and milk.
Agriculture :
Crops:
Crops are the same type of plants grown in communities in a larger area. For example Paddy (rice), wheat, pulses, etc.
Crops are of various types :
| Types of Crops | Example |
| 1. Cereal | Paddy, Wheat, etc. |
| 2. Roots and tubers | Potato, Ginger, etc. |
| 3. Pulses | Musur, Gram, Pea, etc. |
| 4. Edible oil | Mustard, Sunflower, etc. |
| 5. Vegetables | Tomato, Cabbage, etc. |
| 6. Fruits | Bananas, Grapes, Cucumber, etc. |
| 7. Spice | Clove, Coriander, black paper, etc. |
| 8. Medicinal | Aloe vera, Serpentine, Cincona |
| 9. Flowers | Rose, Jasmine, Marigold (Gandha) |
| 10. Fibrous | Jute, Cotton |
| 11. Ornamental Plants | Cactus, Bougainvillaea etc. |
| 12. Drink Producing Plants | Tea, Coffee |
| 13. Sugar crop | Sugarcane |
One of the important sister branches of Agriculture Is Horticulture* Horticulture Is the science of growing vegetables, fruits, ornamental plants, etc.
In normal conditions, you will not see to grow watermelons in winter, oranges, and apples in summer. Growing of crops depends on several factors such as temperature, humidity, rainfall or water supply, quality of soil, etc. Some grow better In moderate temperatures, some are In low temperatures.
Crops are divided In two types on the basis of ‘ seasons—
1. Kharif Crops :
Kharif crops usually grow during June— July to September—October. High to moderate rainfall and temperature are needed for the production of Kharif crops, the production of these crops depends on the southwest monsoon. Growing and harvesting time respectively June-July and September-October. Examples of some kharif crops are paddy, maize, cotton, Jute, etc.
| Starting time | Time of harvesting | Weather condition | Example of crops |
| June-July | September- October | moderate to high temperature and rainfall | Paddy, (Rice), Maize (Jowar) Cotton, Jute, etc. |
2. Rabi Crops :
Rabi crops usually grow between October-November to March-April. Low to moderate temperature and comparatively less rainfall is suitable for the production of this type of crop. The beginning time is October – November and the harvesting time March-April. Rabi crop cultivation are not dependent on monsoon.
Examples of Rabi crops are wheat, barley, gram, pea, mustard, etc. Besides these two types of main crops, some crops are cultivated in between Rabi and Kharif during summer these are known as summer crops (During March to June), some pulses and rice, Maize are also grown during this season if the areas are well irrigated.
Rabi Crops :
| Starting time | Time of harvesting | Weather Condition | Example of crop |
| October -November | March-April | low to moderate temperature and less rainfall | wheat, barley grams, pea, potato, mustard, etc. |
Farmers have to take on different activities for a certain period of time to produce crops. The steps of activities or agricultural practices are as follows :
1. Preparation Of Soil Of Cultivable Land:
Plants grow in soil. So before plantation or sowing seeds soil have to be prepared properly. Soil is one of the most important natural resources which support the growth of plants. Soil is a complex mixture of several components both of inorganic and organic.
The composition of soil differs from place to place. You have noticed that the soil of near the seashore and Sundarban area are different that of the hilly region of Bankura and Birbhum.
Before showing seeds or plantation loosening of the soil is very much needed. Turning of the usually made by the help of hoe or plow or by a tractor. It makes the soil airier and water enters inside easily.
Earthworms, insects, lice, ants, termites, etc also make hole which tern the soil airier and nutrient-rich. Earthworm is known as the friend of the farmer, because they make hole in the soil to allow more air, losing the soil and enriching the soil dropping with nutrient mix excreta.
Beneficial microbes also add nutrients to the soil by decomposing organic substances present in the soil. Topsoil, the upper few centimeters of soil is nutrient rich. Turning of soil helps to get the plant its nutrient from the soil easily.
Turning of soil is the first stage of the cultivation process, we already understood the importance of turning of the soil. The process of turning the soil is known as ploughing.
Tools:
After ploughing a wooden or iron (Harrow or Leveller) is used to level the uneven agricultural land. It minimizes the soil erosion due to the action of water and air. Sometimes different organic fertilizers are mixed with the soil during the phase.
2. Sowing of seeds :
After the preparation of the field (soil) next step is showing of seeds. It is also a very important phase. Before showing the seeds it is important to verify whether the seeds are good quality or not-such as whether the see are healthy, drought or excess rain resistant and are free from any infection (fungus, bacteria, etc.) or suitable for the soil where it will be placed (sowing).
Nowadays with the advancement of science Agricultural Department recommend seeds suitable for the soil and its productivity.
Simple experiment
Seed Drill :
Nowadays improved sowing tools are used such as seed drill to sow the seeds. Through this tool seeds can be sowed at the right distance and requisite depth. The advantage of this tool is that it covered the seed by soil as a result birds cannot get access of the seeds.
The use of this tool also save time and labor. Why the farmers sowing seeds at dusk? To keep the moisture of soil around the seed and to protect the seeds from birds. Recently some cases farmers use some chemical substances with the seed in the pit to reduce the chance of infection of seeds.
In case some crop and vegetable (paddy, chili, tomato, etc.) seeds are sowed in seedbed randomly. After the seedlings come out and grow up to a certain limit, suitable seedlings are taken from the seed bed and replanted these in the previously prepared field. Transplanted seedlings after settling in new place grow there and produce crops. In such cases production increases.
3. Adding manure and fertilizer:
Plants require some minerals for proper growth. The different minerals (elements) found in the soil are called nutrients. Some of these nutrients are needed in large amounts and some are needed in very small amounts. The nutrients are needed in large amounts and are essential for plant growth are called macronutrients or macroelements.
Macroelements or macronutrients are
The minerals or elements required by plants in a very small amounts (traces) are called micronutrients or microelements or trace elements.
Micronutrients or trace elements
The deficiency of any of the macro and micronutrients in the soil reduces crop yield. Plants get most of the nutrients from soil. Although these nutrients are identified as elements but actually taken by plants as compounds.
Repeated use of the same piece of land for crop production creates a deficiency of soil nutrients. The crop yield becomes low. The deficiency of plant nutrients and organic matter in the soil is made up by adding manures and fertilizers to the soil of crop fields.
Manure
Farmers have been using cow dung as manure to improve the fertility of the soil for a long time. Manure contains a mixture of various organic nutrients suitable for plant growth.
Manure are of organic substances obtained from the decomposition of animal wastes, dead plants, and animals by the action of microbes. Manures are natural fertilizers. Manure is not very rich in nutrients (such as N, P, K, etc.) but it is rich in organic matter.
Soil nutrients are of two types—
1. Organic manure—
Organic manure is produced by the decomposition of animal wastes, dead plants, and animals. Farmers dump these types of waste products in a pit for a few days to a few months. By the action of microbes, these organic products turn into organic manure.
The problem with manure is that it acts slowly and occupies a lot of storage space and also take a long time to form Moreover, manure is not nutrient-specific. In the requirement of a particular nutrient, it is not effective. For this reason, chemical fertilizers which provide specific nutrients are also used in soil.
Compost Manure
It is prepared from straw, sewage waste, vegetable, and animal refuse weeds, fecal matter of animals, cow dung, etc. It is a biological process in which anaerobic and aerobic micro-organisms decompose organic matter.
Green manuring :
It is the practice of ploughing nodules bearing green leguminous plants into the soil for improving fertility. Mainly to increase soil nitrogen (N).
Fertilizer:
Fertilizers are inorganic chemicals synthesized in industries. They contain essential plant nutrients like nitrogen (N), phosphorous (P) or potassium (K). (= NPK)
These three important components are mixed in different proportions to produce NPK fertilizer. Fertilizers are available in the form of granules, water-soluble powders or solutions. Different kinds of fertilizers are available in the market.
| Fertilizer | Example |
| (1) Nitrogenous | Urea (an organic fertilizer), ammonium sulfate, ammonium nitrate, etc. |
| (2) Phosphatic | Superphosphate (Calcium hydrogen phosphate), Ammophos. |
| (3) Potassium | Potassium nitrate, potassium chloride, etc. |
| (4) NPK | Combine fertilizer of N, P, and K. |
Experiment: Take three beakers filled up with the same type of soil.
Beaker No – 1-Soil + Add urea
Beaker No – 2-Soil + Organic manure cow-dung.
Beaker No – 3-Soil + without any manure or fertilizer.
Add an equal amount of water in these beakers and placed the same type of.3 seedlings in three beakers. Observe it for a few days (10 -12 days).
Note your observations – the growth of seedlings in three beakers.
| Beaker No | Observation (Plant growth) | Remarks |
| 1 | ||
| 2 | ||
| 3 |
Calculate the growth rate and draw a conclusion- showing the effect of manure, and fertilizer.
Farmers often use chemical fertilizers to yield more production (crop). The excessive and unwise use of chemical fertilizers change the nature of soil- making it either too acidic or too alkaline and use of this type of fertilizer also kill the beneficial microorganism of the soil. Ultimately the fertility of soil decreases.
Inorganic fertilizer when used unwisely or not applied without testing the nature of the soil it does more harm than good.
For example-
When inorganic fertilizer like sodium nitrate (NaN03) is used in the field nitrate part is used by the plant and the sodium part remains in the soil. Repeated use of this type of fertilizer increases the amount of sodium of the soil which after mixing with water makes the soil alkaline (for NaOH).
On the other hand, the ammonium part of fertilizer- Ammonium sulfate [(NH4)2S04] is used by plants, accumulated sulfate part in soil then combines with soil water-form (H2S04). sulphuric acid which turns the soil acidic.
Moreover, excessive use of chemical fertilizers creates environmental hazards. These fertilizers finally reach the aquatic system (ponds, lakes, rivers, etc.) by rainfall, and irrigation making the water unfit for human consumption as well as destroying many aquatic life (fish and other aquatic animals and plants).
So presently effort has been taken to reduce the use of inorganic fertilizers and increase the use of organic manures. Now the question-Why the use of organic manure is better than inorganic fertilizers?
Fertilizers should be used only when they are required.
Several studies are been done how to retain and improve the natural condition of soil.
Use of biofertilzers –
Organisms which enrich the soil with nutrients are called biofertilizers. Biofertilizers are renewable and non-pollutant sources of plant nutrients such as nitrogen. Biofertilizers are used for specific crop plants such as pulses, legumes oil seeds, rice, etc. Biofertilizers make the soil porous and increase the air content of the soil.
Crop rotation-
Different plants use different types of nutrients. Particular soil loses essential plant nutrients when the same plants are cultivated repetitively in the same soil. Rotation of plants (crop) help to maintain the soil nutrients and able to restore the loss of nutrient because different type of plants use different, type of nutrients.
Crop rotation :
It is the practice of growing different crops in succession in the same field or soil.
Usually, leguminous plants (pulse-crop) are grown between two cereal crops (paddy, wheat, – maize, etc.). Cereal crops take away nitrogenous compounds from soil. The nitrogenous fixing bacteria. Rhizobium present in the nodules of leguminous plant (pulse crops) roots restores these compounds in the soil.
Rhizobium is a symbiotic bacteria (Rhizobium). These bacteria take nitrogen from the atmosphere and transfer it into nitrogenous compounds that plants can use. Some this use by the plant and remain mixed in the soil.
The benefit of crop rotation
Crop rotation helps to maintain soil fertility, and moisture and control pests and diseases.
4. Irrigation :
Water is the most important natural resource. No organism can live without water.
Water is needed for the
Water Sources
Generally, water sources are rivers, canals, reservoirs, lakes, ponds, tanks, wells, and underground water extracted through pumps and tube wells. The main thing of irrigation is to supply water from the water sources to the crop fields through canals, pipes, etc.
Electricity or Diesel pumps usually use to lift groundwater and water from ponds tanks and water sources and supply the water to fields by pipes or canals. Sometimes solar energy or biogas is used instead of electricity or diesel.
During earlier days and in some remote places traditional methods are used. The traditional methods are cheaper but are less effective. In this process misuse of water happens.. Plant bodies contain nearly 90% water.
To control the misuse of water during irrigation water is sprinkled on the crop plants in the agricultural field like a fountain. This method is known as the Sprinkler system. Water is supplied near the roots of the crop plant in drop by drop with the help of a pipe. This method is known as the Drip system.
5. Crop protection :
During cultivation, crop plants face different types of hazards which hamper crop production. Production-hampering agents may be weeds, pests or disease-causing micro-organisms. These agents need to be controlled. Protection from weeds – Many unwanting plants grow along with cultivated crops. These unwanted plants are called weeds.
Weeds compete with crop plants for water, minerals, light, and space. Thus their growth in crop fields is very harmful for cultivated plants. They hamper production as well as the. quality of the crop. Weeds also harbour pests and spread crop pests and crop diseases.
Weeds also create problems in harvesting the crop. It is, therefore, essential to remove these weeds from time to time. The farmers use different methods to remove it.
1. Mechanical method :
The farmers remove the weeds by hand (uprooted). Sometimes they cut the weeds very near to the crop fields and in between the rows by Khurpi or harrow [a comb-like tool (instrument)] hand hoeing.
2. Chemical Methods :
Sometimes some chemicals are sprayed on weeds to destroy (kill) them. These are called weedicides or herbicides. (2, 4-D, Dalapon, Picloram)
3. Biological control of weeds :
Involves the deliberate use of insects or some other organisms which consume and specifically destroy the weed plants but not damage the crop. Some common weeds are Parthenium, Chenopodium, Amaranthus, grass, Convolvulus, and wild oat.
6. Protection from pests (Pest control)
Many insects (locusts, aphids, termites, mites bugs, weevils, beetles, etc.) rodents (rats), and birds feed on crops or damage crops. These are known as pests.
Pest:
The insect pests like locusts fly in hordes and cause severe damage to the crop field. They eat the leaves of the plants. Some stem borer (insects) grow (Majra poka—Tryporyzo) inside the stem, and termites feed on the roots and stem. Pests also spread many diseases of plants.
Many microbes such as bacteria, fungi, and viruses also spread many diseases and reduce crop production. Fungi (Phytophthora) cause late-blight disease of potato and rust diseases (by— Puccinia) in wheat. Bacteria cause wilt disease. Common Paddy Pest is yellow stem borer Majra.
Poka—Scirphaga is incredulous it is previously known as Tryporyza inertias. Green leaf hoppers is also a common pest that transmits viral disease.
Pest control
Chemical and biological methods are employed to control pests.
In the chemical method of controlling pests some pesticides (chemical mix with water or oil) are sprayed in the field by hand-operating machines or by power sprayers. Some commonly used pesticides are DDT (Dichloro diphenyl trichloroethene)
BHC (Benzene hexachloride or Gammexane) Malathion, zinc sulfide/zinc phosphide (use to control rats and other rodents, etc.
Different Types of Pesticides and Their Applications
Though use of chemical pesticides yield good and quick result initially but these have some nfler effects. Chemical pesticides are not environmentally friendly.
To avoid the hazards of chemical pesticides biological control methods have been taken to control pests.
Biological Control method
In this method, one organism is used to control another one. Such as some birds, insects or other organisms are deliberately put into the field to kill the pests selectively. Ladybird beetles and some ant-like insects (Hymenopteran-Parasitoids insects) are used to kill the VVphids’one of the harmful pests of crops.
Some fungi, Protozoa, bacteria, and viruses are also used to control pests. Biological control is a slow method but it is highly specific and nonpolluting.
7. Harvesting :
After the maturation of food grains or crops Harvesting is done. Some crops are harvested by hand (usually vegetables). Sometimes some tools are used such as sickle to cut the crop plant very near to the ground level (crops like paddy, wheat, Bazar, mustard, etc.)
