Complete Solutions and Summary of Our Environment – NCERT Class 10, Science, Chapter 13 – Summary, Questions, Answers, Extra Questions

Comprehensive summary and explanation of Chapter 13 'Our Environment', covering the components and structure of ecosystems, food chains and food webs, energy flow in ecosystems, biological magnification, effects of human activities on the environment, ozone layer depletion and its causes, waste management including biodegradable and non-biodegradable substances, disposal methods, and environmental protection strategies—paired with all question answers and extra questions from NCERT Class X Science.

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Categories: NCERT, Class X, Science, Biology, Environment, Ecosystem, Pollution, Biodiversity, Waste Management, Ozone Layer, Chapter 13

Tags: Ecosystem, Food Chain, Food Web, Energy Flow, Biological Magnification, Pollution, Ozone Depletion, Waste Disposal, Biodegradable, Non-biodegradable, Environmental Protection, Human Impact, NCERT, Class 10, Science, Chapter 13, Answers, Extra Questions

Our Environment Class 10 NCERT Chapter 13 - Ultimate Study Guide, Notes, Questions, Quiz 2025

Full Chapter Summary & Detailed Notes - Our Environment Class 10 NCERT

Overview & Key Concepts

Chapter Goal: Understand ecosystem components, interactions, human impacts. Exam Focus: Food chains, ozone depletion, waste. 2025 Updates: Sustainability links. Fun Fact: Only 1% solar energy captured. Core Idea: Balance in nature; humans disrupt. Real-World: Pollution, garbage heaps.
Wider Scope: Conservation, pollution control.

Introduction

Environment discussed in media, elders note changes; healthy work environment; global summits on issues.
Study components interaction, human impact.

13.1 Eco-System — What Are Its Components?

Organisms (plants, animals, microbes, humans) + physical surroundings interact, balance nature.
Ecosystem: Biotic (living) + abiotic (temperature, rain, wind, soil, minerals).
Example: Garden with plants, animals; affected by abiotic.
Natural: Forests, ponds; artificial: Gardens, crop-fields.

Activity 13.1

Design aquarium: Space, water, oxygen, food; add plants/animals for self-sustaining.
Clean periodically; ponds self-clean, not always.

Producers, Consumers, Decomposers

Producers: Green plants, bacteria make food via photosynthesis.
Consumers: Depend on producers; herbivores, carnivores, omnivores, parasites.
Decomposers: Bacteria, fungi break dead/waste to inorganic; replenish soil.

Activity 13.2

Avoid predatory animals in aquarium.
Discuss dependence; form food chain: Algae → Fish → Larger fish.
Producers primary importance.

13.1.1 Food Chains and Webs

Food chain: Series feeding one another; trophic levels.
Producers first; primary, secondary, tertiary consumers.
Energy flow: Unidirectional; 1% captured by plants, 10% to next level.
Chains 3-4 steps; more at lower levels.
Food web: Branching chains.

Energy Flow Diagram

Unidirectional; diminishes each level.

Harmful Chemicals in Food Chain

Pesticides pollute; absorbed by plants/animals.
Biological magnification: Accumulate higher levels.
Humans top; high pesticide in food.

Activity 13.3

Debate bans on high-pesticide foods.
Source: Crops; enter via grains, veggies, meat.
Reduce: Organic farming, washing.

Questions

1. Trophic levels: Example grass → goat → human.
2. Decomposers break waste, replenish soil.

13.2 How Do Our Activities Affect the Environment?

Changes affect us; we pollute.
Focus: Ozone depletion, waste disposal.

13.2.1 Ozone Layer and How it is Getting Depleted

Ozone (O3): Poisonous but shields UV.
UV causes skin cancer.
Formed by UV on O2.
Drop in 1980s from CFCs (refrigerants, fire extinguishers).
UNEP 1987 froze CFC at 1986 levels; now mandatory CFC-free.

Activity 13.4

Chemicals: CFCs deplete ozone.
Regulations reduced hole size.

13.2.2 Managing the Garbage we Produce

Daily waste thrown; perform activity to see changes.

