Sunday, 1 May 2016

TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VII SCIENCE Chapter 17 Forests-Our lifeline




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

ANSWER:-Animals help in growing and regenerating forests in many ways. Animals work as the cleaning agents in the forest. Microorganisms work on dead bodies of plants and animals and degenerate them. Animals also help in pollination which helps in growing a number of plants. Herbivores helps the carnivores to grow as they serve as food for them. Thus flora and fauna mutually grow in the forest.

2) Explain how forests prevent floods.

ANSWER:-Forests can absorb a lot of water. The roots of the trees absorb the water and prevent it from flowing away. Roots of trees also help in percolation of water into the soil. This helps in preventing floods.

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


ANSWER:-Decomposers are micro-organisms that convert the dead plants and animals to humus. Bacteria and fungi are the two types of decomposers. They help in the process of recycling of nutrients by decomposing various dead organisms such as plants and animals to form humus.

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

ANSWER:-Plants release oxygen in the atmosphere during the process of photosynthesis. This oxygen is inhaled by the animals for respiration. During respiration, they release carbon-dioxide which is absorbed by plants. In this way the oxygen and carbon dioxide cycle goes on. Since forests contain a large number of plants, they help much in this cycle and maintain balance in nature.

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

ANSWER:-There is no waste in the forest because decomposers convert all the dead bodies of the plants and animals into the humus which gets added to the soil. Thus, no waste remains.

6) List five products we get from forests.

ANSWER :- (i) We get medicines from forests.
(ii) We get gum from forests.
(iii) We get wood which is used for many purposes like making furniture, paper etc.
(iv) We get food for animals from forests.

7) Fill in the blank:

a) The insects, butterflies, honeybees and birds help flowering plants in pollination .
(b) A forest is a purifier of air and water.
(c) Herbs form the lowest layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich the soil.

8) Why should we worry about the conditions and issues related to forests far from us?

ANSWER:-We should be worried about deforestation as it would lead to floods, increase in earth’s temperature, decreasing animals habitats and soil erosion. Damage to forests directly or indirectly affects human habitat and environment so it must be a matter of concern among us.

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


ANSWER:- A greater variety of plants and animals in the forests helps it to regenerate and grow. Greater variety of plants means more food and habitat for the herbivores. An increase in herbivores means more food for carnivores. Decomposers help to maintain the supply of nutrients to the soil and to the growing plants.

11) Which of the following is not a forest product?
(i) Gum
(ii) Plywood
(iii) Sealing wax
(iv) Kerosene

ANSWER:- Kerosene

12) Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not dependent on one another.
(iii) Forests influence the climate and water cycle.
(iv) Soil helps forests to grow and regenerate.

ANSWER:- ii) Plants and animals in a forest are not dependent on one another.

13)Micro-organisms act upon the dead plants to produce
(i) sand
(ii) mushrooms
(iii) humus
(iv) wood

ANSWER:- (iii) humus




Written By Badal Paul
The author is a passionate blogger, writer and educationalist. This blog is created to ease troubles of the Cbse students. The author holds multiple blogs and the writer of the Novel KALCHAKRA, OOM AND THE CHOSEN FIVE.