NCERT Solutions Class 7 Science
The NCERT Solutions in English Language for Class 7 Science Chapter – 17 (Forests: Our Lifeline) has been provided here to help the students in solving the questions from this exercise.
Chapter – 17 (Forests: Our Lifeline)
1. Explain how animals dwelling in the forest help it grow and regenerate.
Answer – Animals which live in the forest help it grow and regenerate in following ways:
- By eating vegetation they clear land for fresh growth
- Animals help flowering plants in pollination and seed dispersal
- Dead remains of animals make humus after decomposition. This increases soil fertility
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 – Forests are called the green lungs. This is because plants in forests release oxygen through the process of photosynthesis and help in providing oxygen to animals for respiration. Plants consume carbon dioxide released by the animals. In this way, plants help in maintaining a balance of oxygen and carbon dioxide in atmosphere.
5. Explain why there is no waste in a forest.
Answer – 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.
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.
(v) We get sealing wax from forests.
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 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 worry about the forest for the following reasons.
- A decrease in forest results in an increase in carbon dioxide content in the atmosphere. This results in global warming.
- Depletion of forests results in soil erosion
- Decrease in forest adversely affect the lives of animals living in the forest.
- Absence of forests leads to flooding more often.
- Due to the reduction of forest land will turn barren which is called desertification.
9. Explain why there is a need of variety of animals and plants in a forest.
Answer – 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 maintain nutrient recycling. This wide variety makes forest a dynamic living entity.
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 –
11. Which of the following is not a forest product?
(i) Gum
(ii) Plywood
(iii) Sealing wax
(iv) Kerosene
Answer – (iv) 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 – is incorrect
13. Micro-organisms act upon the dead plants to produce
(i) sand
(ii) mushrooms
(iii) humus
(iv) wood
Answer – (iii) humus
