CBSE Class 7 Science Chapter 17: Forests: Our Lifeline - NCERT Solutions

Reviewed by · Updated on

NCERT Solutions PDF Class 7 PDF

This chapter, Forests: Our Lifeline, delves into the critical role forests play in our ecosystem. The NCERT Solutions for Class 7 Science, Chapter 17, explain the intricate relationships within a forest, highlighting how animals contribute to its growth and regeneration through seed dispersal and nutrient cycling. It details the function of forests as natural flood preventers by absorbing rainwater and the vital role of decomposers like fungi and bacteria in breaking down organic matter into nutrient-rich humus. The solutions also emphasize how forests maintain the atmospheric balance of oxygen and carbon dioxide through photosynthesis and respiration, functioning as a self-sustaining system with no waste. Furthermore, students will learn about the various products derived from forests, such as timber, medicines, and food items. These solutions provide clear, step-by-step explanations to help students understand complex ecological concepts and prepare effectively for their exams.

Home

Quick info

BoardCBSE
ClassClass 7
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 17: Forests: Our Lifeline

Chapter summary

Chapter 17, Forests: Our Lifeline, focuses on understanding the structure and function of forest ecosystems. The NCERT Solutions cover the interdependence of living organisms within a forest, the processes of seed dispersal, decomposition, and nutrient cycling. It explains the role of forests in environmental regulation, such as preventing floods and maintaining atmospheric gas balance. The solutions also list essential forest products and reinforce learning through fill-in-the-blanks exercises, aiding students in grasping the significance of forests.

Learning outcomes

  • Understand the role of animals in forest growth and regeneration.
  • Explain how forests prevent floods.
  • Identify decomposers and their function in a forest ecosystem.
  • Describe the process of maintaining the oxygen-carbon dioxide balance by forests.
  • Recognize forests as natural recycling systems.
  • List various products obtained from forests.

Topics covered

Paper topics

  • Role of animals in forests
  • Seed dispersal
  • Forests and flood prevention
  • Decomposers (fungi, bacteria)
  • Humus formation
  • Nutrient cycling in forests
  • Oxygen-carbon dioxide balance
  • Photosynthesis and respiration
  • Forests as recycling systems
  • Forest products
  • Forest layers (herbs)
  • Interdependence in forest ecosystems

Important topics

  • Role of forests in environmental balance (oxygen-CO2, flood prevention)
  • Function of decomposers and nutrient cycling
  • Interdependence of organisms in a forest ecosystem
  • Importance of animals in seed dispersal and regeneration
  • Products derived from forests

PDF preview

Read page by page below. PDF is streamed from the official NCERT website — no download button on this page.

Loading document …
Page of
Loading page …

Questions and Solutions

Question 1

Explain how animals dwelling in the forest help it grow and regenerate.
Solution: Animals play a crucial role in the growth and regeneration of forests through several mechanisms. Firstly, they aid in the dispersal of seeds; when animals eat fruits, they excrete the seeds in different locations, helping new plants to grow far from the parent tree. Secondly, the excreta of animals and their dead bodies, upon decomposition, enrich the soil. Microorganisms break down this organic matter into humus, which is a nutrient-rich substance that acts as manure for plants, promoting their growth. This continuous cycle ensures the forest ecosystem remains healthy and vibrant.

Question 2

Explain how forests prevent floods.
Solution: Forests act as natural regulators of water flow, significantly helping to prevent floods. The dense canopy of trees intercepts rainwater, reducing the direct impact on the ground. This allows the water to drip slowly onto the forest floor. Furthermore, the roots of trees and the porous soil structure in forests absorb a large amount of rainwater, allowing it to seep into the ground. This process slows down the rate at which water reaches rivers and streams, preventing them from overflowing and causing floods.

Question 3

What are decomposers? Name any two of them. What do they do in the forest?
Solution: Decomposers are microorganisms, such as fungi and bacteria, that play a vital role in breaking down dead and decaying organic matter from plants and animals. In a forest, decomposers convert dead leaves, fallen branches, and animal remains into humus. This humus mixes with the soil, enriching it with essential nutrients like nitrogen, phosphorus, and potassium. By recycling these nutrients, decomposers help maintain the fertility of the forest soil, supporting the growth of new plants and ensuring the continuation of the ecosystem.

