CBSE Class 10 Science Revision Notes Chapter 13 Our Environment 2026–27
Our Environment explains how living organisms and non-living factors interact to maintain balance in nature. CBSE Class 10 Science Chapter 13 covers ecosystems, food chains, trophic levels, ozone depletion and waste disposal.
Our Environment explains how plants, animals, microorganisms, human beings and physical surroundings interact with each other. The chapter shows how energy flows through ecosystems and how human activities affect natural balance.
Use these CBSE Class 10 Science Revision Notes Chapter 13 for the 2026–27 academic year to revise ecosystem components, food chains, food webs, energy transfer, biological magnification, ozone layer depletion and waste disposal. Focus on definitions, examples, tables and process-based notes.
Key Takeaways
- Ecosystem: An ecosystem includes living organisms and non-living surroundings that interact with each other.
- Food chain: A food chain shows how energy passes from one organism to another.
- 10 percent law: Only about 10% of energy is transferred to the next trophic level.
- Waste disposal: Biodegradable and non-biodegradable wastes affect the environment differently.
Struggling with food chains, trophic levels, ozone depletion and waste management examples?
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CBSE Class 10 Science Revision Notes Chapter 13 on Our Environment: Chapter Overview
Environment includes everything that surrounds and affects living organisms. It includes living organisms, physical surroundings and natural resources.
| Concept | Meaning | Example |
| Environment | Surroundings that affect organisms | Air, water, soil, plants, animals |
| Ecosystem | Living and non-living components interacting together | Forest, pond, garden |
| Biotic components | Living components of an ecosystem | Plants, animals, microorganisms |
| Abiotic components | Non-living physical factors | Temperature, rainfall, soil, minerals |
| Balance in nature | Stable interaction between organisms and surroundings | Producers, consumers and decomposers working together |
A garden is an ecosystem because plants, insects, birds, soil, water, air and sunlight interact with one another.
Important Topics in CBSE Notes Class 10 Science Chapter 13 Our Environment
Class 10 Science Chapter 13 Notes focus on ecosystem balance and human impact on the environment.
| Important Topic | What to Revise | Key Terms |
| Ecosystem | Biotic and abiotic components | Garden, pond, forest |
| Producers | Organisms that make food | Green plants |
| Consumers | Organisms that depend on others for food | Herbivores, carnivores |
| Decomposers | Organisms that break down dead matter | Bacteria, fungi |
| Food chain | Feeding sequence | Grass → Goat → Human |
| Food web | Network of food chains | Interconnected feeding links |
| Trophic levels | Steps in a food chain | Producer, primary consumer |
| Energy flow | Transfer of energy in ecosystem | 10 percent law |
| Biological magnification | Increase of harmful chemicals | Pesticides in food chain |
| Ozone layer depletion | Damage to ozone shield | CFCs |
| Waste disposal | Managing waste safely | Biodegradable, non-biodegradable |
This chapter is best revised through definitions, examples and comparison tables.
Our Environment Class 10 Notes: Ecosystem and Its Components
An ecosystem is formed by all organisms in an area and the non-living factors around them. Both components influence each other.
| Type of Ecosystem | Meaning | Example |
| Natural ecosystem | Exists naturally without human maintenance | Forest, pond, lake |
| Artificial ecosystem | Made or maintained by humans | Garden, crop-field, aquarium |
A pond does not need regular cleaning like an aquarium because natural decomposers and other organisms help recycle matter. An aquarium is human-made, so it needs external care.
Biotic and Abiotic Components in Class 10 Science Chapter 13 Notes
| Component | Meaning | Examples |
| Biotic components | Living organisms in an ecosystem | Plants, animals, bacteria, fungi |
| Abiotic components | Non-living physical factors | Temperature, rainfall, wind, soil, minerals |
Biotic and abiotic components together decide the growth, reproduction and survival of organisms in an ecosystem.
Producers, Consumers and Decomposers in CBSE Class 10 Science Revision Notes Chapter 13
Organisms are grouped as producers, consumers and decomposers according to how they obtain food.
| Group | Meaning | Examples |
| Producers | Make food from inorganic substances using sunlight and chlorophyll | Green plants, some bacteria |
| Consumers | Depend directly or indirectly on producers for food | Animals, humans |
| Decomposers | Break down dead organisms and wastes into simpler substances | Bacteria, fungi |
Producers form the base of the ecosystem. Consumers depend on producers directly or indirectly. Decomposers recycle nutrients back into the soil.
Types of Consumers in Our Environment Class 10 Notes
| Type of Consumer | Food Habit | Examples |
| Herbivores | Eat plants | Goat, deer, grasshopper |
| Carnivores | Eat animals | Lion, frog, snake |
| Omnivores | Eat plants and animals | Human beings, crow, dog |
| Parasites | Live on or inside another organism for food | Tapeworm, lice |
Consumers cannot prepare their own food. They depend on producers or other consumers.
