NCERT Solutions for Class 8th: Ch 7 Conservation of Plants and Animals Science
Page No: 86Excercise
1. Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called a __ .
(b) Species found only in a particular area are known as ______.
(c) Migratory birds fly to far away places because of _____ changes.
Answer
(a) A place where animals are protected in their natural habitat is called a sanctuary.
(b) Species found only in a particular area are known as endemic.
(c) Migratory birds fly to far away places because of climatic changes.
2. Differentiate between the following.
(a) Wildlife sanctuary and biosphere reserve
Wildlife sanctuary | Biosphere reserve |
| It is an area within which animals are protected from possible dangers such as hunting. Their habitat is also conserved in this area. | It is a large protected area constructed for the conservation of biodiversity. |
| It provides protection and suitable living conditions to wild animals. | It helps in the conservation of various life forms such as plants, animals, and micro-organisms. |
(b) Zoo and wildlife sanctuary
Zoo | Wild life sanctuary |
| Zoos are smaller places having some animals protected for the public view. | Wildlife Sanctuary are larger places having wild animals in their natural habitat |
| It is an artificial habitat. | It conserves the natural habitat of animals. |
| It provides protection only. | It provides protection and suitable living condition to wild animals. |
(c) Endangered and extinct species
Endangered species | Extinct species |
| It is a population of species that is on the verge of becoming extinct. | It is a population of species that no longer exists. Hence, it is extinct. |
| Blue whale, tiger, leopard, etc. are examples of endangered species. | Dodo, passenger pigeon, etc. are examples of extinct species. |
(d) Flora and fauna
Flora | Fauna |
| It refers to all living plants in a particular area. | It refers to all animals living in a particular area. |
| Sal, teak, mango, etc. form the flora of Pachmarhi biosphere reserve. | Leopard, wolf, wild dog, etc. form the fauna of Pachmarhi biosphere reserve. |
3. Discuss the effects of deforestation on the following.
(a) Wild animals: When forests are cut, the natural habitat of the animals is destroyed. Without the natural habitat the animals are left with no place to live and breed. As a result of this many animals are at the verge of extinction.
(b) Environment: Environment is adversely affected by deforestation as ecological balance is disturbed. Carbon dioxide is not absorbed by plants and it gets accumulated in the atmosphere to cause global warming which increases the temprature of earth and disturb water cycle.
(c) Villages (Ruaral Areas): Deforestation leads to soil erosion and results in flash floods. This hampers agricultural activities and thus disturbs the people in rural areas.
(d) Cities (Urban Areas): Deforestation in cities can increase the risk of many natural calamities such as floods and droughts in that area.
(e) Earth: The whole earth is full of various ecosystems which together make the biosphere. Deforestation disturbs the balance in the biosphere. It disturbs climatic patterns.
(f) The next generation: They will not be able to see wide variety of flora and fauna also not get clean and cool environment. They will have to breathe poisonous gas. Life would be very difficult for the next generation.
4. What will happen if:
(a) we go on cutting trees.
(b) the habitat of an animal is disturbed.
(c) the top layer of soil is exposed.
Answer
(a) If we go on cutting trees then:
→ Earth will loose its top fertile soil layer and get conevrted into desert.
→ The ecological balance will get disturbed and and floods and drought will become more frequent.
→ Wildlife will also be affected.
(b) The habitat of an animal provides it with necessities such as shelter, food, and protection. If the habitat of an animal is disturbed, then it will be forced to go to other places in search of food and shelter. The animal could get killed by other animals in this process.
(c) If the top layer of soil is exposed, then it will gradually expose the lower layer of soil, which is hard and rocky in nature. This type of soil is less fertile as it contains less humus. Continued soil erosion will make the land barren or infertile.
5. Answer in brief:
(a) Why should we conserve biodiversity?
Answer
We should conserve biodiversity because it is very important for all living organisms and for the environment. We should conserve biodiversity to save it from becoming extinct.
(b) Protected forests are also not completely safe for wild animals. Why?
(e) What is Red Data Book?
(b) Protected forests are also not completely safe for wild animals. Why?
Answer
Protected forests are not completely safe for wild animals because people who live near or adjacent to forests use resources from forests to fulfil their own requirements. In this process, wild animals are killed and sold for lucrative amounts of money.
(c) Some tribals depend on the jungle. How?
(c) Some tribals depend on the jungle. How?
Answer
Tribals gather food, fodder, and fallen branches of trees from forests. Hence, they depend on forests for their daily requirements.
(d) What are the causes and consequences of deforestation?
(d) What are the causes and consequences of deforestation?
Answer
The main cause of deforestation is growing urbanization and industrialization. Need for more land and resources have lead to the cutting down of forests.
Consequences of deforestation are as follows:
→ Soil erosion
→ Depletion of groundwater
→ Flash flood
→ Global warming
Consequences of deforestation are as follows:
→ Soil erosion
→ Depletion of groundwater
→ Flash flood
→ Global warming
(e) What is Red Data Book?
Answer
Red Data Book is a source book that maintains an international list of all endangered animal and plant species.
(f) What do you understand by the term migration?
(f) What do you understand by the term migration?
Answer
Migration refers to the movement of an organism or a group of organisms from its natural habitat to another place at a particular time every year.
6. In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.
Answer
No. It is not at all justified to cut trees to meet the ever increasing demands of human population. Forests are the habitat of several organisms including wild animals. They provide us with good quality air as they give out O2 and absorb the harmful CO2 gas from the atmosphere. In the process, they prevent the excessive heating of the atmosphere. They prevent soil erosion and natural calamities such as floods and droughts. They increase the fertility of the soil and help conserve biodiversity. The cutting of forests to meet the demands of growing human population will lead to global warming, soil erosion, greenhouse effect, droughts, floods, and many more problems. The destruction of forests will disturb the balance of nature. Hence, forests must be conserved.
Answer
We can contribute to the maintenance of green wealth by taking following actions:
→ We can grow new plants in our locality.
→ Water them regularly and care of them.
→ The existing plants should be properly nourished.
→ Encouraging awareness among the people in the locality about the importance of growing trees.
8. Explain how deforestation leads to reduced rainfall.
Answer
Plants absorb water from the soil and evaporates it to form clouds. Deforestation leads to cutting down of trees. As a result less water is absorbed from the soil and it disturbs the water cycle. The formation of clouds become difficult which leads to reduced rainfall.
10. Why should paper be saved? Prepare a list of ways by which you can save paper.
Answer
Paper should be saved because it takes around seventeen full grown trees to make one tonne of paper. Trees, as we know, are important to maintain a balance of nature. Therefore, in order to save trees and prevent the impact of their loss on living organisms, we need to save paper.
Ways by which paper can be saved:
→ Collect used paper and recycle it.
→ Use both sides of a paper for writing.
→ Spread awareness about the importance of paper.
→ Use paper intelligently.
11. Complete the world puzzle.
Down
1. Species on the verge of extinction.
2. A book carrying information about endangered species.
5. Consequence of deforestation.
Across
1. Species which have vanished.
3. Species found only in a particular habitat.
4. Variety of plants, animals and microorganisms found in an area.
Answer
1. ENDANGERED
2. RED DATA BOOK
5. DESERTS
Across
1. EXTINCT
3. ENDEMIC
4. BIODIVERSITY
