Here are easy & exam-ready notes + topic-wise previous year questions for
📗 Chapter: Our Environment — Class 10 (CBSE, NCERT)
✅ Prepared as per NCERT & CBSE board pattern
🌏 Notes:
Our Environment
🔷 1. What is Environment?
- Environment: The sum of all external conditions that affect living organisms.
- Includes biotic (living) and abiotic (non-living) components.
🔷 2. Ecosystem
- Ecosystem = Interaction between biotic & abiotic factors in a given area.
- Components:
- Biotic: Plants, animals, microorganisms
- Abiotic: Sunlight, water, air, soil
- Examples: Pond, forest, desert.
🔷 3. Food Chains & Food Web
- Food Chain: Linear sequence of who eats whom.
- Example: Grass → Grasshopper → Frog → Snake → Hawk
- Food Web: Interconnected food chains in an ecosystem.
🔷 4. Trophic Levels
- Steps in a food chain.
- Level 1: Producers (plants)
- Level 2: Herbivores (primary consumers)
- Level 3: Carnivores (secondary & tertiary consumers)
- Decomposers: Break down dead matter (bacteria, fungi).
🔷 5. Energy Flow
- Energy flows in one direction only — from Sun → Producers → Consumers → Decomposers.
- Only ~10% energy is passed to next level (10% Law).
🔷 6. Ozone Layer & Its Depletion
- Ozone (O₃) in the stratosphere protects us from UV rays.
- Depletion caused by CFCs (Chlorofluorocarbons).
- Effects: Skin cancer, cataracts, crop damage.
🔷 7. Waste & Its Management
- Biodegradable Waste: Can be broken down by microorganisms (e.g., food waste).
- Non-biodegradable Waste: Cannot be broken down easily (e.g., plastic, metals).
🔷 8. Steps to Protect Environment
✅ Reduce, Reuse, Recycle (3Rs)
✅ Avoid plastic, save energy & water
✅ Plant more trees.
📄 Previous Year Questions (Topic-wise)
🌟 Short Answer Questions (1–3 marks)
✅ Define ecosystem with an example.
✅ What is a food chain? Give one example.
✅ What is meant by trophic level?
✅ Name the process responsible for energy transfer in a food chain.
✅ What is ozone and why is it important?
✅ Why are CFCs harmful to the environment?
✅ Differentiate between biodegradable and non-biodegradable substances with examples.
🌟 Long Answer Questions (5 marks)
✅ Explain the flow of energy in an ecosystem. Why is it unidirectional?
✅ Draw a food chain and explain 10% law of energy transfer.
✅ What is ozone layer? Why is it depleting and what are its effects?
✅ Explain the role of decomposers in an ecosystem.
🌟 Diagram-based Questions
✅ Draw a labeled food chain.
✅ Show energy flow through an ecosystem in a pyramid.
✅ Illustrate the 10% law with a diagram.
🌟 HOTS (Higher Order Thinking)
✅ Why is energy flow in an ecosystem always unidirectional?
✅ What would happen if decomposers were removed from the ecosystem?
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✨ Flashcards —
Our Environment
🔷 Flashcard 1
Q: What is an ecosystem?
An ecosystem is the interaction of living (biotic) and non-living (abiotic) components in a specific area.
Example: Pond, forest, desert.
🔷 Flashcard 2
Q: What is a food chain?
A sequence of organisms where one is eaten by the next.
Example: Grass → Grasshopper → Frog → Snake → Hawk
🔷 Flashcard 3
Q: What is a food web?
A network of interconnected food chains in an ecosystem.
🔷 Flashcard 4
Q: Define trophic level.
The position an organism occupies in a food chain.
🔷 Flashcard 5
Q: What is the 10% Law?
Only 10% of energy is transferred from one trophic level to the next; rest is lost as heat.
🔷 Flashcard 6
Q: Why is energy flow in an ecosystem unidirectional?
Because energy comes from the Sun, flows through organisms, and is lost as heat — it doesn’t return to the Sun.
🔷 Flashcard 7
Q: What is the role of decomposers?
Decomposers break down dead organisms and recycle nutrients back to the environment.
🔷 Flashcard 8
Q: What is ozone and why is it important?
Ozone (O₃) in the stratosphere protects Earth from harmful UV rays.
🔷 Flashcard 9
Q: What are CFCs and why are they harmful?
Chlorofluorocarbons are chemicals that destroy the ozone layer.
🔷 Flashcard 10
Q: What is the difference between biodegradable and non-biodegradable waste?
Biodegradable: Decomposed by microbes (e.g., food, paper).
Non-biodegradable: Cannot decompose easily (e.g., plastics, metals).
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