Role of Decomposers in Ecosystem Notes
Decomposers break down dead remains and waste products. They convert complex organic substances into simpler inorganic substances.
| Role of Decomposers | Why It Matters |
| Break down dead plants and animals | Prevents accumulation of dead matter |
| Recycle nutrients | Returns minerals to soil |
| Maintain soil fertility | Helps plants grow again |
| Complete nutrient cycling | Keeps ecosystem functional |
Without decomposers, dead organisms and waste would keep accumulating. Natural replenishment of soil would also reduce.
Food Chains and Food Webs in Class 10 Science Chapter 13 Notes
A food chain is a sequence of organisms in which one organism eats another. It shows transfer of food and energy.
| Food Chain Example | Trophic Level |
| Grass | Producer |
| Deer | Primary consumer |
| Lion | Secondary consumer |
Another example:
Grass → Grasshopper → Frog → Snake → Hawk
Each step in a food chain is called a trophic level.
Trophic Levels in CBSE Notes Class 10 Science Chapter 13
| Trophic Level | Organism Type | Example |
| First trophic level | Producers | Green plants |
| Second trophic level | Primary consumers | Herbivores |
| Third trophic level | Secondary consumers | Small carnivores |
| Fourth trophic level | Tertiary consumers | Larger carnivores |
Producers capture solar energy and make it available to consumers. Energy then passes from one trophic level to the next.
Food Chain and Food Web Difference Table
| Food Chain | Food Web |
| Single feeding pathway | Network of many food chains |
| Simple and straight | More complex |
| One organism usually linked to one next organism | One organism may have many food links |
| Less stable | More stable |
A food web shows the real feeding relationships in an ecosystem. Most organisms are eaten by more than one kind of organism and also eat more than one food source.
Energy Flow and 10 Percent Law in Our Environment Class 10 Notes
Energy flow in an ecosystem is unidirectional. Energy captured by producers does not return to the Sun. Energy passed to herbivores does not return to producers.
| Step | Energy Movement |
| Sunlight | Main source of energy |
| Producers | Capture solar energy and make food |
| Primary consumers | Get energy by eating producers |
| Secondary consumers | Get energy by eating primary consumers |
| Decomposers | Use energy from dead matter and wastes |
Green plants in a terrestrial ecosystem capture about 1% of the sunlight falling on their leaves.
10 Percent Law in Class 10 Science Chapter 13 Notes
According to the 10 percent law, only about 10% of energy at one trophic level is transferred to the next trophic level.
| Trophic Level | Energy Available Example |
| Producers | 10,000 J |
| Primary consumers | 1,000 J |
| Secondary consumers | 100 J |
| Tertiary consumers | 10 J |
Most energy is lost as heat, used in digestion, movement and other life processes.
Food chains usually have only three or four steps because very little usable energy remains after several trophic levels.
Biological Magnification in CBSE Class 10 Science Revision Notes Chapter 13
Biological magnification is the increase in concentration of harmful non-biodegradable chemicals at each trophic level.
Pesticides and other chemicals used in fields may enter soil and water. Plants absorb them with water and minerals. Aquatic plants and animals may also take them from water bodies.
| Stage | What Happens |
| Chemicals enter soil or water | Pesticides get washed into the environment |
| Producers absorb chemicals | Plants take them with water and minerals |
| Consumers eat producers | Chemicals enter animal bodies |
| Higher consumers eat lower consumers | Chemical concentration increases |
| Humans occupy top levels | Maximum concentration may accumulate in the body |
These chemicals are not easily broken down. They accumulate progressively at higher trophic levels.
Ozone Layer Depletion in Our Environment Class 10 Notes
Ozone is a molecule made of three oxygen atoms. Its formula is O₃.
At higher levels of the atmosphere, ozone protects Earth from harmful ultraviolet radiation from the Sun. UV radiation can damage organisms and may cause skin cancer in humans.
Formation of Ozone in Class 10 Science Chapter 13 Notes
Ozone forms when ultraviolet radiation acts on oxygen molecules.
| Step | Process |
| 1 | UV radiation splits oxygen molecule |
| 2 | Free oxygen atoms are formed |
| 3 | Oxygen atom combines with oxygen molecule |
| 4 | Ozone is formed |
Reaction form:
O₂ → O + O
O + O₂ → O₃
Causes and Effects of Ozone Layer Depletion
| Cause or Effect | Explanation |
| Main cause | Chlorofluorocarbons or CFCs |
| Earlier use of CFCs | Refrigerants and fire extinguishers |
| Effect of ozone depletion | More UV radiation reaches Earth |
| Harmful impact | Skin cancer and damage to organisms |
| Control step | CFC production was controlled internationally |
The amount of ozone began to drop sharply in the 1980s. This decrease was linked with synthetic chemicals such as CFCs.