Activity 13.5

Collect home waste; bury, observe 15 days.
Unchanged: Plastics; changed: Food; fastest: Leaves.

Biodegradable and Non-Biodegradable

Enzymes specific; plastics not broken by bacteria.
Biodegradable: Broken biologically; non-biodegradable: Persist, harm ecosystem.

Activity 13.6

Biodegradable: Broken by processes; last long? Centuries for plastics.
New biodegradable plastics: Less harm.

Questions

1. Biodegradable: Broken biologically; non: Not.
2. Biodegradable: Litter, replenish if absent.
3. Non-biodegradable: Pollute soil/water, harm animals.

Garbage Problems

Heaps in towns; tourist spots littered.

Activity 13.7

Home waste collection; local body treats separately?
Daily home/classroom waste; biodegradable portion.
Suggest: Recycle, compost.

Activity 13.8

Sewage treatment; prevent water pollution.
Industries: Treat wastes, avoid soil/water pollution.

Improvements in Lifestyle

More waste; disposables, packaging non-biodegradable.

Think it over: Disposable cups in trains

Plastic to kulhads (soil loss); now paper.
Paper advantages: Biodegradable over plastic.

Activity 13.9

E-waste hazards: Toxic metals; affect soil/water.
Plastics recycling: Melting, remolding; energy use impacts.

Questions

1. Ozone shields UV; affects by damaging life.
2. Reduce: Reuse, recycle.

What you have learnt

Components interdependent.
Producers provide energy; loss limits levels.
Human impact: CFCs endanger ozone.
Waste: Biodegradable/non; disposal problems.

Exercises

1. (c) Fruit-peels, cake, lime-juice.
2. (b) Grass, goat, human.
3. (d) All.
4. Chain breaks; levels affected.
5. Different; no, damage ecosystem.
6. Magnification: Increases up; different levels.
7. Non-biodegradable: Persist, pollute.
8. No; overload decomposers.
9. Damage: UV harm; steps: Ban CFCs.

Why This Guide Stands Out

Complete chapter coverage: Notes, activities, Q&A (all NCERT + extras), quiz. Student-centric, exam-ready for 2025. Free & ad-free.

Key Themes & Tips

Ecosystems: Balance, components.
Energy Flow: 10% rule.
Human Impact: Pollution, depletion.
Tip: Draw chains/webs; understand magnification.

Exam Case Studies

Food chains; ozone; waste effects.

Project & Group Ideas

Survey local waste; model ecosystem; discuss sustainability.

Key Definitions & Terms - Complete Glossary

All terms from chapter; easy to memorize.

Ecosystem

An ecosystem consists of biotic and abiotic components interacting to maintain balance. It includes living organisms and physical surroundings like soil and weather. Example: A pond with fish, plants, and water forming a self-sustaining unit.

Biotic Components

Biotic components are the living parts of an ecosystem, such as plants, animals, and microbes. They interact through food chains and depend on each other for survival. Example: Frogs and insects in a garden ecosystem.

Abiotic Components

Abiotic components are non-living factors like temperature, rainfall, and soil that influence biotic life. They provide the physical environment for organisms. Example: Sunlight and minerals in a forest affecting plant growth.

Producers

Producers are organisms that make food from inorganic substances using sunlight. They form the base of food chains via photosynthesis. Example: Green plants like grasses capturing solar energy.

Consumers

Consumers are organisms that eat producers or other consumers for energy. They are classified as herbivores, carnivores, omnivores. Example: Deer (herbivore) eating plants, lions (carnivore) eating deer.

Decomposers

Decomposers break down dead organisms and waste into inorganic substances. They recycle nutrients back to the soil. Example: Bacteria and fungi decomposing fallen leaves.

Food Chain

A food chain is a linear sequence of organisms where each feeds on the previous. It shows energy transfer through trophic levels. Example: Grass → Goat → Human.

Food Web

A food web is a network of interconnected food chains in an ecosystem. It represents complex feeding relationships. Example: Multiple animals feeding on plants and each other in a forest.

Trophic Level

A trophic level is a step in a food chain based on feeding position. Producers at first, consumers higher. Example: Primary consumers like herbivores at second level.