Question 4

Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Solution: Forests are essential for maintaining the balance of oxygen and carbon dioxide in the atmosphere. Plants in the forest perform photosynthesis, a process where they absorb carbon dioxide from the atmosphere and release oxygen. Simultaneously, all living organisms, including plants and animals, respire. Respiration consumes oxygen and releases carbon dioxide. Forests, with their vast number of plants, absorb large quantities of carbon dioxide for photosynthesis and release a significant amount of oxygen. This continuous exchange helps regulate the atmospheric levels of these gases, preventing an excessive buildup of carbon dioxide and ensuring a sufficient supply of oxygen for life.

Question 5

Explain why there is no waste in a forest.
Solution: A forest functions as a highly efficient, natural recycling system, which is why there is essentially no waste. All the organic matter that is produced—whether from dead plants, fallen leaves, or deceased animals—is broken down by decomposers (like fungi and bacteria) into simpler substances. These substances, primarily humus, are then returned to the soil, providing nutrients that are utilized by living plants for their growth. This continuous cycle ensures that all components are reused and nothing is truly wasted, creating a self-sustaining ecosystem.

Question 6

List five products we get from forests?
Solution: Forests provide us with a wide variety of essential products. Five important products include:
  1. Timber and wood (used for furniture, construction, paper)
  2. Fruits and vegetables (wild edible plants)
  3. Medicines and herbs (many medicinal plants grow in forests)
  4. Resins and gums (used in various industries)
  5. Latex (raw product for rubber)

Question 7

Fill in the blank:
  1. The insects, butterflies, honeybees and birds help flowering plants in ______.
  2. A forest is a purifier of _____ and _____.
  3. Herbs form the _____ layer in the forest.
  4. The decaying leaves and animal droppings in a forest enrich the ______.
Solution:
  1. The insects, butterflies, honeybees and birds help flowering plants in pollination.
  2. A forest is a purifier of air and water.
  3. Herbs form the lowest layer in the forest.
  4. The decaying leaves and animal droppings in a forest enrich the soil.

Common mistakes

  • Confusing the roles of different organisms in the forest ecosystem.
  • Not fully understanding the process of seed dispersal by animals.
  • Underestimating the importance of decomposers in nutrient cycling.
  • Failing to connect forest functions to environmental benefits like flood prevention.

Revision tips

  • Draw a diagram of a forest ecosystem showing different layers and organisms.
  • Focus on understanding the 'why' behind each function, like why forests prevent floods.
  • Memorize the list of forest products and the roles of decomposers.
  • Practice the fill-in-the-blanks questions to reinforce key terms and concepts.

Practice MCQs

Q1. Which of the following is a primary role of animals in forest regeneration?

Q2. How do forests help in preventing floods?

Q3. What are decomposers and what is their main function in a forest?

Q4. The process by which plants take in carbon dioxide and release oxygen is called:

Q5. Which of these is NOT a product typically obtained from forests?

Frequently asked questions

How do animals help forests grow and regenerate?

Animals aid in forest growth by dispersing seeds to new areas and by their excreta and decomposed bodies enriching the soil with nutrients, acting as manure.

What is the role of decomposers in a forest?

Decomposers, like fungi and bacteria, break down dead plants and animals into humus, which is rich in nutrients and essential for plant growth, thus recycling matter in the forest.

How do forests prevent floods?

Forests act as natural absorbers of rainwater. The canopy slows down rainfall, and the soil allows water to seep in gradually, reducing surface runoff and preventing floods.

Why are forests considered 'recycling factories'?

Forests are recycling factories because all the organic matter produced (plants, animals) is eventually broken down by decomposers and reused by plants, creating a continuous cycle with no waste.

What is the importance of the oxygen-carbon dioxide balance maintained by forests?

Forests maintain this balance through photosynthesis (taking in CO2, releasing O2) and respiration (taking in O2, releasing CO2), which is crucial for life on Earth.

Can you list some essential products we get from forests?

Yes, forests provide essential products such as timber, fruits, vegetables, spices, gum, latex (for rubber), medicines, and herbs.

Important links

Content reviewed by the NCERT Help team. Editorial Team and update policy

NCERT Solutions PDF PDF on NCERT Help. URL unchanged for search indexing.