Our Environment

Class 10 CBSE Science • Chapter 13 • Easy, colourful notes for kids

Environment Ecosystem Components Trophic levels Food chain & web Energy flow Ozone Garbage Magnification Revision

1. What is the Environment?

The environment is everything around an organism. It includes both living (biotic) and non-living (abiotic) elements.

These factors interact in complex ways, and our actions greatly impact the environment.

Biotic

living things

Abiotic

non-living things

2. Ecosystem

Ecosystem: a community of living organisms interacting with their non-living surroundings. Examples: a pond or a forest.

Ecosystems keep a balance through a constant exchange of energy and matter.
Natural ecosystems: forest, pond, grassland.
Human-made (artificial) ecosystems: garden, crop field, aquarium.

3. Components of an Ecosystem

Biotic components (living)

Producers (Autotrophs)

Make their own food. Plants and some bacteria use sunlight by photosynthesis. Phytoplanktons are tiny floating water plants that make food.

Consumers (Heterotrophs)

Get food by eating others.

Decomposers (Saprotrophs)

Fungi and bacteria. They break down dead organic matter and recycle nutrients back into the soil.

Types of consumers

Type	Eats	Example
Herbivores (primary consumers)	Plants	Deer
Carnivores (primary, secondary or tertiary)	Other animals	Lion
Omnivores	Both plants and animals	Humans

Decomposers are vital for keeping the environment clean and fertile.

Abiotic components (non-living)

Factors	Examples
Physical	Soil type, water, air, landforms
Chemical	Carbon dioxide, oxygen, nitrogen, minerals like phosphorus and calcium
Climatic	Sunlight, temperature, rainfall, humidity (they affect how organisms live and spread)

4. Trophic Levels

Trophic levels are the feeding positions in a food chain. Energy transfers from one level to the next.

Level	Who	Eats
1st	Producers (plants)	Make their own food
2nd	Primary consumers (herbivores)	Producers
3rd	Secondary consumers (carnivores)	Herbivores
4th	Tertiary consumers (carnivores)	Other carnivores

🔗 5. Food Chain and Food Web

Food chain: shows how energy flows from one organism to another. Each organism feeds on the one below it.

Grass
Producer

➔

Deer
Primary consumer

➔

Lion
Secondary consumer

Energy moves in one direction only.
Harmful chemicals can also move up the food chain.

Food web: a network of interconnected food chains. It shows complex feeding relationships. An organism often has multiple food sources and predators.

Plants

➔

Insects / Rabbit / Mouse

➔

Frog / Snake

➔

Eagle

Many food chains linked together make a food web. For example, the eagle can eat the snake, the rabbit or the mouse.

6. Energy Flow

Energy moves through the trophic levels.
Green plants capture about 1% of solar energy.
Only 10% of the energy from one trophic level passes to the next. The remaining 90% is used up or lost as heat.

10% law: 1000 J → 100 J → 10 J → 1 J

Tip: Because so much energy is lost at each step, food chains are short (usually 3 to 4 steps).

7. Environmental Problem: Ozone Layer Depletion

The ozone layer (O₃) in the stratosphere protects Earth from harmful UV radiation.
Chlorofluorocarbons (CFCs) from refrigerants and aerosols deplete this layer.
Ozone depletion causes skin cancer and other health issues.
The Montreal Protocol aimed to reduce CFC use.

How ozone forms: UV rays split oxygen (O₂) into oxygen atoms. Each atom joins an O₂ molecule to make ozone (O₃).

O₂ —(UV)→ O + O
O + O₂ → O₃ (ozone)

8. Garbage Management

Effective waste management is important.

Biodegradable waste

Breaks down naturally.
Examples: food scraps, paper.

Non-biodegradable waste

Does not break down naturally. Causes significant pollution.
Examples: plastics, metals, DDT.

Methods of waste disposal

Method	Meaning
Incineration	Burning waste at high temperatures
Landfilling	Burying waste in designated areas
Composting	Converting organic waste into manure
Recycling	Processing waste materials to make new products
Reuse	Using items multiple times

9. Biological Magnification

Biological magnification: the increase in concentration of harmful chemical substances, like pesticides, as they move up the food chain. The highest concentrations appear in the top predators.

Non-biodegradable chemicals such as DDT are not broken down, so they build up in the bodies of animals at higher trophic levels.

10. Quick Revision

Ecosystem

Living things + non-living surroundings

Producers

Make their own food

Decomposers

Fungi and bacteria, recycle nutrients

Trophic levels

Producers → Primary → Secondary → Tertiary

Energy flow

Only 10% passes to the next level

Ozone (O₃)

Blocks UV; CFCs deplete it

Montreal Protocol

Reduce CFC use

Biodegradable

Food scraps, paper

Non-biodegradable

Plastics, metals, DDT

Biological magnification

Chemicals rise up the food chain

All the best for your exams! 🌟

class 10 Biology : our environment : notes