Class 10 Science Chapter 13 Our Environment

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Class 10 → Science → Chapter 13: Our Environment

I. Chapter Summary:

This chapter focuses on the interaction between living organisms and their environment. It explains ecosystems, food chains, food webs, and the flow of energy in nature. Students learn about environmental problems such as pollution and waste accumulation, especially the harmful effects of non-biodegradable substances like plastics. The chapter also highlights the importance of sustainable development and proper waste management to protect our environment for future generations.

II. Key Concepts Covered:

  1. Environment:
    Everything that surrounds us, including living (biotic) and non-living (abiotic) components.
  2. Ecosystem:
    A system formed by interaction between living organisms and their environment.
  3. Biotic and Abiotic Components:
    • Biotic: Plants, animals, microorganisms
    • Abiotic: Air, water, soil, temperature
  4. Food Chain:
    Sequence of organisms where each is eaten by the next.
  5. Trophic Levels:
    Different levels in a food chain (producers, consumers, decomposers).
  6. Food Web:
    Network of interconnected food chains.
  7. Energy Flow in Ecosystem:
    Energy flows from sun → producers → consumers.
  8. 10% Law:
    Only 10% of energy is transferred to the next trophic level.
  9. Biodegradable and Non-Biodegradable Substances:
    • Biodegradable: Can be decomposed (e.g., food waste)
    • Non-biodegradable: Cannot be decomposed (e.g., plastic)
  10. Environmental Problems:
    Pollution, waste accumulation, ecosystem imbalance.

III. Important Questions:

(A) MCQs (1 Mark)

  1. The organisms that make their own food are called:
    (a) Consumers
    (b) Decomposers
    (c) Producers ✅
    (d) Carnivores
  2. The 10% law is related to:
    (a) Water cycle
    (b) Energy transfer in food chain ✅
    (c) Photosynthesis
    (d) Respiration
  3. Which is a non-biodegradable substance?
    (a) Paper
    (b) Vegetable waste
    (c) Plastic ✅
    (d) Cotton
  4. Food web is:
    (a) Single food chain
    (b) Network of food chains ✅
    (c) Only producers
    (d) Only consumers

(B) Short Answer Questions (2/3 Marks)

  1. Define ecosystem with an example.
  2. What is a food chain? Give one example. (CBSE PYQ 2020)
  3. Differentiate between biodegradable and non-biodegradable substances.
  4. What are trophic levels?

(C) Long Answer Questions (5 Marks)

  1. Explain energy flow in an ecosystem with diagram. (CBSE PYQ 2019)
  2. Describe food chain and food web with examples.
  3. Explain harmful effects of non-biodegradable substances. (CBSE PYQ 2020)
  4. Explain role of decomposers in environment.

(D) HOTS Questions

  1. Why are food chains usually short?
  2. What will happen if decomposers are removed from ecosystem?

IV. Key Formulas/Concepts:

  • 10% Law: Only 10% of energy passes to next trophic level
  • Energy Flow: Sun → Producers → Consumers → Decomposers

Example:
Grass → Deer → Tiger

V. Deleted Portions (CBSE 2025–2026):

  • Detailed study of ozone layer depletion (partially reduced)
  • Some detailed case studies on environmental issues

(Refer to NCERT official website for latest updates)

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026):

Unit/Chapter Estimated Marks Type of Questions Typically Asked
Our Environment 5–7 Marks MCQs, Case-based, Short & Long Answer

Note: This is an estimate; actual marks may vary.

VII. Previous Year Questions (PYQs):

1 Mark

  • What is food chain? (2018)

2/3 Marks

  • Define ecosystem. (2019)
  • What are decomposers? (2020)

5 Marks

  • Explain energy flow in ecosystem. (2019)
  • Effects of non-biodegradable substances. (2020)

VIII. Real-World Application Examples:

  • Waste segregation: Dry and wet waste
  • Recycling: Paper, plastic reuse
  • Food chains: Farm ecosystem
  • Environmental protection: Tree plantation

IX. Student Tips & Strategies for Success:

Time Management:

  • Revise diagrams and flow charts
  • Practice definitions daily

Exam Preparation:

  • Learn examples of food chains
  • Focus on 10% law

Stress Management:

  • Study with diagrams
  • Use mind maps

X. Career Guidance & Exploration:

After Class 10:

Science Stream:

  • Environmental Science
  • Ecology, Forestry

Commerce Stream:

  • Environmental Economics

Arts Stream:

  • Geography, Sustainability Studies

XI. Important Notes:

  • Diagrams (food chain/web) are important
  • Use real-life examples in answers
  • Focus on concept clarity
  • Refer NCERT regularly
  • Practice PYQs for better preparation

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