NCERT Class VII Science Solutions: Chapter 17-Forests: Our Lifeline Part 2

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Question 3:

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

Answer:

The micro-organisms which convert the dead plants and animals to humus are known as decomposers.

Examples: Fungi and Bacteria.

Decomposers recycle and convert the dead matter into humus which mixes with forest soil and provide necessary nutrients to plants. Thus decomposers help in maintaining the necessary nutrient balance in the soil.

This image shows examples of decomposers

Examples of Decomposers

Question 4:

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

Answer:

Forests play an important role in maintaining the balance between oxygen and carbon dioxide in the atmosphere. Forest works like a self-sustaining system. Whatever is produced in the forest is utilized by different components of the forest. Animals during respiration take in oxygen and release carbon dioxide. Plants take in carbon dioxide and release oxygen through the process of photosynthesis. Even the waste is converted into beneficial substances in a forest. Due to this, there is no waste in a forest.

This diagram shows oxygen and carbon dioxide in the atmosphe …

Oxygen and Carbon Dioxide in the Atmosphere

Question 5:

Explain why there is no waste in a forest.

Answer:

Forests are excellent, perfect and natural recycling factories. All animals, whether herbivores or carnivores, depend ultimately on plants for food. Herbivores eat plants and their products. Carnivores eat herbivores. Dead remains of animals and plants are decomposed by micro-organisms into humus. Whatever is produced in the forest is ultimately utilized by different components of the forest. Forests maintain a network of food chains called food web and hence nothing goes waste in a forest.