Biodegradable and Non-Biodegradable Waste in CBSE Notes Class 10 Science Chapter 13
Waste materials may be biodegradable or non-biodegradable. The difference depends on whether biological processes can break them down.
| Type of Waste | Meaning | Examples |
| Biodegradable waste | Broken down by biological processes | Vegetable peels, paper, food waste |
| Non-biodegradable waste | Not broken down easily by biological processes | Plastic, glass, metal cans |
Enzymes are specific in their action. Many human-made materials, such as plastics, are not broken down by bacteria or other saprophytes under normal environmental conditions.
Difference Between Biodegradable and Non-Biodegradable Substances
| Biodegradable Substances | Non-Biodegradable Substances |
| Decompose naturally | Persist for a long time |
| Broken down by microorganisms | Not easily broken down by microorganisms |
| Return nutrients to environment | May pollute soil, water and air |
| Usually cause short-term waste load | Can cause long-term environmental damage |
Non-biodegradable substances may remain unchanged for long periods. Some may also harm different members of the ecosystem.
Waste Disposal in Class 10 Science Chapter 13 Notes
Human activities generate large amounts of waste. Changes in lifestyle and packaging have increased non-biodegradable waste.
| Waste Source | Examples |
| Kitchen waste | Vegetable peels, spoilt food, used tea leaves |
| Packaging waste | Milk packets, empty cartons, wrappers |
| Medical waste | Empty medicine bottles, used strips |
| Household waste | Old clothes, broken footwear |
| Electronic waste | Discarded electronic items |
Waste disposal becomes a serious problem when waste is not separated, treated or recycled properly.
How Waste Affects the Environment
| Waste Type | Environmental Effect |
| Biodegradable waste in excess | Bad smell, growth of disease-causing organisms |
| Plastic waste | Persists in soil and water |
| Chemical waste | Pollutes soil and water |
| Untreated sewage | Pollutes water bodies |
| Electronic waste | May release hazardous materials |
Waste management needs segregation of biodegradable and non-biodegradable waste. Local bodies also need systems to treat sewage and industrial waste before release.
Ways to Reduce Waste Disposal Problems
| Method | How It Helps |
| Separate waste at source | Makes treatment easier |
| Compost biodegradable waste | Converts organic waste into manure |
| Reduce disposable items | Lowers waste generation |
| Reuse materials | Extends product life |
| Recycle suitable waste | Reduces pressure on landfills |
Reducing waste generation is better than dealing with waste after it is produced.
Important Points of CBSE Class 10 Science Chapter 13 Our Environment
These quick notes cover the main facts from Our Environment Class 10 Notes.
| Concept | Important Point |
| Ecosystem | Includes biotic and abiotic components |
| Producers | Make food using sunlight and chlorophyll |
| Consumers | Depend on producers directly or indirectly |
| Decomposers | Break down dead matter and recycle nutrients |
| Food chain | Shows who eats whom |
| Food web | Network of interconnected food chains |
| Trophic level | Step in a food chain |
| Energy flow | Unidirectional in an ecosystem |
| 10 percent law | About 10% energy reaches the next level |
| Biological magnification | Harmful chemicals increase at higher trophic levels |
| Ozone | O₃ molecule that protects from UV radiation |
| CFCs | Chemicals linked with ozone depletion |
| Biodegradable waste | Broken down by biological processes |
| Non-biodegradable waste | Persists for long periods |
| Waste disposal | Needs segregation, treatment and reduction |
Useful Links for Class 10 Science
| Section | Useful Links |
| NCERT Solutions | NCERT Solutions for Class 10 Science |
| Important Questions | Important Questions Class 10 Science |
| Previous Year Papers | CBSE Science Question Paper Class 10 |
| NCERT Books | NCERT Books for Class 10 Science |
| Revision Notes | CBSE Class 10 Science Revision Notes |
| Syllabus | CBSE Class 10 Science Syllabus |
| Sample Papers | CBSE Sample Papers for Class 10 Science |
CBSE Class 10 Science Revision Notes
FAQs (Frequently Asked Questions)
An ecosystem is a system where living organisms interact with each other and with non-living surroundings. A pond, forest, garden and aquarium are examples of ecosystems.
Trophic levels are the different steps in a food chain. Producers form the first trophic level, herbivores form the second level, and carnivores occupy higher levels.
Decomposers break down dead plants, animals and wastes into simpler substances. This recycles nutrients back into soil and helps maintain ecosystem balance.
Biological magnification is the increase in concentration of harmful non-biodegradable chemicals at each trophic level. Humans may receive the highest concentration because they often occupy top levels in food chains.
The ozone layer absorbs harmful ultraviolet radiation from the Sun. This protects living organisms from damage and reduces harmful effects such as skin cancer in humans.