Schooling · Class 8 · Science · How Nature Works in Harmony · Chapter on a page
CBSE Class 8 · Science · NCERT Curiosity
How Nature Works in Harmony: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 26 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- An ecosystem is a community of…
- Producers are green plants and some…
- Consumers are organisms that cannot…
- Decomposers like fungi and bacteria…
- A food chain shows the path of…
- The carbon cycle describes how…
- The nitrogen cycle explains how…
- Formulas and facts
- Sunlight is the ultimate source of…
- Photosynthesis equation in words
- Respiration releases energy
- About 78 percent of air is nitrogen…
- At each step of a food chain, only…
- Decomposers recycle nutrients…
- A balanced ecosystem can recover…
- Watch out for
- Thinking plants only give out oxygen
- Believing nitrogen in air can be…
- Confusing a food chain with a food web
- Assuming energy increases as it…
- Thinking decomposers are unimportant…
What this chapter is about
This chapter explores how living things and their surroundings work together in a balanced way. You will learn how plants, animals, microorganisms and non-living things like air, water and soil depend on each other. Nature is not a collection of separate parts — it is a connected system where everything plays a role.
Key ideas
- An ecosystem is a community of living things (plants, animals, microorganisms) interacting with non-living things (sunlight, water, air, soil) in a particular area.
- Producers are green plants and some bacteria that make their own food using sunlight through photosynthesis; they form the base of every food chain.
- Consumers are organisms that cannot make their own food and must eat other organisms — herbivores eat plants, carnivores eat animals, omnivores eat both.
- Decomposers like fungi and bacteria break down dead plants and animals, releasing nutrients back into the soil for plants to use again.
- A food chain shows the path of energy from one organism to another; a food web shows many connected food chains in an ecosystem.
- The carbon cycle describes how carbon moves from air into plants, then into animals, and back into air through respiration and decomposition.
- The nitrogen cycle explains how nitrogen in air is fixed into soil by bacteria, taken up by plants, passed to animals, and returned to soil and air.
- Balance in nature means that the number of producers, consumers and decomposers stays roughly steady over time — until humans or disasters disturb it.
Formulas and facts to remember
- Sunlight is the ultimate source of energy for almost all life on Earth.
- Photosynthesis equation in words: carbon dioxide + water + sunlight → glucose + oxygen.
- Respiration releases energy: glucose + oxygen → carbon dioxide + water + energy.
- About 78 percent of air is nitrogen, but plants cannot use it directly; bacteria must first convert it to nitrates.
- At each step of a food chain, only about 10 percent of energy passes to the next level; the rest is lost as heat.
- Decomposers recycle nutrients; without them, dead matter would pile up and nutrients would stay locked away.
- A balanced ecosystem can recover from small disturbances, but large disturbances like deforestation may cause permanent damage.
Common mistakes
- Thinking plants only give out oxygen → Plants release oxygen during photosynthesis but also take in oxygen during respiration, especially at night.
- Believing nitrogen in air can be used directly by plants → Plants need nitrogen in the form of nitrates; bacteria must first fix atmospheric nitrogen.
- Confusing a food chain with a food web → A food chain is a single path; a food web is many chains linked together in the same ecosystem.
- Assuming energy increases as it moves up the food chain → Energy decreases at each level because most is lost as heat.
- Thinking decomposers are unimportant because they are small → Without decomposers, nutrients would never return to soil and new plants could not grow.
Quick revision
- Producers make food; consumers eat; decomposers recycle.
- Energy flows in one direction: sun → producer → consumer → lost as heat.
- Carbon and nitrogen move in cycles — they are used again and again.
- A food web is many connected food chains.
- Disturbing one part of an ecosystem can upset the whole balance.