NCERT Solutions for Class 7 Science - Forests- Our Lifeline

Q1. Explain how animals dwelling in the forest help it grow and regenerate.
Ans: Animals dwelling in the forest help it grow and regenerate in the following ways:
1. Animals help in dispersing plant seeds.
2. Decaying animal dung provides nutrients for plants to grow
3. Microorganisms convert the dead plants and animals to humus

Q2. Explain how forests prevent floods.
Ans: Forest acts as a natural absorber of water. It allows rain water to seep through. In the absence of trees, the rain water would hit the ground directly resulting in flood. However, because of the presence of trees, rain water does not hit the ground directly. It rather hits the ground slowly. Hence, before flooding, all the rain water seeps through ground. In this way, forests prevent floods.

Q3. What are decomposers? Name any two of them. What do they do in the forest?
Ans: 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.

Q4. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Ans: Plants in the forests consume carbon dioxide and releases oxygen by photosynthesis process. This helps in balancing oxygen and carbon dioxide in the atmosphere.

Q5. Explain why there is no waste in a forest.
Ans: There is no waste in a forest because micro-organisms act on the wastes and convert them to humus. This humus ensures that the nutrients are returned back to the soil.

Q6. List five products we get from forests.
Ans: 
(i) Medicines
(ii) Wood
(iii) Paper
(iv) Oil
(v) Gum

Q7. Fill in the blank:
(a) The insects, butterflies, honeybees and birds help flowering plants in _______.
(b) A forest is a purifier of _______ and _______.
(c) Herbs form the _______ layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich the _______.
Ans: 
(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.

Q8. Why should we worry about the conditions and issues related to forests far from us?
Ans: There are various reasons for which we should be vigilant about matters related to forests.
(i) A decrease in forest area would lead to an increase in carbon dioxide in air. This will lead to an increase of earth’s temperature.
(ii) Soil erosion would occur if there are no forests.
(iii) Floods would be more frequent in absence of forests.
(iv) Forests provide shelter and food to animals. When forests are adversely affected, the habitats of wild animals are also adversely affected.
Therefore, we need to conserve our forests.

Q9. Explain why there is a need of variety of animals and plants in a forest.
Ans: Variety of plants and animals in the forests helps plants to regenerate and grow. More excellent range of plants supports herbivores, which in turn serve as food for carnivores. Decomposers turn dead animals and plants into humus. Thereby maintaining the nutrient recycling. This wide variety makes forest a dynamic living entity.

Q10. In figure, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:

Clouds, Rain, Atmosphere, Carbon dioxide, Oxygen, Plants, Animals, Soil, Roots, Water table.
Ans:

Q11. Which of the following is not a forest product?
(i) Gum
(ii) Plywood
(iii) Sealing wax
(iv) Kerosene
Ans: (iv) Kerosene

Q12. 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.
Ans: (ii) Plants and animals in a forest are not dependent on one another.

Q13. Micro-organisms act upon the dead plants to produce
(i) sand
(ii) mushrooms
(iii) humus
(iv) wood
Ans: (iii) humus