Threshing –
Threshing is a process where the edible part of the grain crops (such as paddy, wheat, mustard, etc.) are separated from the crop plants. Sometimes it is done by beating the harvested plant part against the ground or any hard substances sometimes cows are used to separate of grains from crop plants. Harvesting and threshing both can be done with the help of a machine known as a combine.
Winnowing :
Small farmers who have small cultivated land usually use this process. Usually, they take grains already been separated by threshing and drop it into the ground from a certain height in a wind-blowing area.
The chaffs fly away as they are light and grains fall below in the ground. Just below. Combine machines can serve all these three purposes harvesting, threshing, and winnowing.
8. Storage :
Most crops are harvested only once a year some time twice. Thus they are available in plenty during a selective time, (such as paddy during Nov – Dec). For getting seasonal foods regularly throughout the year food grains are stored in safe storage. Storage of food is a hard task. It involves a great range of activities and precautions.
The primary condition of storage of food grains it should be reasonably safe and prevent damage. For a long time storage measures should be taken to protect the food grains from insects, rats, and microbes (viruses, fungi, bacteria).
The fresh crop has more moisture before storage grains are dried under the sun before storage. Infestation of microbes (such as viruses, bacteria fungi) and insects can be resisted if the food products have less humidity.
Food materials can be stored usually in two ways depending upon whether they are dry (nonperishable) or spoil at room temperature (perishable). Dry or nonperishable food products such as cereals, pulses, flour, sugar, spices, nuts, etc. are stored in room temperature in suitable containers or bags. This mode of storage is called ‘ ‘dry storage’.
On the other hand, the food products such as fruits, vegetables, fish, meat, eggs, milk, etc. (perishable food material) are stored at a low temperature. This method of storage is called Cold storage. The farmers store grains in Jute bags (Basta) or metal containers.
For large-scale storage of grains (Dry storage), granaries or air-tight rooms or Silo are used. Grain Silos are steel-bodied cylindrical structures. They are constructed in such a way that provides for aeration, and temperature control protection from insects worms, rodents, birds, and other animals.
They have the facilities to spray pesticides, and fumigants,s and for inspection. Nowadays Nitrogen gas is continuously circulated through the granaries to prevent pests. Nowadays” liquid nitrogen is also used to preserve seeds (cryopreservation)
Paddy :
One of the most important principal food in the world is rice. Bice is the product of paddy. Paddy is one of the major crops of India as well as West Bengal. You can gather much information if you ask the people associated with cultivation-How many types of paddy are cultivated in India? What are their sowing and harvesting times in major paddy-producing states, different control methods of paddy pests, etc?
Major paddy-cultivating states of India
Paddy is cultivated in almost all the states of India. The major paddy-producing states are West Bengal, Uttar Pradesh, Andhra Pradesh, Odisha, Tamilnadu, and Punjab. Before going to different types of paddy, let’s see the nutritive value of rice –
Rice contains 79.1 % carbohydrates, 6% Protein, fat 1 – 2% of and another element of 04% including vitamins, minerals, etc. Rice also contains vitamin B complex. Oil is also produced from rice bran.
On the basis of season and method of cultivation, paddy are of three major types-
work for students:
| Months of year | Name of the paddy | Now what type of paddy cultivation going on | Season of paddy |
On the basis of productivity, paddy are of two types –
Aush
Aush is generally sowed in the field after the Rabi crops and usually sowed directly in the Agricultural field. Aush paddy can grow more or less in all types of soil such as alluvial, loamy, and clayey. In some areas, Aush seeds are sowed in a prepared seed bed instead of direct showing in the field.
Aman
It is a monsoon crop. Cultivated during monsoon season such as during the rainy season. Aman paddy produces better result in clay soil, though this paddy is also cultivated in any other type of soil. The main paddy cultivation in our state (West Bengal) is Aman.
Our country have many varieties of Aman paddy. Different indigenous varieties are known by different names in different regions.
Good varieties of Aman paddy are –
Aman paddy is cultivated in two phases – seedlings are prepared in seedbeds and these seedlings are then planted in the well-prepared agricultural field. Usually, seeds are to be treated properly before sowing them in the field.
Boro is a summer paddy after cutting the Aman paddy seed bed for Boro is prepared. Seedlings are transplanted later to the main cultivating land. Boro paddy is harvested in March – April. Boro paddy is mainly cultivated in the field where irrigation facilities are present. Some paddy grows faster, some medium, and some are slow growers.
On the basis of time duration or time is taken for maturity paddy are of three types-
A comparative study of three types of major paddy – cultivating time, seedbed preparation, transplantation of seedlings, showing seeds, and harvesting time.
Most of you have seen mango. It is known as the king of fruits. It is a juicy fleshy fruit with a special odour of some varieties. Especially during summer if you go to a fruit market you will find different varieties of mango.
Try to make a list. (One example given).
| Mango type | Growing time / Season | Photograph/characteristics |
| 1. Himsagar | April-June | medium size, sweet juice. |
| 2. | ||
| 3. | ||
| 4. |
Distribution :
The original home of mango is India (indigenous to India). Later it spread to other countries like Srilanka, Myanmar, Malaysia, Indonesia, East Indian islands, etc. The scientific name of the Mango plant is Nanjifera Indica. Mango is found more or, less all over India. In West Bengal, the major mango-producing districts are Malda, Murshidabad arid Nadia.
Food value or Nutritional value of mango :
Mango contains carbohydrates, protein, fat, and minerals (Ca, P, Fe, etc.). It also contains vitamins A, B-complex, and C in good quantities. Mango is a yellow fruit, it contains Beta carotene, water, and also some fiber. Beta carotene helps to better eyesight.
Weather:
Though mango can grow up to a height of 1500 meters or more above sea level. But for its proper growth clear sky and an absence of snowfall and mists is needed. So their growth is high in plain land. Rainfall and mist damage mango buds.
A mango tree can grow in different soil. But the most suitable type of soil for mango plant growth is the alluvial soil of the river basin and fertile loamy soil. Sandy and clay soil are not suitable for mango cultivation.
Some varieties of mango usually grow in India are— Alfonso, Amrapali, Bombai, Dasheri, Dudhiya, Phazli, Himsagar, Langra, Mallika, Mulgoba, Neelam, Totapuri, Begumfuli, Chausa, Bearti, Golapkhash, Peyaraphuli, Jhumka-phase, etc.
Some mango have specific test and flavours. Some mango grows in large quantities. Although their products are varies in different parts and at different times.
Propagation-
Propagation of mango from seed is common practice. But seed c(pes not have all the original characteristics of the mango tree. Therefore, nowadays seedlings produced by grafting have been practiced. Seedling produced by this grafting process has all the original good qualities.
Grafting-
Grafting is a horticultural technique where tissues of plants are joined so as to continue their growth together. In grafting the upper part (known as ‘scion’) of one plant grows on the root system (known as ‘stock’) of another plant.’Scion and Stock’ The upper high-quality plant part (scion) attach with stock the lower part (stock) during grafting.
This grafting process of the mango plant is usually done in July – August. There are many types of grafting processes are used, such as veneer grafting, chip budding, stone grafting, etc.
Process:
Tea:
The World’s largest number of people have an experience of Tea. The term ‘Tea’ most probably comes from the Chinese word ‘Tey’. Tea is the dried leaf of a bush (Tea plant) plant. It contains theine and caffeine (a type of alkaloid) and when it is added to boiling water, with or without sugar or milk it gives a very cheap stimulating drink.
Thus it is the most important beverage crop of India. Tea-producing countries—World’s largest tea-producing countries are China, India, Srilanka, Kenya, and Indonesia. The tea plant (Camellia sinensis) is native to East Asia, the Indian subcontinent, and South East Asia.
But pow it is cultivated across the world in tropical and subtropical countries. In India Assam, West Bengal, Tamilnadu, Karnataka, and Kerala are the main tea-producing states. In West Bengal entire Tea is produced in three northern districts Darjeeling, Jalpaiguri, and Coochbehar (nearly 25%).
Most of the Tea plantations in India are found at elevations varying from 600 to 1800 meters above sea level, where rainfall is heavy but no water logging.
Soil type for tea—
Tea is cultivated in acidic humus-reached soil mainly in the slopes of the hills where rainfall is good but no water logging. Virgin forest soils rich in humus and iron content are good for Tea plantations. Different types of Tea are grown in India among them. Darjeeling Tea, Assam Tea, and Nilgiri Tea are famous.
Three types of Tea are commercially found in the market,
Black Tea accounts for nearly 75% of world production. Tea bush is a tropical and sub-tropical plant and thrives well in hot and humid climates. The ideal temperature for its growth is 20° -30°C and temperatures below 10°C and above 35°C are not suitable for the plant.
Tea is an aromatic beverage. It is the most consumed beverage in the world. Tea has a variety of positive health benefits.
Humus and iron-containing forest soil is good for Tea plantations. A relatively large proportion of phosphorus and potassium in the soil gives special flavor to Tea as is the case in Darjeeling. Darjeeling Tea is famous in the world for its flavor.
Three major types of Tea plants are cultivated. These three under the genus Camellia are
Germination of seeds is done on the sand bed. Seeds can be germinated faster by placing them in a plastic bag and covered with sphagnum mass for moisture maintenance. Seeds germinate within a month or so. Germinated seeds are transferred to the nursery beds in polythene packets.
Nursery beds should have a water draining system and germinated seeds should also be kept in moist condition pots are to be kept in a warm location with bright indirect light. Seedlings become ready in 15 – 18 months for transplantation.
Vegetative Propagation
An alternative process to grow Tea plants is cutting or layering. For cutting an angle cut on the stem or branches (with node area) of the plant and dip it into the rooting hormone. Thus the branch are bended and placed in the soil. After the appearance of the root then cut it from the mother plant and plant it to another place.
In grafting 3-4 centimeters (cm) long branches are cut with leaf and a swollen dormant axillary bud and fixed with stock portion of other plant and are kept as in the previous process.
| Steps of Cultivation | Works done |
| 1. Preparation of Jand | For the preparation field, old plants are first removed then fields are ploughed. The same grass or other plants are cultivated in the field for the source of different minerals. Organic manures and NPK type of inorganic fertilizers are also applied according to need. Humus content of the soil to be increased. |
| 2. Transplantation of seedlings | Deep holes are made in the field one week of the plantation. These holes are filled with topsoils containing humus. Then 12 -18 months seedlings are transplanted. Wet leaves, straws, etc. are kept at the base of the transferred seedlings. |
| 3. Additional arrangement | Tea plants are grown under shade in tropical and subtropical regions. Trees are provided shade and shade reduces the surrounding temperature by absorbing some part of solar radiation. Fallen leaves of shaded trees enrich the amount of humus in the soil. |
| 4. Weed control | Weedicides are sprayed to control the mono and dicotyledonous weeds. |
| 5. Application of fertilizers | Urea, ammonium-sulfate, ammonium nitrate, calcium, and phosphate-containing fertilizers are used to maintain the minerals balance mainly for nitrogen. |
| 6. Irrigation | During less rainfall or dry season (October – February) generally, the sprinkler method of irrigation is practiced. |
| 7. Harvesting | The tender part of plant branches like 2 – 3 leaves and one bud are plucked. Quality of production very much depends on the plucking of Tea leaves. 35 – 40 rounds of plucking in a year is general practice in commercial Tea plants. |
| 8. Tea Manufacturing | Plucked parts after drying pass through many steps to become consumable parts. Different machinery are used in this process. |
| 9. Tea tasting | Experience Tea-Taster are used for their process. They test the color, and flavor before marketing. |
Different Types Of Animal Based Food Production
We have learned that plants are the major source of our food. From animal sources, we also get food items. We get eggs, honey, milk, meat, fish, etc. from animals. These items give us mainly proteins, fat (lipid), vitamins, and minerals. We have to take care to improve animal food productivity.
Animal Husbandry is a branch of agriculture that deals with the breeding, feeding, and care of domestic animals which is the main source of food products.
Animal Husbandry:
The branch of agriculture deals with the breeding, feeding, and carrying of domestic animals.
Honey Bee
Most probably all of us have get the test of honey. Many of you have seen honeybee. Some of you may have experience of honey string. Honey-bee forms their nest known as beehives in the branches of trees, corners of houses, bushes or in other places.
We get honey and wax from honey-bee. These two are extracted from beehives. Besides the beehives in the branches of trees, corners of houses etc. artificial beekeeping and beehive are also made. The scientific method of beekeeping is known as Apiculture.
Types of Honey-bees – Honey-bees are of four types—
Honeybee is a social animal (Insect). They have a well-organized society with a division of labor (specific job).
Construction of beehive and Production of honey
Worker honey-bees construct the bee hive with the wax present in the wax gland in their abdomen. Numerous hexagonal chambers known as cells are present in a beehive. The cells of the comb are of various types ‘storage cells/ brood cells’,’ queen chamber’ etc.
Formation of a honeycomb or hive, worker bees collect nectar and pollen from flowers. They store the nectar and pollen in their honey sac of their own body. In a honey sac nectar mixes with saliva, to form honey. Worker bee vomits this mixture in the honey chamber and fan it with their wings. As a result, water is vaporized and produces honey.
The life cycle of honey bee
It is necessary to know the habit and life history of honeybees. Artificial bee culture needs all these. In the life cycle of a honeybee has 4 stages.
Egg→ Larva→ Pupa→ Adult
During the first 2-3 days all larvae are fed on a special food “Royal Jelly” secreted by the pharyngeal glands of the young workers. After this important food “Bee bread” (mixture of honey and pollen .grain) is given to the larva. Queen-forming larvae are fed on royal jelly for full larval life.
Honey :
Honey is a sweet, viscous fluid obtained from a honeycomb prepared by a honeybee. Honey is a mixture of nectar pollen and the saliva of a honey bee.
Honey is composed of water, sugar (levulose, sucrose, dextrin, dextrose) minerals (like calcium, iron, phosphates, and manganese) vitamins B-complex, A, and C.
Artificial beekeeping :
The amount of honey from beehives of wild honeybees are very little and are not regularly available. To overcome these difficulties artificial beekeeping has been introduced. The scientific method of beekeeping has been developed after extensive studies of bee behavior. A rearing place for honey-bees be it natural or artificial is termed as apiary.
1. Indigenous method –
Beehives in natural conditions such as in the branches of trees, on the wall or on cornices of roofs, are found out. Sometimes wooden boxes, pitchers, (earthen vessels) are. placed along the route of honey-bees movement. Honeybees may construct beehives there.
Later the honey-bees of this comb are driven put from the hives by using smoke, fire, water or fumes. Beehives are collected after honey-bee living the comb and honey is extracted from the hives.
2. Modern method –
In this method, the artificial beehive is constructed based on natural beehives. In this device chamber for rearing the young ones is placed at the bottom and the honey chamber is located at the top. One queen and some worker honeybees are collected and are placed in the artificial beehive.
It is seen that within few days some more honey-bee have come and joined with the team of honey-bee. Within a short time lots of honey bees are produced from the eggs laid by the queen. Worker honey bees collect nectar from nearby plants.
For this reason near the apiary, there should be some plants like mango, Jamun, lemon, guava and some different type of flowering plants. A special type of honey extractor are used for extracting pure honey from the artificial beehive.
Bee wax:
Beewax is secreted from wax gland of worker bee. They use it in the construction of hives. This is used by human being for several purpose like manufacturing of cosmetic goods, cold creams, shaving creams, candles, lipsticks, lubricants, etc.
Fish is a valuable and easily accessible source of food, rich in protein content. Fish provides us with nutritious food, oil, fertilizers, and many other useful products. The fishery is the scientific culture of fish and other edible aquatic animals such as prawns, crabs/snails, mussels, etc.
