Friday, November 16, 2012

CBSE 7th Grade Chapter 17- Forest – Our Life Line

Answer these question

1. Question:  Explain how animals dwelling in the forest help it grow and regenerate.

Ans: Animals in the forest help it grow and regenerate in many ways like: Animals help in dispersal of sees. Micro organism supply nutrients for growth.  Many seedlings growing in a decaying heap on animal droppings.

2. Explain how forests prevent floods.

Ans: Forest absorb rainwater and allows it to seep naturally.its leaves and branches prevent rain to hit the ground directly.

3. What are decomposers? Name any two of them. What do they do in the forest?

Ans: The micro-organisms which convert the dead plants and animals to humus are known as decomposers like Fungi and bacteria. They  convert dead leaves and dead animals  into humus

4. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

Ans: During respiration plants and animals take in oxygen  and release carbon dioxde. During  photosynthesis plants take in carbon dioxide and release oxygen. So plants help to maintain the oxygen and carbon dioxide balance in the atmosphere. This is why forests are called green lungs.

5. Explain why there is no waste in a forest.

There are several organisms and micro-organisms that live in the soil convert waste into usefull nutrients called humus. This is why there is no waste in forest.

6. List five products we get from forests?

Ans: We get several useful products from forests like wood, spices, gum, oils, honey, sealing wax, catechu, fodder for animals, medicinal plants etc.

7. What are the importances of forests?

Ans: Forests provide us with oxygen. They protect soil and provide habitat to a large number of animals. Forests help in bringing good rainfall in neighboring areas. They are a source of medicinal plants, timber and many other useful products.

8. What would happen if forests disappear?
or,
Why should we worry about the conditions and issues related to forests far from us?

Ans: the conditions and issues we have to face when  forests disappears are
 (a)Soil erosion: Trees in a forest hold soil with their roots. If trees are gone, soil will be washed away.
(b) Land slides: Without trees, land will be very unstable and easily down the slope
(c) Water pollution: Without tree roots holding the soil  in a forest, soil will run into the river.
(d) Temperature increase
(e) Loss of biodiversity: Plants and animals will lose their food and shelter
(f) Floods: Bald hills and mountains can no longer hold back sudden flows of water, which cause
floods.
(g) Increase in carbon dioxide: Depletion of forests results in increase in carbon dioxide, which will cause global warming.

9. Explain why there is a need of variety of animals and plants in a forest?

Ans: Animals and plants in a forest are dependent on the other for food. So there is a need of variety of animals and plants in a forest. Many food chains can be found in the forest like Grass→ insects→ frog→ snake→ eagle.

10.Fill in the blank:

(a) The insects, butterflies, honeybees and birds help flowering plants in ------.
Pollination
(b) A forest is a purifier of ------------  and -----------------.
Air, Water
(c) Herbs form the ----------------- layer in the forest.
lowest
(d) The decaying leaves and animal droppings in a forest enrich -----------.
Soil(Fertility the Soil)

Continue learning : Chapter-17-Forest –Our Life Line  

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