NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline

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Updated at 2021-05-07


NCERT solutions for class 7 Science Chapter 17 Forests Our Lifeline Exercise

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

Various types of animals (herbivores, carnivores, omnivores) live in forests and contribute to the food chain.

Interconnection of the food chain will form the food web.


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.



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(1) Forests act as a natural absorber of rainwater and allow it to seep because of the roots of trees.

(2) When rainwater falls on the leaves of trees and plants, it does not fall directly on the ground.

(3) It drips slowly on the forest ground (does not stagnate) and hence prevents floods.

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(1) Decomposers are micro-organisms that convert dead plants and animals to humus.

(2) Bacteria and fungi are the two types of decomposers.

(3) They help in the process of recycling nutrients by decomposing various dead organisms such as plants and animals to form humus.

(4) Thus decomposers help in maintaining the necessary nutrient balance in the soil.

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(1) 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.

(2) Plants consume carbon dioxide released by the animals. In this way, plants help in maintaining a balance of oxygen and carbon dioxide in the atmosphere.

(3) Forests play an important role in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(1) There is no waste in a forest because waste created is bio-degradable, which gets converted to humus by the action of microorganisms.

(2) This humus ensures that the nutrients are returned back to the soil.

(3) Whatever is produced in the forest is ultimately utilized by different components of the forest.

(4) There is a food chain in every ecosystem.

(5) Forests maintain a network of food chains called the food web and hence nothing goes to waste in a forest.

Q6 : List five products we get from forests.



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

Products we get from forests are :

(1) Paper

(2) Timber and wood

(3) Turpentine, latex (rubber raw product)

(4) Spices, resin, gum

(5) Medicines and herbs

Q.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______________ .



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


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.

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

We should worry about the forest for the following reasons :

(i) A decrease in forest area would lead to an increase in carbon dioxide in the air. This will lead to an increase in the 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.

(v) Due to the reduction of forest land will turn barren which is called desertification.

(vi) Forests provide us with a large number of useful products including wood, fruits, and medicines. These products would not be available in the absence of trees and plants.

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(1) A greater variety of plants and animals in the forests helps it to regenerate and grow.

(2) A greater variety of plants means more food and habitat for the herbivores.

(3) An increase in herbivores means more food for carnivores.

(4) Decomposers help to maintain the supply of nutrients to the soil and to the growing plants.

(5) This wide variety makes a 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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(iv) Kerosene

Q.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.



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

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

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



NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline


Answer :

(iii) humus



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