Pisciculture is the culture of fish:
Fishes are cultured in inland water reserves mainly in ponds, Canals, Paris, etc. Actually, fish are only captured from other inland sources like rivers, lakes, etc., and also from marine sources.
On the basis of the management of fish production fish can be of two types
In the water reserves of inland like ponds, bhari, canals, and shallow water mainly fresh water and brackish water fishes are reared.
Pisciculture in freshwater-
Three major crops like Catla, Rohu, and Mrigal are indigenous to our country and enjoy much popularity in our markets under proper cultural conditions they grow well.
Exotic carp (foreign carp which cope up with our environment and grow) like Grass carp, Silver carp, and Cyprinus carp (American Rohu) were introduced during the post-independence period in the country.
Carp
Carps are freshwater bony fishes covered by large scales, absence of scales on triangular head, accessary respiratory organ, and teeth in the jaw but have a swim bladder. example Catla, Rohu, Bata, etc.
Aquaculture: Using various types of water resources the production of useful aquatic plants and animals like prawns, fish, lobsters, crabs, mollusks, etc. are called aquaculture.
Pisciculture – The production and management offish is called pisciculture.
1. Collection of eggs and spawns :
During monsoon months (June to August) when the rivers are overflooded the fish migrate to adjoining shallow water lands. (This is also the breeding season of fish). These submerged shallow areas act as breeding grounds for the carp. The eggs are collected 12 -14 hours after fertilization.
Fertilization is a process of the unification of sperm and ovum (egg). Fertilization of fish is external and occurs outside the body. Instead of collecting eggs from the breeding ground egg are allowed to hatch in hatching pits. After hatching fries (spawns) may directly be collected from the breeding ground by specially made frets. Sometimes fertilized eggs are also collected and rear them in a hatching pit.
Artificial method of breeding or induced breeding :
Major carp do not breed in tanks, ponds or any other short confined water. To overcome this both male and female major carp are injected with pituitary extracts injection and are forced to release sperms and ovum (eggs) in the water where fertilization occurs. This process is called induced breeding.
Induced breeding –
Induced breeding (= hypohydration) helps to get sperm as required, minimize the carrying cost, and to get pure fertilized eggs of a particular type.
In Induced breeding of carp –
Pituitary glands of fishes are collected and after some processing pituitary injection is made. Two male and female mature fishes are selected for this purpose. Both of them are injected during this process. After some time both males and females release sperm and ovuk respectively.
Development of Adult fishes from spawns
Fertilized eggs collected by the fish farmers are reared in a small ponds to produce spawns. This pond is known as a hatchery. The spawns then are reared in different ponds or tanks one after one to produce adult carp.
For better results and full utilization of different food levels of ponds both indigenous (Rohu, Catla, and Mrigal) and exotic fishes (such as Grass carp, Silver carp, and Cyprinus carp) are cultured together in the same tank. This combined culture is known as Composite mixed fish culture or Polyculture.
The culture of major indigenous carp like Catla, Rohu, and Mrigal is known as Composite fish culture. Fish used in this system include Catla and Silver carp which are surface feeders Rohu and column grass carp are feeders and Mrigal and common carp which are bottom feeders.
Composite fish culture :
| Fish | a layer of food collection In water | |
| Indigenous | exotic | upper layer |
| 1. Catla | Silver carp | |
| 2. Rohu | Grass carp | middle layer |
| 3. Mrigal | Americal carp or common carp | lower layer |
Importance of composite fish culture :
Sewage-fed fish culture
Sewage water is generally black colour and mixed with waste products of houses, factories, and municipalities excreta and urine also remain mixed with this water. Various organic and inorganic substances are present as solids in sewage. An inorganic substance is present in the sewage water as fertilizer.
As a result phosphorus and nitrogen increase in water. These help the growth of phyto¬planktons. With the production of large quantities of lshinB phytoplankton, zoo-planktons, and other insects are also increased in number. Fishes use these phyto and zoo planktons and other insects as food.
So there is no need to supply supplementary food from outside. However, it should be kept in mind that using untreated sewage in culture tanks or ponds harms the fish. Prior treatment of sewage is needed before mixing with water in cultural ponds. Sewage is used in fish culture in East Kolkata Bharies.
Food value of fish :
Fishes are protein-rich food with essential amino acids, fatty acids, and various minerals, such as Ca, P, Na, K, Mg, S, etc., and some vitamins like vitamin A, D, C, and B- complex.
Poultry provides the best source of animal protein and fats. The practice of keeping and breeding of the birds like hens, ducks, turkeys, and geese is called poultry farming. In India chicken (domestic fowl) is the most favorite domestic poultry bird. We get major quantities of eggs from poultry birds.
Classification of Fowls (on the basis of usefulness)
The poultry industry has improved a lot in the last two decades. A huge increase in egg production in India is called the silver revolution.
Fowls are of two types on the basis of weight-
Fowls lay eggs but not all type of fowls incubate their eggs. These are of two types.
The practice of poultry farming needs good care for food, shelter, and disease control of fowls. Basically, two systems are commonly followed in our country, rearing fowls in battery cage / or cage systems and the Deep litter method.
Battery cages are the predominant form of housing for laying hens. In this method, the separate cage is allowed to each fowl. Fowl can easily sit or stand in the limited space of a cage. Many such cages are arranged side by side.
The floor of the cage is sloped as soon as fowl lays an egg, it is deposited in the groove protruding (outer projection.) from the cage. Food and water containers are attached outside the cage. The container for collecting the excretion are located below the cage.
Space is limited inside the cage the fowls get little opportunity to move their body. As a result, most of their energy came from food are used in bodybuilding and the production of eggs.
The deep litter method is one sustainable method of managing chicken litter in the chicken coop that many small poultry owner use. Deep litter system based on the repeated spreading of straw or sawdust or both and some other materials in indoor booths.
An initial layer of litter is spread for the animals to use for bedding material and to defecate in and as the litter is soiled new layers of litter are continuously added by the farmer.
In this process, a greater number of birds are reared per limited of area.
Litter is a bed made on a clean floor for the animal with small pieces of straw, sawdust, dry leaves, paddy, cotton seeds bran of barley, maize, mango peels, etc. Straw and other substances spread over sawdust and a thick bend of 10 -15 centimeters are made.
As the Fowls begin to inhabit the excreta of fowl mixes with the litter then new 5 cm litter layer form over the old one as a result 15 – 20 cm permanent litter is made. The litter bed containing room should be airy and be well lighted. The beneficial microbes and nematodes of litter make a healthy environment.
Food and water are placed outside the wall of the deep litter room in such a way that the fowl can easily get their food and drinks through the bars. A nest is placed in the wall of the room where the fowl go and lay eggs.
Through the deep litter method, farmers get the following benefits –
Eggs and meat contain high-quality protein and with all nine essential amino acids. Eggs are an excellent source of choline, calcium, and selenium and a good source of vitamin A, vitamin D, vitamin B12, Phosphorus, and riboflavin.
Both egg and meat contain a good quantity of minerals. An egg and meat contain nearly the same amount of iron (Fe), however, the iron in meat can be better absorbed by the body than the egg. This is because that the phosphate in the egg yolk will combine with the iron affecting the absorption of iron. Meat contains more potassium but less sodium than the egg.
Poultry disease :
Poultry birds suffer from various disease-causing agents such as—viruses (Fowl pox, Ranikhet), bacteria (Tuberculosis, Cholera, Diarrhoea), fungi (Aspergillosis), parasites (worms, mites, etc.) They also suffer from nutritional deficiency diseases.
Broiler — Broiler is a hybrid fowl. They are used for meat only. They are the product of the mating of male Cornish variety of fowl with female white Plymouth variety.
Male Cornish + Female Plymouth = Broiler
They grow very fast. They reach marketable size within 5-7 weeks whereas others take 12-16 weeks.
If you look around you will see a large variety of living organisms. It may be plants, animals, fungi, etc. But there are also several organisms that you cannot see with your naked eyes yet these organisms are around you.
Those organisms which are not visible with the naked eye and are viewed under a microscope only are called Microbes. If you increase the area of observation, the range and variety of organisms that you see would increase. This is the biodiversity of organisms.
Biodiversity :
(Bios = life, diversity = forms) Biodiversity in short is the number and types of organisms present on earth.
Microbes :
The word microbe (microorganism) is used to describe an organism that is small and normally it cannot be seen without the aid of a microscope example viruses, bacteria, fungi, Protista, etc.
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Activity :
Microbes or microorganisms are a number of large, extremely diverse groups of organisms. They cannot be seen without the use of a microscope.
Microbiology—Scientific study of microbes.
Microbes are the most primitive organisms existing from the beginning of life to earth till now. The first existence of microbes (cyanobacteria) have been recorded 3-5 billion (350 crores) years back. Microbes include—viruses, bacteria, fungi, archaea, and Protista.
Characteristics Of Microbes
Staining :
Microbes are. microscopic organisms. Before observing microbes under the microscope these organisms are colored by different substances, these coloring substances are known as stains and the process is known as staining.
Types Of Microbes :
Microbes are mainly belong to 4-major groups.
Viruses though acellular are also treated as microbes, Virus can be seen only by an electron microscope.
Bacteria
In many cases have a sac-like structure, (outgrowth from plasma membrane) mesosome, helps in respiration.
Protozoa :
Some protozoa have pigments that can produce food in their body such as Euglena.
Fungi
Algae :
Virus
The virus has not a typical cell. Viruses are called acellular because they have no protoplasm and they only behave like living organisms when they come in contact with a living organism.
Viruses can only be seen by electron microscope. Their possible existence was first noticed by Edward Jenner during his research with smallpox victims in Europe in 1796. But until the discovery of the Electron microscope, their detailed study could not be done. The term Virus’ means ‘poison’ (the Latin word)
Interrelationship With Living World—Symbiosis And Saprophytism
Some disease-causing microbes enter Into a particular part of the body or a particular type of cell (such as malarial parasite inter RBC, liver cells). Their growth and reproduction depend on the host cell.
They collect food and get shelter in particular cells or organs. These microbes later hamper the normal functioning of the host cell and system. The interrelationship between the host and parasite is called parasitism.
Microbes influence man in many ways. Microbes are known to cause various diseases in man and other organisms and for Deteriorating food, .clothing, furniture, etc. But some of their activities are useful for us. Such activities include medicine (antibiotic production. Production of dairy products and fermented beverages, sewage treatment, etc.
Harmful Effect Of Microbes
Many diseases of humans, plants, and other animals are caused by microbes. Microbes can enter inside the human body through air, water, food, blood, and also sometimes by a simple touch.
| Disease causing agents | Diseases |
| (1) Bacteria (Bacterial diseases) | (1) Tuberculosis, a certain type of Diarrhoea Cholera, Typhoid, Diptheria, Tetanus, whooping cough, Pneumonia, etc. |
| (2) Virus (viral diseases) | (2) Influenza, Pox, Polio, Measles, Hydrophobia Dengue, AIDS, etc. |
| (3) Fungi (Fungal diseases) | (3) Ringworm, Allergy diseases of the throat and lung, food poisoning sometime Diarrhoea, Aspergillosis |
| (4) Protozoa (Protozoal diseases) | (4) Amoebiasis, Giardiasis, Malaria, Kala-azar, Sleeping sickness, etc. |
Activity Work :
Make a list of ways of the entrance of microbes In the body and cause diseases.
Microbes help in human welfare :
Nitrogen is an essential element (Macro element) which is important for plant body formation. (Protein formation) and growth. Plants collect their nitrogen from the soil. Some Microbes (N2-fixing—bacteria) fix atmospheric nitrogen in the soil. Some free-living nitrogen-fixing bacteria present in soil are Azotobacter and Clostridium.
Few species of mushrooms are poisonous. Many of these deadly fungi bear an unfortunate resemblance to edible species, for example, Amanita (Deata cap, colorful)
Some nitrogen-fixing bacteria form a mutually beneficial association with the plant. This association is called symbiosis and these bacteria are called symbiotic bacteria: The most important of the symbiotic nitrogen-fixing bacteria is Rhizobium. They live in the nodules of leguminous plants root such as peas, grams, beans, etc.
Rhizobium produces Nitrogenous compounds for the plant and shares it to plant, on the other hand, plants give them shelter.E.coli and some other symbiotic bacteria present in the intestine of human beings (getting food and shelter they’re) help in the production of Vitamin B12 which helps in the production of hemoglobin of RBC.
Leguminous plants before the preparation of cultivating fields are mixed with soil to increase soil nitrogen. Sometimes more than one organisms live together and share its nutritional product.
For example Lichen – an association in between algae and fungi. The fungus partner supplies water and minerals to the algae partner and the algae prepares food for itself and share it with the partner. partner.
Many fungi and bacteria take part in the decaying process,, or decomposition. The process of collecting nutrients from dead decaying organic body and completing of the nutrition of their own is known as saprophytism.
Saprophytisms :
Many Microbes grow on dead animals and plants and help in the decay of organic matter. They break down complex organic matter into simple forms by the secreting enzymes. They also consume some nutrients after breaking down the complex organic forms Role of microbes in Environment.
Agriculture :
Free-living nitrogen-fixing bacteria (microbes) fix nitrogen in the soil such as Azotobacter, Clostridium, and Plants collect it from the soil. Symbiotic nitrogen-fixing bacteria Rhizobium forming nodules in the root of leguminous plants. (Pea, Gram, Pulse).
Plants take Nitrogen (N2 ) from the atmosphere and form nodules after the decomposition of the nodules nitrogen content of soil increases. During the preparation of green manure many leguminous and nonleguminous crops are grown in the field and plowed back into the soil when they are still young and green.
This practice helps to enrich soil nitrogen, phosphorus, calcium, sulfur, and other minerals. Nitrogen-fixing Cyanobacteria (blue-green algae)symbiotic association with several plants, for example, Azolla (fern). Most of plants, use soil, Nitrogen when it is in the form of Nitrate (N03 ) or NH4+.
Anabaena is Of great importance to agriculture. Anabaena (Azolla) resides in the leaf cavities of the fern Azolla and it fixes nitrogen. The decaying fern plants used in the field, before cultivation, as green manure. They decompose and, enrich the field for the next crop.
Some microbes present in soil also break the organic nitrogenous compounds and release NH3 (ammonia) the process is called ammonification and again ammonia converted into nitrite and then nitrite (N03) by some nitrifying bacteria.
This process of (Nitrate) N03– formation from Ammonia (NH3) is called nitrification. There are some other microbes (bacteria) that break nitrogen compounds and free nitrogen from compounds; this process is known as denitrification.
You may have noticed that after cutting Jute stem have been submerged in water for few days.
Production of medicine
Many life-saving drugs, Antibiotic medicine are produced from microbes mainly fungi and bacteria. Some organic compounds produced by these microbes can arrest the growth of other bacteria, for example, Streptomycin, Ampicillin, Chloromycetin, etc. Antibiotics are chemical substances the secreted by some microorganisms which inhibit the growth and development of other microbes (pathogens).
Alexander Flemming the father of antibiotics, first discover penicillin from the fungus Penicillium notatum. This was the first antibiotic which inhibit the growth of bacteria. This saves the life of millions and millions of people all over the world.
Vaccine
After the entry of some microbes like viruses, bacteria, protozoa, and fungi, they produce some toxic substances inside the body. These harmful agents (proteins) which enter into the body is called an antigen.
To prevent this antigen body produces some proteinous substance that prevents the entry and harmful activity of antigen called Antibody. Antibody attack and destroy the antigens. The natural system of body protection is called immunity.
To prevent some diseases some dead or weak microbes (viruses, bacteria) have been introduced in the body, which tiger body produces antibodies to fight against these antigens. The natural system of body protection is called immunity.
