Topics Covered

10 key topics in this chapter

What is an Ecosystem?

Components: Biotic & Abiotic

Food Chain & Food Web

Trophic Levels

Flow of Energy (10% Rule)

Biological Magnification

Ozone Layer & Depletion

Biodegradable & Non-Biodegradable Waste

Waste Management

Human Activities & Environment

Study Resources

Formula / Reaction / Rule	Expression
10% Energy Rule	\(Energy available at level n+1 = 10% of level n\)
Food Chain	\(Producer → Primary → Secondary → Tertiary consumer\)
Ozone Depletion	\(CFC → Cl• → Cl + O₃ → ClO + O₂ (catalytic)\)
Biotic component	\(Producers (plants) + Consumers + Decomposers\)
Greenhouse Effect	\(CO₂, CH₄, N₂O trap reflected IR → temperature rise\)
Waste Management	\(Reduce → Reuse → Recycle (3R principle)\)

10% Energy Law: Only ~10% of energy is transferred from one trophic level to the next; the rest is lost as heat.

Biological magnification: concentration of persistent chemicals (e.g. DDT) increases at higher trophic levels.

Ozone layer (stratosphere) absorbs UV radiation. Chlorofluorocarbons (CFCs) catalytically destroy ozone: Cl + O₃ → ClO + O₂.

Biodegradable waste decomposes naturally (paper, vegetable peels). Non-biodegradable waste persists (plastic, metals, synthetic fibres).