What Happens to Waste in Nature? (12.6) — "How Nature Works in Harmony"

1. 13 marks

   Define decomposition and decomposers/saprotrophs, including the meaning of the word's roots.

   Hint. The word combines a root meaning 'rotten' with 'troph' meaning food, same pattern as autotroph/heterotroph.

   ✦ Microorganisms like fungi and bacteria break down complex substances in dead plants and animals into simpler ones, returning important nutrients to the soil — this process is called decomposition, which is why the organisms carrying it out are called decomposers or saprotrophs (sapro = rotten + troph = food).

2. 22 marks

   Besides fungi like mushrooms, what other organisms does the chapter name as helping break down waste, and what specific example does it give?

   Hint. The chapter names small insects working on a very specific kind of waste.

   ✦ Tiny insects such as beetles and flies, which the chapter says can be found 'on animal droppings — like elephant dung — as they help break it down and recycle nutrients, back into the environment.'

3. 33 marks

   Explain why the chapter states 'in nature, nothing is wasted — everything is reused,' connecting this directly to decomposers' role.

   Hint. Trace where the nutrients in dead matter actually end up, according to the chapter.

   ✦ Decomposers break down dead plants, animals and waste into simpler substances and return important nutrients to the soil; since plants then grow using nutrients that come from this very decomposition process, the material from dead organisms doesn't disappear — it re-enters the ecosystem as nutrients for new growth, which is exactly why the chapter can say decomposers 'play an important role in recycling nutrients' and nothing in nature truly goes to waste.

4. 43 marks

   Ever heard of... how do migratory birds like the Demoiselle Crane benefit an ecosystem beyond simply visiting it?

   Hint. The chapter lists several distinct roles these birds play along their migration route.

   ✦ Migratory birds like the Demoiselle Crane (which visits Khichan village, Jodhpur district, in winter) act as pollinators and seed dispersers along their migration path, linking two separate habitats together; they also prey on insect pests, indirectly helping farmers control pest populations and supporting healthy crop growth — which is why they matter beyond simply enhancing the aesthetics of the habitats they visit.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 12 (hecu112.pdf), Reprint 2026-27, pages 190-209. Questions are referenced from the NCERT textbook for identification.