Q1. [3] deep thorough-understanding
In a pond ecosystem, if all the decomposers were suddenly removed, the producers and consumers might initially appear unaffected. Explain why the ecosystem would eventually collapse, referring to the role decomposers play in the cycling of matter.
Generated by claude-sonnet-4-6 · 2026-06-26 00:59 · grounding rag
Model Answer
Decomposers break down dead organic matter into simple inorganic substances (like minerals and nutrients) that are returned to the soil and used again by producers (plants).
Without decomposers, dead organisms and waste would accumulate and nutrients would not be recycled back into the soil. Producers would gradually exhaust the available inorganic nutrients and fail to grow. Since producers support all consumers, the entire food chain would collapse — leading to the breakdown of the ecosystem.
Source: Our Environment, Chapter 13, Section 13.1
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Explanation
- The key idea examiners want: nutrient/matter cycling, not energy flow.
- Three points worth 1 mark each: (1) decomposers recycle nutrients from dead matter → (2) without them, nutrients get locked in dead biomass and soil is depleted → (3) producers fail → entire food chain collapses.
- Avoid confusing energy flow (unidirectional, not recycled) with matter/nutrient cycling (recycled by decomposers). This question is specifically about cycling of matter.
- The phrase "initially appear unaffected" is addressed by noting nutrients already in soil last a while, but eventually run out — you don't need to over-explain this.