To Prevent some diseases some dead or Weak microbes (viruses, bacteria) have been introduced in the body. which tiger body produces antibodies to fight against these antigens. This process is called vaccination.
By this process, body is able to protect these diseases such as, polio, typhoid, cholera, diphtheria, etc. The process of improvement of body immunity is called immunization.
Vaccine and Vaccination :
A vaccine is a biological preparation that provides immunity (active acquired immunity) to a particular disease and the process by which immunity can grow by using a vaccine is called vaccination.
Immunization :
Immunization is the process by which a person or animal becomes protected from disease.
Treatment Of ‘Waste Product’
If human feces, urine, food residue, and decaying substance are not treated properly some infections may happen. These are risks for human health. Some microbes (bacteria) live in less oxygenated conditions can break these compounds. into utilizable and harm less products.
Plant Kingdom:
All of we know is that plants have a great role in our life. We collect different ingredients from plants for our food, clothes, medicines, and household materials. Plants parts are used in industries as raw materials (like Tea, timber, etc.). Animals inhaled oxygen which comes from plants during the process of photosynthesis.
Besides some plants reduce the extent of environmental pollution by absorbing pollutants. Plants prevent soil erosion, organic manures are also made from plant parts. Plants have a great role in controlling the temperature of surroundings rainfall wind velocity. ‘
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Bamboo
Bamboo is a common plant have no or fewer branches. Bamboos are evergreen perennial flowering plants. Bamboos like other grass (bamboo is a type of grass of the family Poaceae) have long stems whose nodes are solid and whose inter-nodes are long and hollow.
Bamboo are one the fasted growing plants in the world. Certain species of bamboo can grow 91 to 100 cm (3ft) within a 24-hour period at a rate of almost 4 cm (.1-5 inch) per hour. Giant bamboos are the largest members of the grass family.
Bamboos are of notable economic and cultural significance in South Asia, South-East Asia, and East Asia, being used for building materials as a food source,s and versatile raw product. Bamboo has a higher specific compressive strength.
The appearance of flowers in the Bamboo plant is very irregular, in fact many flowers at intervals as long as 65 or 120 years. Bamboo plant ethereal mass flowering plant. There are different hypotheses regarding the flowering of bamboo plants. Rats and rodents like the flower.
Uses Of Bamboo Plants
Water-Hyacinth
Water hyacinth is an aquatic free-floating perennial plant native to the Amazon basin. This aquatic plant can grow to a height of 3 feet. Leaves are dark green, leave blades are circular to elliptical in shape. Petiole are inflated and spongy.
The water hyacinth was introduced from its native home in South America to various countries as an ornamental plant and keep cool the ponds and lakes. Water hyacinth has a negative impact on aquatic ecosystem and its propagation need to control.
Due to its rapid reproductional ability, this plant can spread all over the .pond within a very short time. Due to the rapid growth of water hyacinths, other aquatic plants are being deprived of getting adequate sunlight and dissolved oxygen. Fishes and other animals face severe problems and succumb to death.
Aedes mosquitoes propagate in the densely grown water hyacinth plants. Besides this, a type of small snail like this plant and this snail propagate a helminth disease.
Uses of Water Hyacinth
SAL :
Sal (Shorea robusta) is a large perennial, woody, deciduous dicotyledonous economically important tree. Sal is moderate to slow-growing plant and takes 25 to 30 years to be mature.
Sal attains Leaves of sal are broad and shed most of its leaves during spring. heights of 30 to 35 m and a trunk diameter of up to 2 – 2.5 m. Leaves of sal are broad and shed most of its leaves during spring.
Importance Of Wood
Leaf:
In northern and eastern India the ury leaves of sal are a major source of the production of leaf plates and leaf bowls.
Leaves are also used for readymade food and used leaves for the food of cattle goats, cows, etc.
Gum :
Gum from the sal tree red resins in the form of gum released. From it resin is made and used in the work of wood polish and crack filler.
Resin :
Resin also used for making spirit and varnish.
Tannin :
Tannins derived from bark are used in leather industries and used as pan marshalls.
Oil :
Seed oil is extracted from seeds and used as cooking oil after refining and also used for lighting lamps, cooking, and chocolate making.
Sundari
Sundari is a type of evergreen mangrove tree. It is the dominant mangrove tree of the Sundarbans. It is a major timber-producing tree. The IUCN (International Union for Conservation of Nature and Natural resources)-has assessed this plant as being endangered.
The Sundari tree is medium size growing to a height of 15 to 25 meters. They grow in muddy places its base may wash twice by the tide. The roots are shallow and spreading and their small branches come above the soil. They bear many pores and are capable of respiration these roots are called pneumatophores.
They grow in soft soil therefore trunks develop buttresses. Some curved adventitious roots project in a curved manner from the base of the stain and penetrate in loose soil for providing mechanical strength to the plant These roots are called stilt roots.
The trunk has a few large branches and the canopy is open. The leathery leaves (covered by waxy substances) glisten, the lower surface is light green. Pink or orange bell-shaped flower. The fruit is egg-like. New seedlings came out from the seed present within the fruit.
Uses of Sundari
Spices And Plants
We like tasty cooked food. Spices is the ingredient to make our cooked food tasty. Best-quality spices are found in India. Different visitors and tourists came from different parts of the world for the attraction of Indian spices.
Indian spices include a variety of spices grown across the Indian sub-continent with different climates in different parts of the country. India produces a variety of spices many of which are native to the subcontinent.
Uses of spices :
Table
| Plant part | Name of plant use as species |
| 1. Bark | 1. Cinnamon |
| 2. Fruit | 2. Black pepper, cardamom |
| 3. Leaves | 3. Mint, cassia (Tejpata) |
| 4. Bulbs | 4. Onion, Garlic |
| 5. Rizomes | 5. Ginger, Turmeric |
| 6. Seed | 6. Mustard, Ajowan |
| 7. Buds | 7. Clove |
| 8. Floral part | 8. Saffron |
| 9. Kernel | 9. Nut |
Black Paper
Black pepper is a perennial flowering vine cultivated for its fruit. This is usually dried and used as a spice and seasoning. When dried the fruit is known as a peppercorn. Its unripe fruit is green when ripe became red and when dried became black. The dry fruit is used as a spice.
Usage—Beside make our cooked food tasty, potassium another mineral in black pepper helps to improve our stomach’s ability to digest food and promote intestinal health. Black pepper is used as a whole or in powder form. Its hot test is for Piperine.
Because black pepper is a carminative it discourages intestinal gas formation and helps in the breakdown of fat cells. Black pepper is used in cough, toothache, bleeding gum, pain in gum, and indigestion.
Cinnamon
Hope you have seen cinnamon in some sweet in food like ‘polao’ and ‘fried rice’. Cinnamon is a spice obtained from the inner bark of the plant genus of Cinnamomum. It is an evergreen tree. The term ‘cinnamon’ also refers to its mid-brown color. Cinnamon is of two types-thick bark and thin bark.
Usage :
Turmeric
You will not find anyone who have not seen turmeric. Turmeric is a rhizomatous (modified stem) perennial herb. Turmeric is native to Southeast Asia. Turmeric’s aerial stem is not visible, only leaves are visible outside.
The part use is the modified stem. Commercially turmeric is prepared from the underground yellow bulb of the plant;
The bulb (stem) of Turmeric is yellow an underground part, it may be used raw but usually, the bulb are boiled in water (for half an hour). After that, it is dried and powdered.
Usage—
Turmeric is used in most of the cooking vegetables, fish, and meat dishes. Besides, it is used for making color. Turmeric has an antibiotic role. It is used in Ayurvedic medicine. A mixture of lime and turmeric are used as medicine to relieve from bone pain due to injury.
People use it in different festivals and social occasions. Turmeric helps to prevent anemia because it reaches in iron. Research shows that turmeric is effective in controlling cholesterol level in the blood.
Cardamom:
Cardamom is a herbaceous perennial plant in the ginger family native to Southern India. It has rigid and erect aromatic leaves which form the aerial part of the plant. It is the most common of the spices whose seeds are used as a spice called cardamom. black paper is the king of spices cardamom is the queen of spices.
Cardamom is one of the world’s most expensive spices after saffron. It has a sweet burning taste and very distinct spicy odor. Cardamom is mainly of two types. Greater cardamom and lesser cardamom. Greater cardamom when dry is coppery in colour. The fruit is used as cardamom. The fruit of lesser cardamom becomes light brown when dried artificially.
Usage—
It has a special flavor. To bring taste and special flavour of dishes cardamom is used. It is also frequently used in different sweet dishes (Payes, Halua, etc.) and also in different types of sweets.
Cardamom is used in medicine of stomach-related problems, gum related problems, used as a mouth freshener, and seeds of greater cardamom alleviate nausea. Garam masala-Garam masala is a preparation of mixing of clove, cardamom, cinnamon, black pepper mace, and nutmeg.
Ginger
Ginger is a flowering perennial herb. Stem is rhizome type (modified stem). Aerial parts like narrow green leaves and yellow flowers appear annually from the rhizome. Ginger plants have been extremely popular though out Asia especially in India from ancient times used extensively for cooking and to treat cough, cold, joint pain, etc.
Use of Ginger :
It is also used in cough syrup.
Make a table of food and other things where ginger is used :
| Food Products | Use of ginger (part) |
| Other than food as medicinal value. |
Garlic
Garlic is closely related to the onion, a perennial flowering plant. Its stem is modified bulb type (bulbous plant). A round bulb of garlic consists of 6-30 small bulb-like parts These are called grates of garlic. The whole bulb is covered by a light dry covering.
Allin a sulfur-containing compound found in garlic which is mainly the compound most responsible for the “hot sensation” of raw garlic and its our. Allin is odorless when it comes to contracting with an alliinase enzyme (cut or crushed) and converting it into allicin. This is responsible for the pungent odor.
Usage: Spice: Garlic is most often used as a flavoring agent. Garlic is used with onion and ginger as a paste for the cooking of fish and meat. It is also uÿtomake tasty of some vegetable dishes. Make a jable of cooking where garlic is used as a spice.
Other usages:
Garlic has medicinal food of beneficial to value the alleviation. Garlic or anti-oxidant properties of Allicin. It is also beneficial to regulate blood pressure and blood sugar.
From ancient times, humans gathered knowledge about the medicinal properties of plants. India has a long tradition of using indigenous plants or plant parts as medicine.
Ayurvedic medicines have been documented in the ‘Atharva Veda’, ‘Rig Veda, and ‘Sushruta Samhita’ in our country. According to WHO (World Health Organization), nearly 80% of the world’s population depends upon traditional medicines for their primary treatment and most of them originate from some medicinal plants.
We come to know from recent studies that more than 20,000 plants have medicinal properties (it may increase in the coming days) of these 8500 plant species are only in Asia. At present nearly 3500 species of medicinal plants are found in our country.
Neem [Azadirachta Indica) :
Many of you have seen the Neem tree. It is a medium-sized (15 – 20 meters) first-growing evergreen tree. Neem is native to the Indian subcontinent i.e India, Bangladesh, Nepal, Pakistan, Srilanka, and Maldives. The fruit is oval to nearly roundish yellow in colour. Different parts of the neem tree i.e leaves, bark, and fruits are used for different purposes.
Medicinal Properties Of Neem
Collect neem leaves dry it keep it in your books and exercise katas. Observe the result. ‘Nimbidin’ is the main active antibacterial ingredient of neem.
Bael
Bael is the most ancient sacred tree native to India. Bael is a medium-sized deciduous tree. Owing to its hard nature bael tree has wide adaptability to adverse soil and climatic condition.
Bael has enough medicinal value because of the presence of various alkaloids (nitrogenous excretory products of plant) polysaccharides and essential oil. It also contains mucilage and pectin.
Benefits of Bael fruit
Emblica (Amlaki) : (Phyllanthus emblica)
The common name Amla is a small leafy tree that grows throughout India and bears an edible fruit.
Seeds of Amla is useful in asthma, and biliary disease.
Triphala :
Triphala is a kind of Ayurvedic combination of ‘three fruits’ Bibhitaki (bara), Amlaki (Emblica), and (chebulic) heritage. It is primarily used to maintain a healthy digestive tract. Triphala is deeply nourishing and cleansing to all tissues and is a very effective detoxifier. Triphala also benefits for the lungs, skin, and eyes.
Catharanthus
Catharanthus is a tropical plant used for medical purposes mainly. Nayantara or Catharanthus is an annual herb short sighted flowering plant. The leaves are oval the flowers are white to dark pink. The species has long been cultivated for herbal medicines and as an ornamental plant.
Medicinal properties :
Mint (Pydana):
Mint or pudina is also known as ‘Mentha’. It is a perennial herb.
Benefits :
Alovera (Aloe i/era) :
Alovera is a perennial herb succulent with long thick leaves that grows wild in tropical climates around the world and is cultivated for agriculture and medicinal uses. It is used in many consumer products including beverages, skin-lotion, cosmetics- or ointments for minor burns and sunburns though their permanent effects yet to be established.
Medicinal propirties :
It promotes hair growth prevent itching on the scalp, reduces dandruff, and condition hair. Extract of aloe vera leaves is used to reduce stress and tension.
Suppose you are sitting in your classroom—look around what you will see. Chair, benches, ack-board, chalk, duster/ teacher, your classmate’s other students. If you give a close look to the corner of your classroom—you may find one or two spiders who are busy forming their nets.
You may find some ants or a housefly. Then if you look outside the window you may see some birds, and squirrels beside some grasshoppers in the lash green playground outside your classroom.
Now you can easily classify the living and non-living things around you. Chair, table, chalk, duster etc. all are unable to move and can’t respond to any stimuli. But the teacher, your friends, spider, housefly, birds, grasses etc can either move or respond to stimuli or both.
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The former group is non-living and the latter is living—is it not right?
Living things—Why they are so?
Let’s see what are the functions usually living being do—
Respiration:
Inhaling and exhaling of air (02 – C02)
Digestion:
Intake of food and break-down of food into small parts.
Excretion:
Elimination of waste materials through urine which is produced in the body through particular organs or organs by metabolism.
Co-ordination:
(Nervous system including the brain)—Receiving stimuli and conveying ir different parts, adjusting body functions as well as making an adjustment with the surrounding environment.
Circulation:
The heart receives blood from different parts of the body and pumps to those places that help in transport.
The organs performing these functions are respectively lungs (respiration), stomach and small intestine (digestion), Kidney (excretion), Brain and spinal cord (Nervous system ordination), and Heart (Circulation).
structural similarities between the Body of organisms and building complex
The smallest structural and functional (egg of unit of the organism (body) is called a cell.
Microscope:
Cells are so small except very few (eggs of birds, Jute fibres etc.) that we can’t see it only by our naked eye. We can see after magnifying it by a tool or instrument. The tool through which we can see the cell and its parts by magnifying it is called Microscope.
A microscope is an instrument that, gives an enlarged or magnified and clear (resolution) image of an object (cell or its parts) that is not visible to the naked eye.
Robert Hooke, an English Scientist in 1665 discovered and named the ‘cell’ while examining a thin section of bottle cork under his self-made primitive Microscope.
Robert Hooke observed in this section of cork honeycomb-like many empty small compartments under Microscope. Hooke named these honey comb compartments as ‘cells’. This word cell is derived from the Latin word ‘cellulite’ which means a little room.
Robert Hooke observed the dead cells which was hollow, only cell walls where there no protoplasmic substances in them. In 1674 Anton von Leeuwenhoek made an improved microscope and observed living cells. (Human sperm cells, blood cells, protozoans etc.) Robert Hook’s work was published in the book “Micrographia” in 1665.
