NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline

Exercises

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

Answer:- Forest animals contribute to the forest’s growth and regeneration in the following ways.

1. They help in dispersion of plant seeds.
2. Their dung provides nutrients for plants to grow
3. Dead plants and animals are converted to humus by microorganisms.

Question:- 2. Explain how forests prevent floods.

Answer:- Forest plants prevent rainwater from falling directly on the ground, and they also store water, which aids in flood prevention.

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

Answer:- Decomposers are microorganisms that break down dead plants and animals into humus. Bacteria and fungus are two examples. They assist in nutrient recycling by digesting dead plants and animals.

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

Answer:- The photosynthetic process allows plants in the forest to consume carbon dioxide and release oxygen. This helps to keep the levels of oxygen and carbon dioxide in the atmosphere in check.

Question:- 5. Explain why there is no waste in a forest.

Answer:- In a forest, there is no waste since the waste produced is biodegradable and turned to humus by microorganisms.

Question:- 6. List five products we get from forests?

Answer:- i) Medicines

1. ii) Spices

iii) Wood

1. iv) Paper
2. v) Gum

Question:- 7. Fill in the blanks:

(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 _____________ .

Answer:- (a) The insects, butterflies, honeybees and birds help flowering plants in pollination.

(b) A forest is a purifier of water and air.

(c) Herbs form the lowest layer in the forest.

(d) The decaying leaves and animal droppings in a forest enrich the soil.

Question:- 8. Why should we worry about the conditions and issues related to forests far from us?

Answer:- We should be concerned about deforestation because it will result in flooding, a rise in global temperatures, a reduction in animal habitats, and soil erosion. Forest damage affects human habitat and environment directly or indirectly, thus it must be a cause for concern among us.

Question:- 9. Explain why there is a need of variety of animals and plants in a forest.

Answer:- All plants and animals keep the forest alive, and they also keep the C02 – 02 cycle going. Animals turn dead and decaying stuff into humus, which improves soil fertility and thus plant development. Plants and animals of various species are required in all food chains and food webs.

Question:- 10. In Fig. 17.15, 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.

Answer:-