Introduction to Environment and Ecology

Environment basics

The environment is everything around us — air, water, soil, plants, animals and humans — and the way they interact. Ecology is the study of these interactions.

Ecosystem

• Biotic components: living things — producers, consumers, decomposers
• Abiotic components: non-living things — sunlight, air, water, soil, temperature
• Producers (green plants) make food by photosynthesis.
• Consumers: herbivores (primary), carnivores (secondary/tertiary), omnivores
• Decomposers (bacteria, fungi) break down dead matter and return nutrients to the soil.

Food chain and energy flow

Grass → Grasshopper → Frog → Snake → Eagle. Energy flows in one direction; only about 10% of energy passes to the next level (10% law).

Atmosphere and ozone

• Layers: Troposphere → Stratosphere → Mesosphere → Thermosphere → Exosphere
• The ozone layer (in the stratosphere) absorbs harmful UV rays; CFCs damage it.
• Greenhouse gases: CO₂, methane (CH₄), nitrous oxide (N₂O), water vapour — they cause global warming.

Pollution and key terms

• Air pollution (smoke, PM2.5), water pollution (sewage, chemicals), soil and noise pollution
• Biodegradable waste decomposes naturally; non-biodegradable (plastic, glass) does not.
• Biodiversity = variety of life; hotspots in India include the Western Ghats and Himalayas.

Important days

• World Environment Day – 5 June; Earth Day – 22 April; Ozone Day – 16 September

Exam tips (RRB NTPC)

• Remember examples for each level of a food chain.
• Link gases to their effects (CO₂ → warming, CFCs → ozone depletion).

Analogy

Think of an ecosystem as a railway network. The sun is the power station — it supplies all the energy. Green plants are the engines that convert that power into food (producers). Passengers who board at each station are the consumers: herbivores get on first, then carnivores who "feed" on them.

At every station some energy is lost — like fuel burned between stations — so only about 10% reaches the next level. Decomposers are the cleaning and maintenance crew: they recycle what is left so the network keeps running. And the ozone layer is the roof of the station, shielding everyone from the harsh UV "rain".