Forests: Our Lifeline – Class 7 Science Notes and Questions Answers

Introduction: Forests are one of the most important natural resources on our planet. They act as the lifeline of living beings by providing oxygen, food, shelter, raw materials, and regulating the Earth’s climate. The NCERT Class 7 Science Chapter “Forests: Our Lifeline” explains how forests support biodiversity, maintain balance in the ecosystem, and are essential for human survival. This article includes easy notes, important questions, and NCERT-based solutions for exam preparation, explained in simple language.

📘 Class 7 Science Chapter – Forests: Our Lifeline Notes

1. Forest as an ecosystem: A forest is a large area covered with different types of trees, plants, animals, and microorganisms. All these organisms interact with each other and their physical surroundings to form an ecosystem.

2. Components of a forest: Forests have biotic (living) and abiotic (non-living) components.

  • Biotic: Plants, trees, shrubs, animals, birds, insects, microorganisms.
  • Abiotic: Soil, water, air, sunlight, temperature, rocks.

3. Layers of the forest:

  • Canopy: The uppermost branches and leaves of tall trees form a roof-like structure.
  • Understorey: The layer beneath the canopy, containing shrubs and small plants.
  • Forest floor: The lowest layer where herbs, grasses, decomposers, and animals live.

4. Role of animals: Animals like herbivores, carnivores, and omnivores maintain the food chain. Insects, birds, and reptiles play roles in pollination, seed dispersal, and controlling pests.

5. Decomposers: Fungi, bacteria, and insects break down dead plants and animals into nutrients, which return to the soil, making it fertile.

6. Forest as carbon sink: Forests absorb carbon dioxide during photosynthesis and release oxygen, balancing the gases in the atmosphere. That is why they are called the “green lungs” of the Earth.

7. Water cycle in forests: Trees absorb water from the soil and release water vapor through transpiration. This maintains humidity and brings rainfall, supporting agriculture and life.

8. Interdependence in forests: Every organism in the forest depends on the other – plants provide food and shelter, animals help in pollination and seed dispersal, and decomposers recycle nutrients.

9. Importance of forests:

  • Prevent soil erosion and floods.
  • Maintain oxygen-carbon dioxide balance.
  • Provide timber, medicines, fruits, and fuelwood.
  • Maintain biodiversity and climate stability.

10. Deforestation effects: Cutting down forests leads to imbalance in nature, soil erosion, loss of rainfall, global warming, and extinction of species.

Summary: Forests are essential for the survival of life. Protecting forests ensures environmental stability, sustainable living, and a secure future.

📝 Class 7 Science – Forests: Our Lifeline Questions and Answers

👉 Multiple Choice Questions (7)

  1. Which of the following is called the “lungs of the Earth”?
    a) Ocean
    b) Forest
    c) Desert
    d) Grassland
    Answer: b) Forest
  2. Which of the following is a decomposer?
    a) Cow
    b) Bacteria
    c) Lion
    d) Deer
    Answer: b) Bacteria
  3. The uppermost layer of the forest is called:
    a) Shrub layer
    b) Canopy
    c) Forest floor
    d) Understorey
    Answer: b) Canopy
  4. Trees release oxygen during:
    a) Respiration
    b) Photosynthesis
    c) Transpiration
    d) Fermentation
    Answer: b) Photosynthesis
  5. Forests help in maintaining:
    a) Only soil fertility
    b) Only water cycle
    c) Oxygen and carbon dioxide balance
    d) None of these
    Answer: c) Oxygen and carbon dioxide balance
  6. Which of the following prevents soil erosion?
    a) Rocks
    b) Animals
    c) Trees
    d) Rain
    Answer: c) Trees
  7. The community of living organisms interacting with non-living components is called:
    a) Habitat
    b) Ecosystem
    c) Population
    d) Environment
    Answer: b) Ecosystem

👉 Very Short Answer Questions (7)

  1. What is an ecosystem?
    Answer: An ecosystem is a system where living organisms interact with each other and with the non-living environment.
  2. What is the canopy?
    3. Answer: The canopy is the roof-like layer formed by the branches and leaves of tall trees.
  3. Name two decomposers in the forest.
    4. Answer: Fungi and bacteria.
  4. Why are forests called carbon sinks?
    5. Answer: Because they absorb carbon dioxide and release oxygen.
  5. Name two forest products used daily.
    6. Answer: Timber and medicinal plants.
  6. What prevents soil erosion in forests?
    7. Answer: Tree roots bind the soil, preventing erosion.
  7. Name two herbivores found in forests.
    8. Answer: Deer and elephants.

👉 Short Answer Questions (7)

  1. Explain the role of decomposers in a forest.
    Answer: Decomposers such as fungi and bacteria break down dead plants and animals into nutrients, enriching the soil and maintaining the cycle of life in the forest.
  2. How do forests help in rainfall?
    3. Answer: Through transpiration, trees release water vapor into the atmosphere, increasing humidity and helping in cloud formation, which leads to rainfall.
  3. What is interdependence in a forest?
    4. Answer: In forests, plants, animals, and decomposers depend on each other. Plants provide food, animals help in pollination and seed dispersal, while decomposers recycle nutrients back into the soil.
  4. Why is the forest floor dark and damp?
    5. Answer: Because the canopy and understorey block sunlight, making the forest floor shaded, cool, and moist.
  5. What happens if forests disappear?
    6. Answer: Disappearance of forests would lead to soil erosion, loss of biodiversity, imbalance in gases, less rainfall, and climate change.
  6. Give any three uses of forests.
    7. Answer: Forests provide timber, maintain oxygen balance, and protect soil from erosion.
  7. Why are forests called lifelines?
    8. Answer: Because they support life by providing oxygen, food, water, raw materials, and maintaining ecological balance.

👉 Long Answer Questions (7)

  1. Explain the structure of a forest with its layers.
    Answer: A forest has three main layers: the canopy (upper layer formed by tall trees), the understorey (middle layer with shrubs and small trees), and the forest floor (lower layer with herbs, grasses, and decomposers). Each layer plays a vital role in supporting biodiversity and ecological balance.
  2. Describe the importance of forests in the water cycle.
    3. Answer: Forests play a key role in the water cycle. Trees absorb water from soil and release it as water vapor during transpiration. This maintains atmospheric moisture, leads to cloud formation, and brings rainfall. Without forests, rainfall would decrease and droughts would increase.
  3. How do forests maintain the balance of oxygen and carbon dioxide?
    4. Answer: During photosynthesis, plants absorb carbon dioxide and release oxygen. Forests, with millions of trees, act as carbon sinks and green lungs, maintaining the balance of gases in the atmosphere.
  4. What role do animals play in forests?
    5. Answer: Animals maintain food chains, control population of species, help in pollination, and disperse seeds. Herbivores feed on plants, carnivores regulate herbivore numbers, and omnivores help in balancing both. Together, they maintain ecological balance.
  5. Explain how forests prevent soil erosion and floods.
    6. Answer: Roots of trees bind soil, preventing erosion by wind and water. Forest cover also slows the flow of rainwater, allowing it to seep into the soil, thereby preventing floods.
  6. What are the harmful effects of deforestation?
    7. Answer: Deforestation leads to soil erosion, loss of fertility, floods, droughts, global warming, and extinction of species. It disturbs the natural cycles and reduces the availability of forest products.
  7. Why should we conserve forests? Suggest some measures.
    8. Answer: We should conserve forests because they are essential for life, climate stability, and biodiversity. Measures include afforestation, controlled use of timber, preventing illegal cutting, community awareness, and sustainable forest management.

Related Reading: More Class 7 Science Q&A