Biodiversity & Conservation Zones

Syllabus Unit: Environment & Ecology

Why it matters

Chapter overview

India is one of the world's 17 megadiverse countries and hosts 4 of the planet's 36 recognised biodiversity hotspots. This topic covers how ecosystems function, where India's richest and most threatened biodiversity is concentrated, the protected-area network built to conserve it, and the legal framework — the Wildlife (Protection) Act, 1972 and its flagship species-recovery projects — that gives that conservation teeth.

General Studies Paper I Environment & Ecology 12%–15% weightage

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1Producers capture solar energy

2Primary consumers (herbivores) eat producers

3Secondary/tertiary consumers eat other consumers

4Decomposers return nutrients to soil

1Ecosystems & Biomes

Every ecosystem, from a puddle to a rainforest, runs on the same three-part engine: producers capture energy, consumers move it up the food chain, and decomposers return it to the soil.

Learning Objectives

Define an ecosystem and distinguish its biotic and abiotic components.
Explain the roles of producers, consumers and decomposers in energy flow through an ecosystem.
State Lindeman's 10% law of trophic energy transfer and its implication for food chain length.
Classify the world's major biomes (forest, grassland, desert, aquatic) by temperature and precipitation.

Key Terms

ProducersAutotrophic organisms (green plants, algae, cyanobacteria) that convert solar energy into chemical energy via photosynthesis, forming the base of every food chain.

DecomposersBacteria and fungi that break down dead organic matter, releasing nutrients back into the soil for producers to reuse — closing the nutrient cycle.

10% Law (Lindeman's Law)Only about 10% of energy at one trophic level is transferred to the next; the rest is lost as heat/metabolism, which limits food chains to typically 4-5 levels.

BiomeA large-scale ecological community defined by climate (temperature and precipitation) and dominant vegetation, e.g. tropical rainforest, savanna, tundra.

An **ecosystem** is a self-sustaining unit of interacting biotic (living) and abiotic (non-living: sunlight, soil, water, temperature) components. Every ecosystem — pond, forest or grassland — runs on the same structural engine of energy and nutrient flow.

The three functional roles in every ecosystem

Producers (autotrophs) — green plants and algae that fix solar energy into chemical energy through photosynthesis; the entry point of all energy into the system.
Consumers (heterotrophs) — primary consumers (herbivores) eat producers; secondary/tertiary consumers (carnivores) eat other consumers, forming the food chain.
Decomposers — bacteria and fungi that break down dead matter and waste, releasing nutrients back into the soil for producers to reuse, closing the nutrient cycle.

Lindeman's 10% Law: Energy available to next trophic level ≈ 10% of energy at the current level

Key PointThe 10% law explains why food chains rarely exceed 4-5 trophic levels — by the fifth level, so little usable energy remains that supporting another level becomes impossible.

Major world biomes

Forest biomes — tropical rainforest (hot, wet, highest biodiversity), temperate deciduous, coniferous taiga.
Grassland biomes — tropical savanna (wet/dry seasons) and temperate grassland (steppe, prairie).
Desert & aquatic biomes — deserts (extreme aridity) and freshwater/marine ecosystems (highest primary productivity per unit area in estuaries and coral reefs).