Microscopes are a high-resolution and magnifying instruments that are used for observing fine structures of very minute objects.
Two common type of microscope are usually used —
Light Microscope is of two types —
1. Simple Light Microscope or Binocular Microscope.
It is simple in structure and very easy to use. It has only one ocular lens, binocular eyepieces. It is usually used during dissecting of plants and tiny animal parts dissection. So it is called a dissecting microscope. It can magnify or enlarge 15 – 20 times image of the original specimen.
2. Compound Light Microscope.
Two or more lenses are usually used in this microscope — ocular lens, objective lens and sometimes with condenser lens. In this type of Microscope lens combined together and their magnification power range from 300 to 4000 times.
3. Electron Microscope
This is a large and complex instrument of very high magnification. In this Microscope beams of electrons are used as a source of illumination of objects instead of light and electro-magnets are used in place of glass lenses. The magnification power of this type of Microscope is 50,000 to 300,000 times. . The image of the object is obtained on a photographic plate or in a screen.
Viruses, bacteria, various complex structures of cells (mainly cell organelles), and different cellular components (such as DNA, RNA, protein etc.) are usually observed through Electron Microscope. Electron Microscope Through this microscope detail and complex structure of objects can be seen and understood.
In the living world some organisms such as Amoeba (Protozoa), Yeast (Fungi), and Vibrio cholera (bacteria, germ of cholera) consist of single cells, they are called unicellular whereas plants and animals are more complex organisms and consist of many cells, these are. called multicellular organisms.
In unicellular organisms all activities are carried out by the same cell, whereas in multicellular organisms the cells show division of labour i.e. a different group of cells perform different functions. Multicellular organisms can adapt better to the changing environment.
All cells whether these are of unicellular or multicellular organisms carry out certain functions – such as respiration, nutrition, growth, reproduction, excretion etc.
If you observe different sections of different parts of plant and animals under a microscope, you will find cells of these sections not alike. They are of different shapes and size. Cells may be oval, elongated, rectangular, columnar, filamentous, polygonal etc.
In multicellular organisms, the shape and size of the cells depend on their position and metabolic activity or nature of the function, such as cells of squamous epithelial are flat, and polygonal whereas the inner lining cells of the intestine is columnar (pillar-like).
Some Plant cells of different
Some cells (animal) and their shape :
There are many varieties in cell structures both in animals and plants. Some animal cells structure are discussed here :
Amoeba :
Amoeba is a free-living unicellular organisms. Amoeba often changes its shape, and small finger-like cytoplasmic out-growth or projections come-out from its body known as pseudopodia (pseudo = false, poda = leg) at the time of locomotion and food capture. Some human WBC (leucocytes) also form (produce) pseudopodia during phagocytosis and can change their shape.
Phagocytosis is the process of engulfing of micro-organisms (pathogen) or foreign bodies surrounding it, by producing pseudopodia.
Human RBC are circular and flattend at the centre (disc-shaped). Its shape helps RBC to carry more oxygen and can move easily through blood vessels of different diameters.
Human RBCs lack of a nucleus, mitochondria, ER, ribosome and centrosome. Therefore, it has more space to hold haemoglobins (the iron-containing respiratory pigment) and its own oxygen consumption is very low due to lack of organelles. Thus it carries more oxygen (02) to the tissue cells.
Muscle cells are elongated or may be spindle-shaped (non-striated). Both ends of it are tapering. Voluntary (Striated or skeletal) muscle cells are long cylindrical multinucleated (many nuclei). Within this cell numerous fine contractile thread-like structures are present, known as myofibrils.
This structure helps in contraction and relaxation. This contraction and expansion property of these cells helps in movement, passing things in different body canals such as food passing in the alimentary canal, air in the trachea, opening and closing of apertures, beating of heart etc.
Nerve cells (neurons) are usually elongated with some branches. It’s extended star-shaped or rounded shaped part is known as the cell body. A neurone or nerve cell has two types of processes—branched dendron and usually unbranched comparatively long part axon.
Nerve cells receive stimuli (both external and internal) like light, sound, touch, heat, pressure etc. and transmit the message to different parts of the body. Nerve cells or neurons is the structural and functional unit of the nervous system. Which coordinates between the external and internal environment of animals.
Besides this more than two hundred types of cellular varieties are observed in vertebrates.
Plant cells also are of different shapes such as oval, round, hexagonal, polygonal, rectangular, and elongated tube-like (xylem, phloem) cells associated with transport. Parenchyma cells of roots, and stems, are generally oval or spherical, schlerenchyma cells are elongated and have a hard cell wall.
The cells of the apical region of the root and stem are usually in shape and a have the power of division constantly. The cells associated with the transport of water and food are usually cylindrical in shape.
Table: Try to complete the table (one example cited).
Very few plant and animal cells are visible to the naked eye like eggs of birds, the fibre of Jute, and Acetabularia – a type of algae (10 cm height). However, the majority of cells are visible only with a microscope because they are only a few micrometres or microns in diameter.
A micrometre or micron (p,m) is one-thousandth of a millimetre. The size of the majority of cells are of 5 – 10 microns. In a single full stop, O I micron area of 400 cells may accommodate. Then you can imagine how small the cells are.
The shape of cell may change, like RBC can change shape when it moves through blood vessels, and cancer cells change the shape of the cell. Cell shape also changes during cell division. WBC also change shape. Some WBC also changes its shape.
Do you think the cells of a Blue whale or elephant is much larger than the cells of rat? The answer is no. The size of cells not depend on the size of the organism. What is the reason of cells to change their shape—Cell change their shape mainly due to their specific function and location.
⇒ \(1 \mathrm{mp} \text { micron (micrometer) }=\frac{1}{1000} \mathrm{~mm}=0.001 \mathrm{~mm}\)
⇒ \(1 \mathrm{~nm}(\text { nanometer })=\frac{1}{1000000}=0.000001 \mathrm{~mm}\)
⇒ \(1 \mathrm{~A}^{\circ}(\text { Angstrom })=\frac{1}{10000000}=0.0000001 \mathrm{~mm}\)
The number of cells in multicellular organisms usually is correlated with the size of an organism such as larger the size more the number of cells. In a normal human being the number of cells is estimated at 100 trillion (1014) approx.
Smallest cell— Mycoplasma leidlawii
Longest plant cell— Cells of the bark of Reme tree
Longest animal cell— Neurone (Nerve cell)
Largest animal cell— the egg of Ostrich Largest plant cell— Acetabularia
Different physiological functions and Specialisation of cells
Typical cell range from 5-50 micrometres
Plants also perform different physiological functions, such as—
Relationship of Body-organ-tissue-cell
The shape of the cell varies with the functions it performs. Few examples-
Now just think of your body which is consists of many organs such as the heart, liver, lung, ovary/ testis etc. which are the part of different systems such as circulatory, digestive, respiratory, reproductive etc.
Each organ consists of many tissue like the heart consists of muscular tissue (cardiac muscle) connective tissue, epithelial tissue etc. And each tissue consists of many cells of more or less similar structure and origin and also perform the same function.
The structural steps of a multicellular organism are—
organism→ organ-system → organ→ tissue → cell.
Tissue –
A group of cells usually similar in structure and origin that work together to perform a particular function is called tissue.
Plant tissue are of mainly two types
Meristematic tissue :
Thin-walled living group of cells having active cell division capacity.
Location :
These tissues are present in the apical parts of the plant which is responsible for continuous growth.
Function :
Mature cells with thin to hard cell-wall which are not capable of cell division.
Location :
Root, stem and leaves.
Function :
Different type of Animal tissue and their functions (Major animal tissue)
Connective tissue contains two types of fibres—
Fat cells ( = adipocytes) store fat in the form of large fat globules.
Tendon :
Connective tissue cord-like structure (bundles of parallel run white fibres), non-elastic, join the muscles with bone.
Three types of muscles-striated. (skeletal or voluntary), nonstriated (smooth or involuntary) and cardiac.
Myofibrils:
muscle cells contain many highly contractile (myosin) parallelly arranged threads are called myofibrils. Muscular tissue is formed of elongated and highly contractile muscular cells. Muscle contract and relax to make the movement of the body possible.
Functions :
Nerve cells or neurons and some supporting cells form the nerve tissue. Neurone is the structural and functional unit of the nervous system.
Function :
The cell is defined as a mass of protoplasm (gely-like matrix) bounded by the plasma membrane structural and functional unit of an organism.
The major two types of Eukaryotic cells are Animal cells and Plant cells.
Different structural parts of Animal cell
Cell membrane
Each cell is bounded by a thin elastic living membrane, called the plasma membrane or cell membrane. Plasma-membrane is made-up of mainly lipids (fat) and protein.
Though this membrane has some pores but it is a selectively permeable membrane because it allows water and some selective substances (minerals etc) into the cell and out of the cell. The exchange of materials depends on the size and its nature.
Functions Of Cell membrane:
Protoplasm :
The substance inside the cell is collectively known as protoplasm.
Cytoplasm :
The jelly-like semi-liquid (colloidal) substance of the cell except the nucleus is called the cytoplasm.
Cytoplasmic organelles are present within this. This is the actual place of different metabolic functions of the cell.
Protoplasm = Cytoplasm + Nucleus
Cytoplasm = Protoplasm – Nucleus
The dense rounded or oval structure usually present in the middle of the Cytoplasm is called the nucleus. Human RBCs have no nucleus.
The nucleus is the controlling centre of all cellular activities (biochemical) so it is called the “brain of the cell”. The nucleus is surrounded by a porous membrane (double-layered) called a nuclear membrane which separates the nucleus from the surrounding cytoplasm.
The dense sap present inside the nuclear membrane is known as nuclear sap or nucleoplasm. A fine thread-like structure present inside the nucleus is known as Chromatin. Chromatin is formed of DNA (Deoxyribonucleic acid) and protein.
DNA is a macromolecule consisting of two fine threads which coiled together (double helical structure). The chromatin is called, chromosome during cell division (at that time it is thicker).
The chromosomes COntain Stretches of DNA which carries information for protein synthesis. This functional part of DNA is known as a gene. The characteristics of parents pass to offspring through genes.
For this reason, the ‘gene’ is called the hereditary unit (hereditary material). within the nucleus present a dense rounded structure where ribosomes are synthesized is known as a nucleolus.
The functional part of DNA of a chromosome which transmits hereditary characters from parents to offspring.
‘Pro’ = primitive, ‘Karyon’ = nucleus, ‘Eu’ = advance
The function of the Nucleus :
Mitochondria (Singular – Mitochondrion) Mitochondrial DNA is their own DNA. They are maternally inherited (come from the mother). Mitochondria are small and usually rod-shaped and may be rounded or oval scattered and distributed through out the cytoplasm. Each mitochondrion is bounded by two membranes—outer and inner.
Many finger-like projections (out-growth) come-out from the inner membrane, these finger-like projections are called cristae. Within the cristae present some tennis bat-like structures, known as oxysome.
The ground substance present inside the mitochondria is called a matrix, the matrix possesses different enzymes, DNA, RNA, ribosome, and proteins. Different enzymes are also present in the inner membrane. They are involved in energy production.
Function Of Mitochondria:
Mitochondria provide energy for the vital activities of living cells for this reason mitochondria is known as the “Power House of the cell”. Cellular respiration occur within this organelle.
The endoplasmic reticulum is a network of membrane-bounded tubular structures of different shapes and size. It usually forms a net-work between the plasma membrane and nuclear membrane.
Sometimes ribosome is attached to it (ER) then it is called rough ER (RER) and sometimes without ribosome attachment then it is called smooth ER (SER). Rough ER (RER) with the help of ribosome manufacture protein and smooth ER (SER) helps in the manufacture of fat molecules or lipids.
Golgi bodies are membrane-bounded organelles present near the nucleus formed from ER. Golgi bodies consist of .tube-like structures (cisternae), large vacuoles and small vesicles. Tube-like structures (cisternae) are usually arranged in parallel to each other. In plant cell golgi bodies are known as dictyosomes (distributed scattered).
Function Of Golgi bodies:
Helps in secretion/storage, transportation and formation of other cellular organelles like lysosomes. Scientist Camillo Golgi first describes Golgi bodies.
Lysosome :
Lysosome is a single membrane-bounded sac-like small spherical vesicle. Lysosome originates from golgi bodies and contains enzymes (hydrolytic) which help in intracellular digestion.
Lysosome is polymorphic (have different forms). Lysosome is found in animal cells and meristematic cells of a few plants. Lysosome helps in digestion as well as destroys pathogens (bacteria) and old cellular substances.
Excessive lysosomal activities (secretion) lead to cancer. Sometimes lysosomes digest it’s own organelles and destroy their own cells, hence lysosomes are called ‘suicidal bags’.
Ribosomes are very small, rounded cell organelles not bound by any membrane. Ribosome has two subunits (larger and smaller). Ribosomes are found freely in the cytoplasm as well as attached with some organelles like the endoplasmic reticulum, and nuclear membrane.
Ribosomes are also seen inside of some organelles like mitochondria and chloroplast. Ribosomes are composed of ribonucleic protein (ribonucleic acid and protein). The main function of ribosomes is protein synthesis. (Workplace for the synthesis of proteins).
Centrosome is a distinct region of the cytoplasm close to the nucleus. It ‘usually has two centrioles which are arranged at a right angles to each other. The area surrounding the centrioles is known as the centrosphere.
The centrioles are membrane-less cylindrical, hollow structures made of microtubules (hollow straw-like structures).
Functions Of Centrosome:
Study the plant cell (Activity) / animal cell (activity)
If you observe a plant cell under a microscope (see activity). You will find some new parts which you have not noticed in an animal cell. A rigid covering (cell wall), oval or rounded, pigmented organelle (plastids) and some small to large space (vacuoles) in the cytoplasm.
Cell wall :
In plants, cells have an additional protective wall outside the cell membrane or plasma membrane. This relatively thick, rigid, non-living covering of plant cells is called the cell wall. Cell wall- is permeable and is made up of cellulose (A type of carbohydrate).
The cell wall provides extra protection to plant cell (which much require as the plants are usually stationary). Cell wall provide a particular shape to the cell and prevents drying up (desiccation) of cells. Cell walls have a number of pores through which the exchange of various substances occurs.
It also maintains osmotic pressure.
The difference you can notice between Cell wall and Cell membrane.
Why the cell wall is so strong?
Cell wall is so strong Because of:
The temperature in nature is much variable often increases and decreases. Humidity and wind flow also increase or decrease. More over plant can not able to move (stationary). So they have to face much unfavourable conditions. Therefore they need hard cell wall.
In plant cell double membrane bounded round or oval-shaped scattered distributed cytoplasmic organelle is plastid. Most of them possess different types of Pigments. The green pigment (chlorophyll)containing plastids are called chromoplasts
Various other coloured pigments (red, orange, etc.)the colourless plastids are containing plastids are called chromoplasts and the colourless plastids are called leucoplasts (devoid of chlorophyll and other coloured pigments).
Chloroplast have two distinct regions—’grana’ and ‘stroma’ (the matrix). Granum (singular) is a pillar¬like structure and composed of the discoid sac (Thylacoids) containing chlorophyll or other pigments. The homogeneous matrix in which grana are embedded is called the stroma. Nucleic acid (DNA, RNA), ribosomes and different types of enzymes are present in stroma.
Function Of Chloroplast:
Chloroplast helps in making food (photosynthesis).
Chromoplast:
Provide colour to different parts of the plant.(flower, fruits, some leaves) and help in the pollination and dispersal of seed and fruit.
Leucoplast:
Helps in the storage of food (usually present in root cells).
Chloroplast:
Green plastids have green pigment, chlorophyll. Chloroplast present usually in the green leaves and green parts of plants (stem, fruits etc.) Helps in photosynthesis (food production).