Biological Magnification

Biological magnification is the increasing concentration of harmful substances up the food chain. Non-degradable chemicals accumulate in higher organisms. Example: Pesticides concentrating in human bodies from crops.

Ozone Layer

The ozone layer is a region in the atmosphere shielding Earth from UV radiation. It is formed by oxygen molecules under UV. Example: Depleted by CFCs, leading to UV exposure risks.

Biodegradable Substances

Biodegradable substances are broken down by biological processes like bacteria. They return to nature without harm if managed. Example: Vegetable peels decomposed into soil nutrients.

Non-Biodegradable Substances

Non-biodegradable substances persist without breaking down biologically. They accumulate and pollute. Example: Plastics lasting centuries in the environment.

Chlorofluorocarbons (CFCs)

CFCs are synthetic chemicals used in refrigerants and aerosols. They deplete the ozone layer when released. Example: Banned globally to protect ozone.

Ultraviolet (UV) Radiation

UV radiation is high-energy sunlight rays harmful to life. Blocked by ozone, causes skin cancer if exposed. Example: Increased UV from ozone hole affecting ecosystems.

Tip: Use flashcards; associate with examples.

60+ Questions & Answers - NCERT Based (Class 10)

Structured as Part A (1 mark, short answers), Part B (4 marks, ~6 lines answers), Part C (8 marks, detailed). 20 per part, based on chapter content, with answers matching the mark scheme.

Part A: 1 Mark Questions (Short Answers)

1. What is an ecosystem?

1 Mark Answer: Biotic + abiotic.

2. Give examples of natural ecosystems.

1 Mark Answer: Forests, ponds.

3. Who are producers?

1 Mark Answer: Green plants.

4. What do decomposers do?

1 Mark Answer: Break waste.

5. What is a food chain?

1 Mark Answer: Feeding series.

6. What percentage of solar energy do plants capture?

1 Mark Answer: 1%.

7. What is the 10% rule in energy flow?

1 Mark Answer: Average transfer.

8. What is biological magnification?

1 Mark Answer: Chemical accumulation.

9. What is ozone?

1 Mark Answer: O3 molecule.

10. What causes ozone depletion?

1 Mark Answer: CFCs.

11. What are biodegradable substances?

1 Mark Answer: Broken biologically.

12. Give an example of non-biodegradable waste.

1 Mark Answer: Plastics.

13. What is a food web?

1 Mark Answer: Branching chains.

14. Why are food chains short?

1 Mark Answer: Energy loss.

15. What shields Earth from UV?

1 Mark Answer: Ozone layer.

16. What agreement froze CFC production?

1 Mark Answer: UNEP 1987.

17. What is the role of decomposers in ecosystem?

1 Mark Answer: Nutrient recycling.

18. Which group contains only biodegradable items?

1 Mark Answer: Fruit-peels, cake, lime-juice.

19. Which constitutes a food chain?

1 Mark Answer: Grass, goat, human.

20. What happens if all organisms in one trophic level are killed?

1 Mark Answer: Chain disrupts.

Part B: 4 Marks Questions (Answers in ~6 Lines)

1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

4 Marks Answer: Steps in food chain. Example: Grass (producer, first), goat (primary consumer, second), human (secondary consumer, third). Energy transfers 10%. Limits chain length.

2. What is the role of decomposers in the ecosystem?

4 Marks Answer: Break dead/waste. Recycle nutrients to soil. Prevent garbage accumulation. Enable plant reuse. Essential balance. Absent: No replenishment.

3. Why are some substances biodegradable and some non-biodegradable?

4 Marks Answer: Enzymes specific. Biodegradable broken biologically. Non-biodegradable persist. Plastics no enzyme match. Natural like food decompose. Synthetics harm long-term.

4. Give any two ways in which biodegradable substances would affect the environment.

4 Marks Answer: Decompose, replenish soil. Overload clogs. Produce gases. Litter temporarily. Recycle nutrients. Positive if managed.

5. Give any two ways in which non-biodegradable substances would affect the environment.

4 Marks Answer: Persist, pollute soil/water. Harm animals ingesting. Accumulate toxins. Block drains. Aesthetic issues. Long-term damage.

