TEACHGYAN • CLASS 10 SCIENCE • NCERT 2026–27
Chapter 13: Our Environment
Detailed Notes • Diagrams • Experiments • Competency • Board Practice
📖 Chapter Explanation
Ecosystems contain interacting living organisms and physical components. The chapter develops food chains, trophic levels, energy flow, biological magnification and the role of decomposers, while connecting environmental protection with waste management.
🧭 Concept Map
🔬 Core Science
Energy flows through an ecosystem from producers to consumers and decomposers. Only a small fraction of energy is transferred to the next trophic level, so food chains generally contain limited trophic levels.
🖼️ Diagram / Visual Study
Draw a clean labelled diagram showing direction/arrows, components and the scientific relationship involved.
💡 Worked/Applied Example
Non-biodegradable substances can persist and may become increasingly concentrated at higher trophic levels through biological magnification.
⚠️ Common Errors
Do not confuse food chains with food webs. Also, decomposers are not simply ‘waste eaters’; they recycle nutrients by breaking down organic matter.
🧠 Concept-Based MCQs
- The first trophic level is occupied by: A) producers B) herbivores C) carnivores D) decomposers
- Energy transfer between trophic levels is: A) complete B) limited C) always 100% D) impossible
- A biodegradable material is generally: A) broken down by biological processes B) always plastic C) radioactive D) a metal
- Biological magnification is most likely for: A) persistent non-biodegradable pollutants B) oxygen C) sunlight D) water
Answer Key: 1-A, 2-B, 3-A, 4-A.
📊 Case-Based / Competency
A pesticide enters a pond ecosystem. Students trace its movement through a food chain and explain why organisms at higher trophic levels may be exposed to greater concentrations.
- Identify the scientific principle.
- Represent the situation with a diagram/model.
- Apply the relevant law or concept.
- Interpret and verify the conclusion.
🔎 Extension Case
A lake receives persistent pesticide residues. Students construct a food chain, identify trophic levels and explain why pollutant concentration can increase toward higher-level consumers.
🧪 Activity / Observation Corner
Plan a safe classroom observation or demonstration related to the chapter. Record the objective, materials, procedure, observation and inference. Follow teacher/laboratory safety instructions for any practical work.
🔥 HOTS & Board Challenge
- Explain why the phenomenon occurs.
- Predict what changes if one variable is altered.
- Find and correct a plausible incorrect explanation.
- Apply the concept to a real-life situation.
✍️ Exam Practice
- Define the central concept.
- Answer a diagram-based question.
- Solve a numerical/application question.
- Explain an experiment or real-life application.
- Write a complete 5-mark answer with scientific reasoning.
📄 Practice Worksheet
- 5 concept checks
- 5 application questions
- 3 diagram-based questions
- 2 case-based questions
- 2 HOTS questions
- 1 board-style challenge
🎯 One-Minute Revision
organisms + physical factors → ecosystem → food chain/web → trophic levels → energy flow → environmental impact
🏆 Mastery Checklist
- ☐ I can explain the concept scientifically.
- ☐ I can draw and label the key diagram.
- ☐ I can apply the concept to a new situation.
- ☐ I can solve competency/case-based questions.
- ☐ I can justify my conclusion.
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Original explanatory study material aligned to the current NCERT/CBSE framework; textbook passages are not reproduced verbatim.
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