Chromoplast:
Variously coloured plastids (containing different types of pigments like- red, orange, yellow etc.). Usually present in flowers, fruit and parts of the leaf.
Leucoplast:
Colourless plastids, not bearing pigments. The main function is storage (carbohydrate, fat, protein).
The small and large fluid-filled (sap) space in the cytoplasm of cell is called a vacuole. In animal cell vacuoles are smaller in size and lesser in number than plant cells.
In mature plant cells the major portion is occupied by vacuoles. In some plant cells (Spirogyra and many others) this type of arrangement (large vacuoles) pushed the cytoplasm to the periphery as thin layer. This is called Primordial utricle.
Tonoplast:
It is a membrane separating a vacuole from the surrounding cytoplasm.
Vacuoles play an important role to maintain water balance, internal pressure, osmotic pressure, and storage of different substances including waste products. It also helps in cell growth.
Cell-organelles—their location and specific functions
Organisms live in an environment. The physical and biological condition in which an organism lives and with which it interacts is called the environment.
An organism cannot survive in all environments, such as a Polar bear or a Penguin used to live in a very cold environment would not survive in a desert. Similarly, Camel and Ostrich would not survive in the polar regions. It is clear that the environment in which an organism lives must suit its needs.
Environment: The surroundings of organisms in which it lives and interacts.
Habitat: The place where an organism lives.
Living organisms adapt to different environments for their survival. The organism which cope well with a particular environment such as dry desert, cold pollar region or aquatic (fresh or saline) condition need to adapt themselves for the condition. Several structural and functional diversities are observed in the body of living organisms while they try to adapt in
different environment.
The changes that occur in the body of the organisms are also observed in the cellular level. Let’s see some of the adaptations in the cellular level of some organisms who are living in different environments.
As mentioned earlier that an atom usually consists of an equal number of protons (positive charges) and electrons (negative charges) and is, therefore, electrically neutral.
If, however, the charges are not balanced, an electrically neutral object becomes electrically charged (either positively or negatively charged depending upon the number of protons and electrons).
Such a charging can be done by any of the following methods, like
Read and Learn more WBBSE Notes For Class 8 General Science And Environment
For example, when a plastic comb is rubbed with dry hair or a plastic refill is rubbed with polythene, the objects (comb and hair, refill and poly-then) acquire electric charges. The objects are then called electrically charged objects.- Let us see the following figures to have an idea how charging is done.
How do the charges transfer?
Charges Transfer As follows
Generally, electric charges can be transferred from one charged body to an uncharged body, when they come in contact with one another through a metal conductor so that the electric charges jump from the charged body to the uncharged body till the charges on both of the bodies are equalized. The process is known as charging.
On the other hand, the charged bodies lose their charges through air, vacuum or any other gas. The process is known as discharging. An electric spark (which we see at electric switches when they are being turned off) is an example of an electric discharge.
Natural current and natural potential difference :
Throughout the day and night, all over the earth, there is a continuous flow of electric current flowing downwards in the air. The current is very feeble and we never feel it around us. The current is known as natural current.
What is the source of this current?
Source of this current
Actually, there is a potential difference of about .400,000 volts existing between the earth and the atmosphere around 50 km above the earth’s surface. In fact, the charged particles (various ions, other minute charged particles) in the airflow due to such a massive potential difference (Which is known as natural potential difference) giving rise to the flow of natural current.
Lightning occurs because of the transfer of massive electric charges from cloud to cloud, or from one part of the cloud to another part, even from a cloud to the ground.
Let us explain lightning in terms of charges produced by rubbing. It is the fact that the air currents move upward while the water droplets floating in the air move downward. Such vigorous movements separate out electric charges within the clouds, such that, the negative charges accumulate in the lower portion of the clouds while the upper portion carries positive charges.
These charges keep building up and initially, they can not flow through the air, as air is an insulator. But when the magnitude of accumulated charges becomes extremely large, the air is no longer able to resist the flow of the charges. Negative and positive charges meet, i.e., electric discharge occurs.
The electric lightning is accompanied by large amounts of electric current and very very high temperatures. Both discharges occur between two or more clouds, or between the earth and the clouds, and we see streaks as lightning. how the accumulation of charges leads to lightning. show respectively how sheet lightning and for lightning occur in the upper sky.
Lightning usually strikes, tall towers, buildings and trees. In this article, we are to discuss about some safety measures to be adopted during a thunderstorm.
Famous scientist Benjamin Franklin proved in 1752 that lightning and the spark which see in our woollen or polyester clothes are essentially the same phenomena.
To find a safe place :
A lightning conductor is a safety device used to protect tall towers and buildings from the damaging effect of lightning. It comprises of a metallic rod, taller than the building, running from top to bottom along the outer wall of the building. The upper end of the rod is kept out in the air, while the lower end is buried at least 5-6 ft deep in the ground.
It provides a direct, easy path for the transfer of electric charge to enter the ground without passing through the building. Even if lightning strikes the house, no damage occurs, as the high voltage is transferred to the earth through the easy path of the lightning conductor.
All of us more or less have a feeling of disease. We are very much familiar with the term -“Disease”. The disease is a condition of the body or part of it in which functions are disturbed or shown some abnormalities.
When a large number of people (hundreds or thousands) die at the same time or in a short period of time, such as within a few weeks, or months or in every year due to break out of fatal diseases, then this type of disease is called an epidemic.
Sometimes you have noticed that many people die of Diarrhoea, Cholera, Dengue, Black fever or SARC then this disease is declared as an epidemic into that area.
Now the question is why particular diseases turn into an epidemic.
A disease is called an epidemic when it spreads rapidly among a large number of people in a community at the same time period.
Before understanding it we have to find the answers of some questions :
If you find the answers of these questions you will understand why a particular disease has become an epidemic.
Types of Epidemic :
Knowledge about various types of epidemics and the condition (such as environment, host, population etc) under which they are occurred can be helpful in managing epidemics.
This type of epidemic is caused by a single source of infection of the diseases causing agents for example poisoning of food, water (Minamata disease), or air (Bhopal MIC gas tragedy). A very common example of this type of the epidemic is causing of food poisoning due to the consumption of contaminated food in the feast.
Sometimes you may notice that a good number of people have been transferred to the hospital after taking contaminated Biryani or other types of food like Lassi etc.
This type of epidemic is generally of infectious origin. In this type of disease-causing agent is directly transmitted from one person to another. This type of epidemic is more likely where a large number of susceptible individuals gather such as at fairs, festivals, playgrounds, meetings etc.
Examples of these types of diseases are Small Pox, Measles, Influenza etc.
Change of lifestyle, less physical activity, and intake of frequent junk-food, causes some diseases like—hypertension, heart disease, diabetes, mental diseases, obesity, lung cancer, etc. These are non-infectious diseases, that break out as epidemics known as non-infectious epidemics.
Besides these major types of epidemics, there are some other types of epidemics on the basis of time periods or seasons.
1. Cyclical epidemics :
Some epidemic diseases break out in cyclic order, such as day, week, month or even years.
For example, it has been reported that before the discovery of vaccines of Measles generally occur in intervals of 2-3. years, Influenza in the intervals of 7—10 years.
2. Seasonal epidemics :
Some diseases have a close relationship with the seasons of the year. An epidemic which occurs in particular seasons are known as a seasonal epidemic.
For example, Influenza, Pneumonia, and upper respiratory tract infections are common in the winter season whereas diarrhoea and intestinal infections are more common during the summer and rainy seasons. Measles and chicken pox usually break out on the onset of spring.
Different types of epidemics and their Characteristics :
| Epidemic type | Characteristics | Example |
| 1. Common source epidemic | 1. Single-source infection | 1. Food poisoning (by some toxication) Water Poisoning, Air Poisoning etc. |
| 2. .Propagate epidemic or epidemic from infection. | 2. Infectious origin, transmitted from one person to another directly or indirectly | 2. Influenza, Malaria, Smallpox, Measles etc. |
| 3. Non-infectious epidemic | 3. Change of lifestyle, food habits, pollution etc is the cause of the epidemic. | 3. Lung cancer, Heart disease, Diabetes, Obesity etc. |
| 1. Cyclical epidemic | 1. Occur in cycles of time-Period. | 1. Influenza, Measles |
| 2. Seasonal epidemic | 2. Usually breakout in particular season | 2. Diarrhoea and intestinal infections during the rainy season. |
An endemic disease is a disease which has regular occurrence in a given geographic area example, cholera.
Cholera :
Germ :
Cholera is caused by tiny germ (bacteria) Vibrio cholera.
Entry of germ :
This germ (V. cholera) enters the human body through contaminated water and food and through not properly washed contaminated utensils and unwashed hands. Fly also plays a role to contaminate food. An unhygienic environment favours bacteria to growth.
Symptoms :
In cholera severe but painless diarrhoea flowed by sudden vomiting. Loss of water (body fluid) occurs which leads to dehydration of the body. It losses the equilibrium of sodium and potassium and other salts of the body. Other symptoms are muscular cramps, and skin becoming cold and wrinkled.
Prevention :
Dehydration can be prevented by giving the patient ORS or salt-sugar solution. Cholera is a deadly disease if not treated properly patients may die. A hygienic environment should be maintained.
ORS = Oral Rehydration Solution
ORT = Oral Rehydration therapy.
Malaria
The world ‘Malaria’ means “bad air”. Malaria fever is one of the oldest most dreadful diseases of mankind. Even now when science and medicine has so advanced about half a million people die every year in the world by malaria.
Germ :
PlasmodiumThis disease vox is caused. falciparum by a tiny and other species of genus Plasmodium. Plasmodium spreads by female Anopheles mosquito (vector) from an infected person to a healthy person. 25th April is observed as World Malaria Day.
Entry of germ :
Plasmodium enters into the mosquitoes body during blood sucking from infected persons and then are transmitted to a healthy person’s body through saliva injected by the mosquito before sucking blood from that person (Some development of Plasmodium also done inside the mosquito’s body therefore Anopheles mosquito is known as a vector).
Malaria is the most important of the transmissible parasitic disease over 90 million cases occur each year.
Carriers or vector
Though vector and carrier have some differences, you will know it in higher classes. These are those living organisms that spread the germ (Pathogen) from an infected person to a healthy, person. (Some times development of some stages of life cycle of the germ occurs inside them). Vector (example, mosquito), but when direct transmission—carrier (example, house fly).
Symptoms :
The main symptoms of malaria are periodic attacks of shivering followed by high fever (up to 105°F), headache, and muscular pain are also common. When the temperature of the body drops patients sweat heavily. In persons suffering from malaria for a long time the spleen and liver become enlarged. The attack of malaria increases during the summer and rainy seasons with the increase of mosquitoes.
Prevention :
Malaria can be prevented if we able to control its vector, such as, the Anopheles mosquito. Malaria may be fatal if not treated properly
Germ:
Dengue is another fatal mosquito-borne Viral (Flavivirus) disease.
Entry of Germ :
Aedes Egypt mosquito carries the germ (Flavivirus) of dengue from an infected person to a healthy person. Dengue fever is also known as “break-bone fever” for its joint pain-causing features.
Symptoms :
Symptoms of dengue fever are high fever, headache, joint pain, lowering of platelets count and WBC (White Blood corpuscles), and sometimes rashes come out in the body.
Prevention :
Plenty of water to be taken and the patient should be under proper treatment and rest. Prevention from a mosquito bite.
Dengue spread to more than 100 countries in Asia, the Pacific, the Americas, Africa and the Caribbean islands. According to WHO (World Health Organization), nearly 50—100 million people are infected by Dengue in every year
Germ :
Plague Is a bacterial disease transmitted by rat fleas (Xenopsylla coreopsis). The bacteria responsible for the plague is Yersinia pestis.
Entry of Germ :
Rat fleas leave the rats (plague infected) that die of Plague and bite human beings and infect the person. This disease can be transmitted by various other means also such as sneezing, and direct body contact. Plague germ be spread through the air.
Symptom :
The main symptoms of plague are high fever, extreme weakness, enlargement of lymph glands, vomiting tendency, headache, lung infection, blood clotting, and blood comes with cough. The plague epidemic in Europe in 1347 was so severe that the population of the continent was reduced to one-third.
Prevention :
This dreadful disease can be avoided in a great extent by an awareness of cleaning the environment and can be controlled by prompt and proper treatment. In 1899 a devastating plague broke out in Calcutta (now Kolkata). Sister Nivedita with her team took a great role to fight against this disease. Waldemar Haffkine (1897) invented a vaccine of the Plague in Bombay (Now Mumbai).
Germ :
Smallpox is a highly infectious viral disease also known as “Red plague”. Variola virus is the causative agent of smallpox.
Entry of germ :
Before the invention of the vaccine of smallpox, it was so a deadly disease that ruined many civilizations. It spread through air. Most infections are caused by body contact.
Symptoms :
Infection occurs in the veins and venules of the skin, in the mouth, in the throat may be in other organs. Affected body parts get covered with liquid-filled blisters. Pockmarks after drying leave permanent marks on the skin. In many cases, vision of the patient have been affected. Initially, fever, body aches, headache, and rash appear 48-72 hours after initial symptoms.
Edward Jenner introduced vaccination against smallpox for the first time. He used the cowpox virus to create resistance power in the human body against smallpox. The earliest evidence of smallpox is found in the ‘Egyptian mummies’, people who died some 3000 years ago.
Prevention :
Now this disease has almost been eradicated from the globe after the discovery of the vaccine.
Germ :
Kala-azar is commonly known as ‘Dumdum fever’ or ‘Black fever’. Kala-azar is caused by tiny unicellular protozoa – Leishmania Donovan. Sand-fly is the carrier of Leishmania. Germs spread by the bite of sand fly from the infected person to a healthy person.
Symptoms :
Symptoms of the disease are continuous fever, loss of appetite and weight, fatigue, anaemia, and enlargement of the spleen and liver. In 1901 British physician Lishman first noticed the germ. Charles Donovan confirm it. So the name of this germ is Leishmania Donovan.
Indian (Bengali) Scientist Upendra Nath Brahmachari invented the medicine of Kala-azar. He was nominated for the Nobel prize though he did not get it.
Prevention :
Now, this disease is curable and can be controlled by proper treatment. A clean environment also helps to control the disease. Kala-azar acquired its name because of patchy muscular darkening of the skin caused by deposits of melanin (a pigment), these develop later on in the disease. Patches are most marked over the forehead and temples and on the mid-abdomen.
Many of you have an experience of diarrhoea. Diarrhoea is the passing of loose stool at frequent intervals.
Germs :
Various agents may responsible for diarrhoea like protozoans, bacteria, viruses, food poisoning etc.
Entry of Germ :
From recent studies, it has been found that the most common diarrhoea-causing virus is the Rotavirus. This virus is normally spread by the faecal-oral route. Contaminated mainly through water and contaminated food.
Symptoms :
During diarrhoea body loses water, it leads to dehydration of the body. The skin, tongue, and inner parts of the mouth became dry, patient may also have fever, stomach pain, vomiting tendency, and weakness. Sometimes blood appears in stool. Salt and acid-alkali equilibrium of the body is disturbed.
Preventions :
Frequent intake of ORS, as well as [ORS = Oral rehydration solution], salt-sugar solution, helps to maintain water-salt balance. Diarrhoea can be controlled by drinking pure water and contamination-free food.
Personal hygiene and community hygiene to be maintained to check this disease. A good percentage (%) of cases may be checked by washing of hands before taking food.
SARS (SARS = Severe acute respiratory syndrome)
Germs :
SARS is a deadly and highly infectious viral disease. SARS was the first broke out in Asia in 2003. Then it spread to Europe and America.
