Revision Notes for Class 8 Science Chapter 12: How Nature Works in Harmony

Condensed revision notes for Class 8 Science Chapter 12: How Nature Works in Harmony – Curiosity textbook. These Class 8 Science Chapter 12 notes are ideal for quick revision just before exams.

Last Updated: September 23, 2026

• Population: all individuals of one species in an area. Community: all populations of different species interacting in an area. Ecosystem: a community plus its non-living (abiotic) environment (soil, water, air, sunlight).
• Food chain: a straight-line sequence of who-eats-whom (e.g. grass → grasshopper → frog → snake).
• Food web: the full network of overlapping, interconnected food chains in a real ecosystem — more stable than a single food chain.
• Trophic level: an organism’s position in a food chain. Producers = 1st level; herbivores = 2nd; small carnivores = 3rd; top/large carnivores = 4th (and beyond).
• Producers: make their own food (e.g. green plants, via photosynthesis). Consumers: eat other organisms (herbivores, carnivores, omnivores). Decomposers: break down dead organic matter, recycling nutrients back to producers (e.g. fungi, bacteria).
• Ecological pyramid: numbers/biomass generally decrease at each higher trophic level, since only a fraction of energy transfers up the chain (“ten percent law,” roughly).
• Removing a species at any trophic level affects both the level below (less predation) and the level above (less food) — effects ripple through the whole food web.
• Mangrove forests act as natural coastal barriers against storms/tsunamis, and provide breeding habitat for marine life and natural water filtration.
• Sustainable agriculture practices (crop rotation, organic farming, reduced chemical inputs) help maintain soil health and biodiversity long-term, compared to unsustainable monoculture with heavy fertiliser/pesticide use.

More on this chapter: NCERT Solutions for Class 8 Science Chapter 12 | Extra Questions for Class 8 Science Chapter 12 | Class 8 Science Book | Formulas/Concepts Handbook

Frequently Asked Questions

What is meant by an ecosystem, and how do living and non-living components interact within it?
An ecosystem is a community of living organisms interacting with each other and with their non-living surroundings, such as air, water, and soil, exchanging energy and matter in a balanced, interdependent system.

Why is maintaining ecological balance important?
Ecological balance ensures populations of different organisms and the resources they depend on remain stable over time, and disturbing this balance, such as through pollution or overexploitation, can disrupt entire food chains.

Written by Satish

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