6. What is ozone and how does it affect any ecosystem?

4 Marks Answer: O3 shields UV. Depletion increases UV. Harms organisms, cancer. Affects growth. Ecosystem imbalance. Essential protection.

7. How can you help in reducing the problem of waste disposal? Give any two methods.

4 Marks Answer: Reduce, reuse, recycle. Compost biodegradable. Avoid disposables. Segregate waste. Educate others. Sustainable choices.

8. Which of the following groups contain only biodegradable items?

4 Marks Answer: Fruit-peels, cake, lime-juice. All decompose biologically. Others like plastic not. Check natural origins.

9. Which of the following constitute a food-chain?

4 Marks Answer: Grass, goat, human. Producer to consumers. Shows energy flow. Others not sequential.

10. Which of the following are environment-friendly practices?

4 Marks Answer: All: Cloth bags, switch off, walk. Reduce waste/energy. Sustainable habits.

11. What will happen if we kill all the organisms in one trophic level?

4 Marks Answer: Chain breaks. Higher starve. Lower overgrow. Imbalance ecosystem.

12. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

4 Marks Answer: Yes, different. Producers removal collapses all. No, always damage.

13. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

4 Marks Answer: Toxin increase up chain. Yes, higher at top.

14. What are the problems caused by the non-biodegradable wastes that we generate?

4 Marks Answer: Persist, pollute. Harm wildlife. Accumulate toxins.

15. If all the waste we generate is biodegradable, will this have no impact on the environment?

4 Marks Answer: No, overload decomposers. Still litter/gases.

16. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

4 Marks Answer: UV harm life. Ban CFCs.

17. What is a food web?

4 Marks Answer: Interconnected chains. Shows complex relations.

18. Why do food chains generally consist of only three or four steps?

4 Marks Answer: Energy loss great. Little remains.

19. What percentage of food eaten by primary consumers is turned into body?

4 Marks Answer: 10% average.

20. What are abiotic components? Give examples.

4 Marks Answer: Non-living: Temperature, soil.

Part C: 8 Marks Questions (Detailed Answers)

1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

8 Marks Answer: Trophic levels are steps in a food chain representing energy positions. Producers at first fix solar energy. Primary consumers (herbivores) at second eat producers. Secondary consumers (carnivores) at third eat primaries. Tertiary at fourth eat secondaries. Example: In grassland - Grass (producer, first level), deer (primary consumer, second), lion (secondary consumer, third). Energy flows unidirectionally with 10% transfer average, limiting levels to 3-4 as loss is high. This maintains balance; disruption affects all.

2. What is the role of decomposers in the ecosystem?

8 Marks Answer: Decomposers like bacteria and fungi break down dead organisms and wastes into simple inorganic substances. These go into soil, replenishing nutrients for plants. Without them, garbage accumulates, soil depletes, and natural recycling stops. They complete the cycle, ensuring producers get minerals. In absence, ecosystems collapse as nutrients lock in dead matter. Essential for balance, they prevent disease from decay and support life continuity.

3. Why are some substances biodegradable and some non-biodegradable?

8 Marks Answer: Enzymes in decomposers are specific, breaking particular substances. Biodegradable like food wastes match enzymes, decomposed into inorganics. Non-biodegradable like plastics lack matching enzymes, persist under ambient conditions. Physical processes like heat affect but slowly. Synthetics designed for durability resist biology. This leads to accumulation; biodegradable recycle naturally if not overloaded, while non harm ecosystems long-term.

4. Give any two ways in which biodegradable substances would affect the environment.

8 Marks Answer: Biodegradable substances decompose, releasing nutrients to soil, aiding plant growth and cycle. However, excess like garbage heaps produce methane, contributing to warming. They can litter temporarily, affecting aesthetics and wildlife until broken. If unmanaged, overload decomposers, causing smells and disease. Positive: Compost enriches soil. Overall, minimal harm if handled, but large quantities disrupt balance.