Entry of Germ :
It enters into a healthy person’s body from infected persons through air, sneezing, coughing etc.
Symptoms:
Symptoms of SARS is high fever, severe headache, including muscle aches, sometimes diarrhoea, in late stage shortness of breath, and dry cough with a high fever.
Prevention :
Personal hygiene, and avoid inhaling contaminated air. If not treated properly patient may die. The use of a mask covering the nose and mouth is effective. It is an airborne viral disease.
Germs :
Tuberculosis is caused by the bacteria Mycobacterium tuberculosis. Though in tuberculosis mainly the lung is affected but it may occur in other parts of the body, such as bone, lymph glands, intestine etc.
Entry of germs:
Tuberculosis is a highly infectious disease and is transmitted by air from one person to another person infected by droplets released through coughing, sneezing, and spitting by the patient.
Symptoms Of Tuberculosis :
Symptoms of Tuberculosis include continuous mild fever, sweating at night, loss of appetite, fatigue, weight loss, and late-stage blood in cough, and chest pain. TB can be prevented with proper care and treatment.
Preventions For Tuberculosis :
This disease now can be cure completely by using a continuous specific drug.
DOTS (Directly Observed Treatment short course) is a popular treatment and children should be immunized with BCG (Bacille Calmitte Guerin) vaccine. According to WHO India has the highest number of TB cases reported in 2016.
Germs :
Hepatitis is mainly a viral disease of the liver. Hepatitis are of five types— Hepatitis A, B, C, D, E. It is an inflammatory condition of liver. Hepatitis may also be caused by drugs, alcohol or certain medical condition.
Entry of germs :
Among these types hepatitis A and E infections are caused by contaminated water and food (faecal oral route) and the other three types i.e. Hepatitis B, C, and D by body fluid and blood.
Symptom :
Due to liver infection liver cells are damaged, releasing yellow pigment— ‘bilirubin’. WHO has declared 28th July as World Hepatitis Day.
General symptoms of hepatitis is yellowing of the skin and eyes, temperature, fatigue, general weakness, loss of appetite, nausea, vomiting tendency, and stomach pain. This condition is referred to as ‘Jaundice’.
Prevention :
Hepatitis is dangerous if not treated properly. Adequate rest and proper treatment is very much needed for hepatitis patient. About 250 million people globally are thought to be affected by hepatitis C and while300 million people are thought to be carriers of hepatitis B.
Germs:
It is a highly contagious viral disease (Myxoviruses) mainly infected the respiratory tract (nose, throat arid lung). Besides common influenza different other types of flu are found, among them swine flu and bird flu deserve special attention. Influenza occurs more commonly in the colder months and colder region.
Entry of Germ :
Influenza is spread easily from person to person contact and by droplet infection via coughing, sneezing or talking. H1N1Swine flu is an influenza virus that was found in April 2009. It causes illness in people worldwide (Pandemic). Many people die of this disease.
symptoms Of Influenza Or Flu :
The common symptoms of influenza on set of chills, discharge from nose, sneezing, fever, headache, muscular pains, joint pain, coughing, general weakness.
Prevention Of Influenza Or Flu :
Personal hygiene, adequate rest, and plenty of water intake relieve patients, it usually stays 3-7 days.
Germs :
AIDS is a fatal viral disease. It causes by the retrovirus known as Human Immuno¬deficiency virus (HIV).
Symptoms Of AIDS :
AIDS virus attacks human WBC (White Blood cells) particularly lymphocytes (T4 helper cells) and destroys the self-defence mechanism or human body immunity.
AIDS patients are prone to many other diseases such as tuberculosis, influenza, diarrhoea, fever, skin disease and many other secondary problems as the body’s immunity power weakens or is destroyed. AIDS spreads by sexual contact, blood transfusion, and the use of contaminated syringes.
Entry of Germ :
AIDS is transmitted through blood, (during blood transfusion), or through cuts, if come into contact with an infected person blood or body fluid (mucous, vaginal fluid, siemens etc) or through infected needles. AIDS virus also can be transmitted from mother to child during pregnancy.
Prevention Of AIDS :
As there is not yet any direct medicine to cure AIDS, prevention is the best method to combat this fatal disease. Social awareness to be developed from every corner.
What Is the basic difference between an epidemic and a Pandemic
Basic difference between an epidemic and a Pandemic
An epidemic occurs when an Infectious disease spreads quickly and affects many people at once In at a short or moderately large area. While pandemic is a global outbreak of disease that kills millions of people in larger areas.
For example—the epidemic of SARS killed 800 people in 2003, while the Spanish flu pandemic killed as many as 50 million people in 1918. Asian influenza pandemic that killed 2 million people In 1957. Cholera In early 19th century.
| Some Days to be remember | |
| 4th February | World Cancer day |
| 24th March | WorldTuberculosis day |
| 7th April | World Health Day |
| 25th April | World Malaria Day |
| 28th July | World Hepatitis Day |
| !st December | World AIDS Day |
Contaminated disease Complete the table (One example given)
| Name of the Disease | Responsible germ/Causative agent | Types of germ | Mode of Transmission | Prevention |
| 1. Cholera | Vibrio cholera | Bacteria | Contaminated by water, food | Personal hygiene, pure water and not taking any contaminated food. |
| 2. Malaria | ||||
| 3. Dengue | ||||
| 4. Plague | ||||
| 5. Influenza | ||||
| 6; Tuberculosis | ||||
| 7. Kala-azar | ||||
| 8. Hepatitis | ||||
| 9. SARS | ||||
| 10. AIDS | ||||
| 11. Diarrhoea |
The epidemic of non-infectious diseases
| Food habits and lifestyle | Symptom/ diseases |
| 1. Excess food intaking,. Junk food intaking, less physical work •. | 1. Obecity 2. Diabetes 3. Heart Disease |
| 2. Excess fat Intake, alcohol consumption | 1. Fatty liver 2. Heart disease |
| 3. Irregular food habits, Junk food, intake | Heart disease, gastric ulcer. |
Carbon And Carbon Compounds
Carbon and its compounds are widely distributed in nature both in a free state and in a combined state. In the free state, carbon occurs as diamond, graphite, coke, coal, gas carbon, etc.
And in the combined state it occurs as minerals e.g. limestone (CaC03), marble (CaC03 ), dolomite (MgC03.CaC03 ), calamine (ZnC03 ), magnesite (MgC03 ), siderite (FeC03 ), and in the gaseous state as carbon dioxide (C02 ), LPG, CNG, natural gas, etc.
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It is the chief constituent of all living organisms. It is present in carbohydrates, fats, proteins, cellulose, vitamins, hormones, enzymes, DNA, RNA, etc. Besides these, it plays important role in providing clothing materials like cotton, silk, nylon, rayon, jute, etc.
And also provides different medicines example quinine for malaria, penicillin for pneumonia, Chloromycetin for typhoid, etc. and provides mostly used paper, soap, perfumes, pigments and so on.
Carbon Cycle
It is the continuous circulation of carbon from the ‘environment’ through organic and inorganic substances, and then ‘back to the environment’ such that the concentration of carbon remains the same in the environment.
Steps involved in the carbon cycle :
1. Removal of carbon from the environment:
Carbon is mostly removed as carbon dioxide from the environment in a various ways, such as
2. Addition of carbon to the environment :
Carbon comes to the environment by
Some elements like carbon, sulphur, phosphorus, etc. may exist in more than one form, having more or less different properties. For example, carbon exists as diamond, graphite, coal, coke, gas carbon, charcoal, etc.
sulphur exists in five different crystalline varieties, phosphorus as red and white phosphorus, oxygen molecules exist in oxygen gas (02 ) and ozone gas (03 ), etc. Such different forms are termed as allotropes and the element is said to exhibit the property known as allotropy.
Definition :
The property by virtue of which an element can exist In two or more forms having different physical properties but same chemical properties is called allotropy and the different forms are called allotropes.
Causes of allotropy :
The property of allotropy happens to occur due to the
All the allotropic forms of an element arc in the same physical state, i.e, if one allotrope be solid, then all other allotropes would be solid. Similarly, if one allotrope be gas, all other allotropes would be gas. Each of the allotropes bears the same basic characteristic features by which we can easily identify them as one and the same element.
The allotropes of carbon are mainly divided into two groups—
The naturally occurring crystalline allotropes of carbon are
On the other hand, the amorphous forms of carbon are of four types—
Charcoal has two different distinct forms depending on the source such as
Plant charcoal has also two different forms like
Animal charcoal is also divided into
Let us now describe the allotropes of carbon one by one:
Diamond :
It is the second hardest solid (the hardest is crystalline boron) of high density (3.51 g. cm-3) and high melting point. The crystals of a diamond is octahedral in which each carbon atom is linked to four neighbouring carbon atoms by covalent bonds (the distance, the C—C bonds are very tightly bound in its structure and that’s why diamond is so hard.
It is a colourless, transparent, lustrous substance. It has a high refractive index (2.415), due to which it produces a maximum total internal reflection of light rays incident on it, that’s why it looks so bright. When properly cut and polished, it acquires amazing lustre. One of the world-famous gems is Kohinoor of weighs 1.6 carats (1 carat = 0.200g).
Uses Of Diamond :
Graphite :
Like diamonds, graphite is also a pure form of carbon. It is a dark grey soft solid, greasy to the touch having a metallic lustre. It marks white paper black and is hence called ‘black lead’. It is lighter than a diamond.
In graphite crystals, each carbon atom is linked to three adjacent carbon atoms forming different parallel layers one over another. The length of C—C bonds in different layers is about 1.42A.
Uses Of Graphite :
Fullerenes :
In 1985, another crystalline allotropic form of carbon, other than diamond and graphite, was discovered. It contains about 60, 70 or even greater number of carbon atoms joined together.
These are called fullerenes. The smallest fullerene C-60 is the most common. The shape of it is like that of a hollow football, called a ‘bucky ball’. Fullerenes are in a stage of research. It is believed that these may find applications in electronics and medicine.
Amorphous allotropes of Carbon :
Destructive distillation of wood and others. carbonaceous matter of plant origin or animal origin in absence of oxygen results in the formation of charcoal. It is a black porous substance. Its density being very less, it can float on water.
Due to its porosity, the wood charcoal can absorb the solute of a substance and poisonous gases and also for purifying water. That is why it is used for making gas masks.
Destructive distillation of bones and animal blood brings out the products bone charcoal and blood charcoal respectively. Animal charcoal is used for purifying and producing white sugar in sugar industries, for making ivory black (paints used by artists), etc.
Sugar charcoal is the purest form of carbon and it is used as a reducing agent. Lamp black is prepared by burning rich carbonaceous substances such as kerosene oil, turpentine oil, etc. in a limited supply of air and collecting the soot on wet blankets.
It is used for making carbon papers, shoe polishes, Japanese paint, etc. And in vulcanising rubber. Coke, another form of amorphous carbon, is used in the manufacture of fuel gases. Gas carbon has a wide use for making electrodes as it is a good conductor of electricity.
Coal, the main form of amorphous carbon, is mainly used as fuel in steam engines, steam boilers, etc. On destructive distillation in absence of air, coal gives a number of products such as coal gas, coal, tar, perfumes, coke, etc.
Fuels are the substances that produce heat and light energy on burning in air or oxygen. The commonly used fuels are wood, coal, kerosene, petrol, diesel, LPG, CNG, gobar gas, etc.
These are used in various purposes such as heating, cooking, running automobiles, generating of electricity and so on. Some fuels produce more energy than others. The choice of fuel depends upon its cost, availability, and the extent of pollution it may cause.
| Solid fuels | Liquid fuels | Gaseous fuels |
| Wood, coal, charcoal, cow-dung cakes, etc. | Kerosene, petrol, diesel etc. | Petroleum gas, natural gas, biogas, LPG, CNG, etc. |
Types of fuels especially, its heating value or calorific value. The calorific value of a fuel is defined as the amount of heat produced on complete burning or combustion of unit mass of the fuel.
That is, the higher the calorific value of a fuel, the better is the fuel as it produces more heat on burning in air. Thus, an ideal fuel should have a high calorific value. Calorific value of a fuel is usually expressed in kilojoules per gram (KJ/g).
Hazardous effects on the environment due to the burning of fossil fuels :
The use of fossil fuels like petrol, diesel, coal, etc. adds many undesirable harmful substances (called pollutants) in our environment.
| Fuels | Calorific Value (KJ/g) |
| Cow dung cakes | 7 |
| Wood | 17 |
| Coal | 25-33 |
| Coke | 33 |
| Petrol | 47 |
| Kerosene | 48 |
| Diesel | 47-48 |
| LPG | 50 |
| Methane | 55 |
| Hydrogen | 150 |
These pollutants adversely affect the life of plant and animal kingdom, such as—
Energy crisis:
Most of our energy requirements are met by the burning of fossil fuels. But their stocks are very limited. So, we are to be careful to conserve fossil fuels to the extent possible. This can by done
1. Solar energy:
It is the cleanest form of energy. It causes absolutely no environmental ‘ pollution. Today scientists are able to make solar cookers, solar water heaters and many other devices which work on solar energy. Solar cells are used to generate electricity on a small scale example in watches, transistors, calculators and for domestic purposes in remote village areas.
Solar batteries are used in space flight. To obtain more electricity and more electric power, a large number of solar cells are joined together to form a solar panel. These are used in artificial satellites, space stations, water pumps, street lighting, etc.
2. Wind energy :
The energy obtained from very fast-moving wind is called wind energy. The kinetic energy of wind is converted into electrical energy by the windmills.
A windmill is used :
The advantages of wind energy are :
3. Geothermal energy :
It is the energy obtained from the heat of the core of the earth. Magma (hot molten lava) below the surface of the earth can heat nearby rocks and water as hot as 400-500°C. Some of such hot water reaches the earth’s surface as hot springs (what we see in Bakreshwar). Using a turbine, the hot water can be used to generate electricity.
4. Tidal energy :
It is the energy obtained from rising tides in coastal areas. High tide and ebb of ocean water constituting a water current can be used to rotate the turbine to produce electricity. Modern scientists are working to tidal energy on a large scale.
5. Biomass :
A mixture of waste materials and dead plants of living beings is known as biomass. Biomass concludes excreta of animals, crop residue, garbage, sewage, wood fillings and industrial wastes. Biomass can be used as a source of energy, likewise,
Advantages and disadvantages of renewable resources in comparison to Non-renewable resources :
Advantages :
Renewable resources
Disadvantages :
In comparison with non-renewable resources, the renewable resources
6. Biogas :
When the slurry of cattle-dung and water (or crop residue, sewage or other waste materials, poultry droppings, etc.) is allowed to make fermentation in absence of oxygen, they produce a mixture of methane, carbon dioxide, hydrogen and traces of hydrogen sulphide. This mixture is called biogas.
The fermentation is carried out by anaerobic bacteria which decompose the carbon compounds present in biomass into methane gas. Some of these bacteria decompose biomass to form carbon dioxide, hydrogen and other components. Finally, these combine to form methane and water.
It causes no environmental pollution. It can be used for street lighting and for running engines. The waste products such as nitrogen and phosphorus left from biogas plants are used as fertilisers.
7. Nuclear energy :
A large amount of energy is produced when the nucleus of an atom splits or when two or more nuclei of different lighter atoms combine together to form heavier nuclei. Energy stored inside heavier elements like uranium, radium, thorium, etc. is nuclear energy. This energy is used to generate electricity. It is a non-renewable energy.
Occurrence :
Carbon dioxide is present in nature both in the free state and in the combined state. It is present in the atmosphere to the extent of about 0.03% by volume. Being slightly soluble in water, it remains dissolved in natural water.
