NCERT Curiosity · Class 8 · Science
How Nature Works in Harmony
Elephants wander into farms and villages as their forest habitat shrinks — a sign of how closely everything in nature connects.
Food Chains Food Webs Symbiosis Ecosystems
Key idea
Habitats: Biotic and Abiotic
Biotic

The living things in a habitat — plants, animals, and microbes.

Abiotic

The non-living things — air, water, soil, temperature, sunlight.

Key idea
Population and Community
Population

A group of the same kind of organism, living together in a habitat.

Community

All the different populations sharing a habitat, depending on each other.

Key idea
Producers, Consumers, and Decomposers

Producers

Make their own food via photosynthesis — green plants.

Consumers

Depend on others for food — herbivores, carnivores, omnivores.

Decomposers

Break down dead matter, recycling nutrients — fungi, bacteria.

Key idea
A Food Chain
Grass
→
Grasshopper
→
Frog
→
Snake
→
Eagle
Key idea
Real ecosystems rarely have just one food chain.
Many chains interlink into a food web, because most animals eat — and are eaten by — more than one other kind. Organism numbers typically shrink going up each level, forming a pyramid.
Key idea
Mutualism, Commensalism, and Parasitism

Mutualism

Both benefit — honeybees and flowers.

Commensalism

One benefits, the other unaffected — orchids on trees.

Parasitism

One benefits, the other is harmed — ticks on dogs.

Key idea
One disruption can set off a chain reaction.
Pollution killing pond plants means less oxygen, dying fish, fewer consumers, more insects, and more pesticide use — each step causing the next.
Key idea
The Sundarbans, the world's largest mangrove forest, protects coastlines from storms.
Ecosystems give us fresh air, fertile soil, food, and medicine — but the Sundarbans faces threats from logging, hunting, and pollution.
Key idea
The Green Revolution, and Monoculture
Green Revolution

Boosted food production in the 1950s–60s, but overuse now degrades soil and biodiversity.

Monoculture

Growing the same crop repeatedly reduces biodiversity and harms pollinators.

Chapter · key terms to remember
Key Terms

Habitat

The place providing conditions for an organism to live.

Population / Community

Same species / all species sharing a habitat.

Ecosystem

Biotic and abiotic components interacting.

Chapter · key terms to remember
More Key Terms

Producers / Consumers / Decomposers

Make food / eat others / recycle waste.

Food chain / web

Who eats whom / interlinked food chains.

Trophic level

An organism's feeding position in a food chain.

Chapter · key terms to remember
More Key Terms

Mutualism / Commensalism / Parasitism

Both benefit / one benefits / one harmed.

Monoculture

Growing the same crop repeatedly.

Opening

Jump to a section — tap anywhere else to close