5. Give any two ways in which non-biodegradable substances would affect the environment.

8 Marks Answer: Non-biodegradable persist, polluting soil and water, leaching toxins over time. Animals ingest, causing death or chain magnification. Block drains, cause floods; accumulate in oceans, harm marine life. Aesthetic degradation in heaps; microplastics enter food. Long-term, alter habitats, reduce biodiversity. No natural breakdown means perpetual issues unless recycled.

6. What is ozone and how does it affect any ecosystem?

8 Marks Answer: Ozone (O3) is a triatomic oxygen molecule, poisonous at ground but protective in atmosphere. Shields UV radiation, preventing skin cancer and organism damage. Depletion increases UV, harming photosynthesis, growth, and leading to mutations. Ecosystems suffer reduced productivity, altered chains. Formed by UV on O2; CFCs deplete it. Affects all life, disrupting balance.

7. How can you help in reducing the problem of waste disposal? Give any two methods.

8 Marks Answer: Reduce waste by using reusables like cloth bags, avoiding disposables. Recycle materials like paper and plastics to conserve resources and lessen landfill. Compost biodegradable for nutrient-rich soil, reducing garbage volume. Segregate at source for efficient treatment. Educate on 3Rs; support policies. These minimize environmental impact, promote sustainability.

8. Which of the following groups contain only biodegradable items?

8 Marks Answer: Fruit-peels, cake, lime-juice are all biodegradable, broken by decomposers into inorganics. Grass, flowers, leather also, but plastic in others makes non. Wood decomposes slowly but biologically. Check for natural origins vs synthetics. This distinguishes waste management needs.

9. Which of the following constitute a food-chain?

8 Marks Answer: Grass, goat, human forms a chain: Producer to primary to secondary consumer. Shows energy flow. Others like grass, wheat, mango lack sequence. Goat, cow, elephant are all primaries. Proper chain has trophic progression.

10. Which of the following are environment-friendly practices?

8 Marks Answer: All: Carrying cloth-bags reduces plastic; switching off saves energy; walking cuts emissions. These minimize waste, conserve resources, lower pollution. Promote sustainability; small actions cumulative impact.

11. What will happen if we kill all the organisms in one trophic level?

8 Marks Answer: Ecosystem collapses: Higher levels starve, die; lower overpopulate, deplete resources. Example: No producers, all consumers perish. Balance lost; biodiversity reduces. Recovery difficult; shows interdependence.

12. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

8 Marks Answer: Yes, different: Removing producers affects all; top predators less immediate but controls lower. No level removable without damage; disrupts flow, magnification. Interdependence means any removal imbalances.

13. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

8 Marks Answer: Increasing toxin concentration up chain as non-degradable substances accumulate. Yes, low at producers, max at top like humans. Pesticides example: From plants to fish to birds. Harms health, ecosystems.

14. What are the problems caused by the non-biodegradable wastes that we generate?

8 Marks Answer: Persist centuries, fill landfills, pollute water/soil. Toxins leach, enter chains. Wildlife chokes/ingests. Microplastics in food. Aesthetic, health issues; recycling needed but incomplete.

15. If all the waste we generate is biodegradable, will this have no impact on the environment?

8 Marks Answer: No, large amounts overload decomposers, cause smells, gases like methane warming climate. Litter spreads disease. Proper management like composting needed; unmanaged still harms.

16. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

8 Marks Answer: Allows UV, causing cancer, mutations, reduced productivity. Concern: Harms all life. Steps: Ban CFCs via UNEP 1987; CFC-free products mandatory. Monitoring hole size.

17. Explain the energy flow in an ecosystem.

8 Marks Answer: Unidirectional from sun to producers (1% captured), 10% to consumers, lost as heat. Diminishes levels; chains short. Diagram: Sun → Producers → Herbivores → Carnivores. Supports life; loss in forms unusable.

18. What is a food web? How is it different from a food chain?

8 Marks Answer: Network of chains showing complex relations. Chain linear; web branching, realistic. Example: Multiple predators per prey. More stable; one break less impact.

19. Describe biological magnification with an example.

8 Marks Answer: Toxins accumulate up chain as non-degradable. Example: Pesticides in water to plants (low), fish (medium), humans (high). Max at top; health risks like residues in food.

