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.

• 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

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