In the combined state, it occurs as minerals (carbonates and bicarbonates) such as limestone (CaC03 ), dolomite (MgC03 -CaC03 ) magnesite (MgC03 ), Calamine (ZnC03 ), etc.
Uses Of Carbon Dioxide In Chemical Industries :
It is used—
Chapter 4 Occurrence Of Carbon And Its Compounds In Nature Preparation Of Carbon Dioxide Gas :
Carbon dioxide gas can be prepared using metal carbonates and bicarbonates in two ways:
1. By the action of dilute mineral acids on metal carbonates and bicarbonates :
2. By heating metal carbonates and bicarbonates :
3. By burning carbon (for example coke, charcoal) in the air:
c + o2 → co2
Chemicals required:
Pieces of marble stone or calcium carbonate (CaC03 ) and dil. hydrochloric acid (HCl).
Apparatus required :
Woulfe bottle, thistle funnel, a delivery tube and gas jar.
Principle:
Carbon dioxide is prepared in the laboratory by the action of cold and dil. HCl on marble pieces.
Procedure :
Small pieces of marble are taken in a preparation of carbon dioxide Woulfe bottle fitted with a thistle funnel and a delivery tube. The other end of the delivery tube reaches almost to the bottom of a gas jar.
Marble pieces are covered with water. Dilute hydrochloric acid is poured into the Woulfe bottle through the thistle funnel. As the acid comes in contact with the marble, a chemical reaction takes place with the effervescence of carbon dioxide which escapes out through the delivery tube.
Sulphuric acid is not used in this method because it reacts with marble to form insoluble calcium sulphate thereby forming a layer on the marble pieces. This insoluble layer prevents the marble from coming in contact with the acid and soon the reaction ceases.
CaC03 + H2 S04 → CaS02 + C02 ↑ + H2 0
Collection:
As carbon dioxide is about 1.5 times heavier than air, it is collected by the downward displacement of air. Carbon dioxide is soluble in water, so it can not be collected by the displacement of water.
Physical Properties Of Carbon Dioxide
1. Combustibility:
It is neither combustible nor a supporter of combustion. For example, a burning wood chip when inserted into a gas jar filled with C02, it extinguishes and also the gas does not burn.
Certain active metals such as sodium, potassium and magnesium continue burning in a jar filled with C02 gas.
4Na + 3C02 → 2Na2 C03 + C
4K + 3C02 → 2 K2 C03 + C
2Mg + C02 → 2MgO + C
2. Acidic property :
Carbon dioxide is an acidic oxide, as it dissolves in water and carbonic acid (a weak acid) is formed.
co2 + H2 O→ H2 CO3
carbonic acid
3. Reaction with bases or alkalis :
Because of acidic properties, C02 reacts with alkalis like sodium hydroxide (NaOH) and sodium carbonate (Na2C03) to form salt and water.
When C02 gas is allowed to pass through clear lime water, it turns milky as insoluble calcium carbonate (salt) is formed. The milkiness however disappears on the passage of excess of C02 through it, when soluble calcium bicarbonate (salt) is formed.
4. Oxidising property:
On introducing a burning magnesium wire into a jar of C02, it burns with a dazzling light. In the reaction, Mg is oxidised to magnesium oxide and C02 is reduced to black carbon.
This reaction proves that
In the following reactions, C02 is reduced to carbon.
C02 + C →2CO
Fe + C02→ FeO + CO
Zn + C02→ZnO + CO
The greenhouse is a house made of glass walls and a glass roof, which allows the sun’s heat to go in freely but do not allow the inside heat to go out. That is, it traps the sun’s heat inside and keeps the plants inside it warm, even in winter.
Carbon dioxide and methane, the main greenhouse gases, when accumulated in the atmosphere, form a blanket above the earth. The blanket allows the infrared radiation of short wavelengths from the sun to reach the earth to warm it, but it does not allow infrared radiation of long wavelengths from the earth to escape into the space.
The retention of heat by these gases in the atmosphere is called the greenhouse effect. The increase of atmospheric temperature due to the greenhouse effect is called global warming. Global warming has introduced tremendous changes in the weather worldwide.
It has caused the melting of glaciers and polar ice caps which led to the rise in the sea level. Some scientists believe that an intensified greenhouse effect could alter the ecological balance on earth.
A polymer is a very large or giant molecule formed by the union of a very large number of smaller molecules. The term ‘polymer’ is derived from the Greek word ‘Poly’ means ‘many’ and ‘meros’ means ‘parts’. Nowadays, polymers are also known as macromolecules.
The smaller molecules which form the complex polymers are known as monomers. The formation of a polymer from single units is called polymerisation. For example, molecules of polythene, are made up of thousands of ethylene or ethene (C2H4) molecules together in the form of long chains. Hence, polythene is the ‘polymer’ and ethene is the ‘monomer’.
Polymers are of two kinds—
Natural polymers are biodegradable—as they are naturally decomposed by micro¬organisms like fungi and bacteria, whereas the synthetic polymers are non-biodegradable—as the molecules of such polymers are not decomposed by any bacteria or fungi.
Besides these, there are special type of bacteria which can produce certain biodegradable polymers, which when discarded, microbes decompose them slowly. Such polymers are used to make biodegradable plastics. There are very much eco-friendly.
Now, let us explain the properties and uses of some widely used synthetic polymers.
| Name of Polymers | Properties | Uses |
| 1. Polythene (Polymer of ethene) | Partially solid, partially flexible, whitish, translucent of moderate strength, insulator of heat* and electricity, non-reactive with chemicals. | In preparing buckets, cups, discs, water pots, carry bags, flexible containers, bottles, toys,’ packing films, table cloths, electric cables, etc. |
| 2. Teflon (Polymer of tetrafluoro ethelene) | Very tough material, resistant towards heat, a bad conductor of electricity, inactive toward acids or bases, non-sticky towards water or oil. | For making non-stick cooking utensils, gaskets, pump packings, chemical; equipment, electrical insulators, valves, seals, non-lubricated bearings, etc. |
| 3. PVC (Full name. polyvinyl chloride; polymer of vinyl chloride) | Hard horny material, thermoplastic polymer, plasticity can be increased by the addition of plasticises, inactive towards water, oil or other chemicals. | In the manufacture of raincoats, curtain clothes, gum boots, gramophone records,- slippers, artificial flooring, electrical goods, water pipes, etc. |
| 4. Thermocol | Solid but not hard, not extensible, water or oil resistant. | In making food dishes, plates; bowls, etc. |
Harmful hazards of using excessive polythene :
Due to excessive garbage of polythene, ‘ the porosity of soil is destroyed. Polythene being a non-biodegradable material, does not undergo bacterial decomposition and does not mix with the soil.
On burning, it produces pollutant gases, which cause air pollution. So, the limitless use of polythene becomes a dangerous problem to us.
The study of chemistry involves a lot of experiments which are carried out in the chemistry laboratory with the help of a number of laboratory apparatuses. Here we will describe about some simple chemical apparatus used in the chemistry laboratory which include :
Thermometer, electric cell, switch, wire, bulb, LED, chemical balance, clamp and stand, bunsen burner, spirit lamp, test tube, beaker, round bottom flask, conical flask, Woulfe bottle, gas jar; watch glass, measuring cylinder, tripod stand, wire gauze, glass rod, pipette and burette, funnel, thistle funnel, delivery tube, trough, filter paper, test tube holder, test tube rack.
Read and Learn more WBBSE Notes For Class 8 General Science And Environment
Different chemical apparatus and their uses :
Occurrence :
Oxygen is present in nature as a free element and in different compounds. Air contains about 20-6% by volume and 23% by mass, water contains 88-8% of oxygen by mass. It is the most abundant of all the elements present in the earth’s crust as oxides, nitrates, carbonates, sulphate compounds, etc.
Types Of Gas
Besides these, the plant and animal tissues contain 60-70% of oxygen by mass. During 1778, Swedish scientist Scheele, English chemist Joseph Priestly, and French scientist Lavoisier were able to prepare oxygen gas. Priestly named the gas ‘active air’ as it is very much reactive. Lavoisier gave the name ‘oxygen’, meaning ‘acid producer’.
Oxygen is used
Physical properties of oxygen :
Chemical properties of oxygen :
1. Oxygen is not combustible, but a great supporter of combustion. On introducing a glowing splint into a gas jar containing oxygen, the glowing splint rekindles inside the gas jar, but the gas does not burn itself.
2. Reaction with hydrogen :
Hydrogen burns in oxygen with a blue flame producing water vapour.
2H2 + 02 →2H20
3. Respiration :
In the living cells, food is oxidised in presence of oxygen to produce energy. The process is known as respiration.
C6H12O6 + 602 6C02 + 6H2 + heat
4. Reactivity:
Oxygen gas reacts with most of metals and non-metals to form their oxides.
Reaction with non-metals :
1. Carbon (red hot charcoal) burns in excess of oxygen to form carbon dioxide, which on reaction with water produces carbonic acid (H2C03).
C + 02→ C02
C02 H20→ H2C03 (turns moist blue litmus red)
2. Sulphur burns in oxygen with a blue flame to form sulphur dioxide, which produces sulphurous acid (H2S03) with water. It turns moist blue litmus red.
S + 02→ S02 ; S02 + H2O→ H2S03
3. Phosphorus burns in oxygen forming dense white fumes of phosphorus pentoxide (P2O5), which on dissolution with water produces phosphoric acid (H3P04).
4P + 502→ 2P205 ; P205+ BH20 →2H3P04
Common Gases Reaction With Metals
1. On heating a piece of sodium in a jar of oxygen, it bums with a golden yellow flame producing sodium oxide (Na20), which produces sodium hydroxide or caustic soda (NaOH) with water. The solution is alkaline and it turns moist red litmus blue.
4 Na + 02→ 2Na20
Na20 + H20 2NaOH (alkali)
2. Burning calcium continues burning in a jar of 02 producing a white solid calcium oxide (CaO), which being treated with water produces calcium hydroxide [Ca(OH)2]. It is an alkali.
2Ca + 02→ 2CaO ; CaO + H20→Ca(OH)2
3. Burning magnesium burns in 02 with a dazzling white flame and magnesium oxide (white powder) is produced, which on dissolution with water produces magnesium hydroxide [Mg (OH)2]; an alkali.
2Mg + 02 → 2MgO ; MgO + H20→ Mg(OH)2
4. Zinc and aluminium react with oxygen to produce zinc oxide (ZnO) and aluminium oxide (Al203) respectively. These are amphoteric oxides as they react with acids and bases separately to produce salt and water.
Absorber of Oxygen :
Preparation of oxygen gas :
1. From a dilute solution of hydrogen peroxide using Mn02 as a catalyst :
An aqueous solution of hydrogen peroxide is taken in a test tube. A little amount of Mn02 is added in the solution. A reaction takes place with the evolution of a gas. The gas is oxygen as it rekindles a glowing splinter.
Reaction :
2H202 + [MnO2] 2H20 + 02↑ + [Mn02]
In the reaction, Mn02 enhances or accelerates (i.e. catalyses) the decomposition of H202 without undergoing any change in itself and thus/Mn02 acts as a positive catalyst. The reaction takes place at ordinary room temperature.
2. From solid sodium peroxide (Na2O2) :
Chemicals required :
Sodium peroxide (Na2O2) and water.
Condition :
In the laboratory, oxygen is prepared by the action of water on Na202 at the ordinary room, temperature.
Reaction :
2Na202 + 2H20 → 2NaOH + 02↑
Procedure :
Solid sodium peroxide is taken in a conical flask filled with a dropping funnel and a bent delivery tube. The other end of the delivery tube is inserted into a vertical gas jar filled with water into a pneumatic trough.
From the dropping funnel, water is slowly dropped over solid sodium peroxide. A vigorous reaction takes place with the evolution of oxygen gas which is collected in the gas jar via a delivery tube by downward displacement of water.
3. Laboratory preparation from potassium chlorate (KCI03) :
Chemicals required :
A mixture of potassium chlorate (KCl03) and manganese dioxide (Mn02) in the ratio of 1: 4 by mass.
Condition :
On heating the mixture at a temperature of about 200-230°C, oxygen gas is prepared. In this reaction, Mn02 accelerates the decomposition of KCl03 rapidly and easily, but itself remains unchanged in mass and composition. Thus, Mn02 acts as a positive catalyst.
Reaction :
2KCl03 + [Mn02] = 2KCl + 302↑ + [Mn02] .
Procedure :
Precautions :
Occurrence :
Hydrogen gas is rarely found in free elemental state in the air (only 1 part per million). It is found in minute traces in volcanic gases and the gases evolved from petroleum mines.
The main sources of hydrogen are water, acids, alkalis, cotton, wood, oil, fat, petroleum products and other organic substances. In plant and animal tissues, it occurs as carbohydrates, proteins and vitamins.
Hydrogen gas is the lightest of all the elements in the universe. In 1756, English scientist cavendish first prepared the gas. Lavoisier named it hydrogen (in Greek, hydro = water, gen = producer) as it produces water when burnt in oxygen.
Hydrogen gas is used
Physical properties of hydrogen :
1. Combustibility :
Hydrogen gas is combustible, but not a supporter of combustion. When a lighted splinter is inserted into a gas jar filled with hydrogen, it is put off but the gas burns with a blue flame.
2. Reaction with non-metals :
Hydrogen forms non-metallic hydrides with non-metals.
Reaction with chlorine :
Equal volumes of hydrogen and chlorine react in diffused sunlight to form hydrogen chloride gas.
The reaction is negligible in the dark and explosive in direct sunlight.
Reaction with sulphur:
Hydrogen gas reacts with boiling sulphur to form hydrogen sulphide gas.
H2 + S→H2 S
Reaction with nitrogen :
Hydrogen reacts with nitrogen at 500°C and 200-1000 atmospheric pressure in presence of finely divided iron (as a catalyst) to form gaseous ammonia.
3. Reaction with metals :
Strong electro-positive metals like Na, Ca, etc. react with hydrogen when they are heated and form metallic hydrides. The metallic hydrides react with water to produce hydrogen. For example,
4. Reducing Property :
Hydrogen is a very good reducing agent. If hydrogen is passed over heated black cupric oxide (Cuo), the latter is reduced into red metallic copper (Cu) and hydrogen is oxidised into water (H2 0).
5. Occlusion :
At ordinary temperatures, large quantities of hydrogen are adsorbed by certain finely divided metals like palladium, platinum, nickel, iron, and cobalt on their surfaces. Such adsorption is called occlusion. On heating, the adsorbed gas is set free.
Adsorption is the process of accumulation of gas on the surface of a metal.
Palladium can adsorb 900 times of its own volume at ordinary temperature.
Preparation of hydrogen gas :
Laboratory preparation
chemicals required :
Impure commercial granulated zinc (Zn) and dil. sulphuric acid (H2 S04 ).
Principle :
In the laboratory, hydrogen is prepared by the reaction of zinc turnings with dil. H2 S04 at room temperature.
Reaction :
Zn + H2 S04→ ZnS04 + H2 ↑
Procedure :
Precautions :
Pure zinc reacts very slowly with dilute acids, and a thin film of H2 gas is formed on its outer surface. So, contact of Zn with acid is lost and the reaction I stop. On the other hand, in impure zinc, no such layer is formed.
The wholfe bottle and all the joints must be completely airtight since the mixture of hydrogen and air is explosive. Hydrogen gas is not collected by the downward displacement of air since the air-hydrogen mixture is highly explosive.
Conc. H2S04 is not used in the preparation of H2 gas from Zn granules. This is so because cone. H2S04 is a strong oxidising acid. It oxidises zinc into zinc sulphate (ZnS04) and itself reduces to form sulphur dioxide gas (S02). Thus, the reaction does not produce hydrogen gas.