20. How do human activities affect the environment?

8 Marks Answer: Pollute via chemicals, deplete ozone with CFCs, generate non-biodegradable waste. Changes lifestyle increase disposables. Impacts: Imbalance, health issues. Mitigation: Regulations, sustainable practices.

Practice Tip: Time yourself; draw diagrams for long Q.

All Textbook Activities - Practical Learning Step by Step

Complete list with steps, observations, conclusions.

Activity 13.1: Designing an Aquarium

Steps: 1. Think of things needed: Free space (jar), water, oxygen (aerator), food. 2. Add aquatic plants and animals for self-sustaining. 3. Set up and observe. 4. Clean periodically; compare to ponds.
Observations: Plants provide oxygen/food; system balances if not overfed. Needs cleaning as wastes accumulate unlike natural ponds with more decomposers.
Conclusion: Aquarium is artificial ecosystem; requires maintenance. Shows interdependence; natural ones self-regulate better.

Activity 13.2: Aquatic Food Chain

Steps: 1. Avoid animals eating others in aquarium. 2. Group discuss dependence. 3. Form chain: Algae → Small fish → Larger fish (at least three steps). 4. Consider primary group importance.
Observations: Organisms interdependent; producers base. Without, chain collapses.
Conclusion: All groups dependent; producers primary as energy source. Shows balance need.

Activity 13.3: Pesticides in Food

Steps: 1. Debate bans on high-pesticide foods. 2. Source: Crops via soil/water. 3. Enter bodies through grains, veggies, meat. 4. Methods to reduce: Organic, wash, peel.
Observations: Reports show residues; bans in states. Multiple entry points.
Conclusion: Pesticides magnify; need reduction for health. Supports regulation.

Activity 13.4: Ozone Depleting Chemicals

Steps: 1. Find chemicals: CFCs. 2. Regulations: UNEP 1987 froze production. 3. Success: Reduced damage, hole size changed less recently.
Observations: CFCs in refrigerants; global agreement effective.
Conclusion: Human actions deplete; controls work. Hole stabilizing.

Activity 13.5: Waste Burial

Steps: 1. Collect waste: Food, paper, bottles, clothes. 2. Bury in pit/bucket with soil. 3. Keep moist; observe 15-day intervals. 4. Note unchanged/changed/fastest.
Observations: Plastics unchanged; food changed; leaves fastest.
Conclusion: Biodegradable change form; non persist. Shows decomposition rates.

Activity 13.6: Biodegradable vs Non-Biodegradable

Steps: 1. Research biodegradable/non. 2. Non last: Plastics centuries. 3. New biodegradable plastics: Break faster, less harm.
Observations: Biodegradable decompose; non inert/harmful.
Conclusion: New plastics eco-friendly; reduce impact.

Activity 13.7: Waste Generation

Steps: 1. Home waste system. 2. Local body treatment: Separate bio/non. 3. Calculate daily home/classroom waste; biodegradable portion. 4. Suggest dealing: Compost, recycle.
Observations: Much biodegradable; systems vary.
Conclusion: Awareness reduces; separation key.

Activity 13.8: Sewage and Industrial Waste

Steps: 1. Local sewage treatment: Prevent water pollution. 2. Industries: Treat wastes, avoid soil/water pollution.
Observations: Mechanisms exist; enforcement varies.
Conclusion: Proper treatment essential; prevents contamination.

Activity 13.9: E-Waste and Plastics

Steps: 1. Hazardous in e-waste: Metals like lead; affect environment toxically. 2. Plastics recycling: Melt, remold; energy impact.
Observations: Toxins leach; recycling reduces but pollutes.
Conclusion: E-waste harms; recycling mitigates but not fully.

Lab Tip: Record observations; draw charts.

Level	Description	Example	Energy
Producers	Make food from sun	Plants	1% solar
Primary Consumers	Eat producers	Herbivores like deer	10% from previous
Secondary Consumers	Eat primaries	Carnivores like fox	10% from previous
Tertiary Consumers	Eat secondaries	Top like lion	10% from previous
Decomposers	Break wastes	Bacteria	Recycle