Generated by claude-sonnet-4-6 · 2026-06-15 06:41 · grounding rag
Model Answer
(a) Trophic level placement:
- (i) Producers → Grass
- (ii) Primary consumers → Deer / Rabbit
- (iii) Secondary consumers → Snake / Rabbit / Deer (depending on chain) → Snake (eats rabbit) or Rabbit (eats grass then eaten by snake)
- Correct food chain: Grass → Rabbit → Snake → Lion
- (i) Grass, (ii) Rabbit, (iii) Snake, (iv) Lion; Deer also at level (ii).
(b) Only 10% of energy at one trophic level is transferred to the next. A great deal of energy is lost as heat, in digestion, and in doing work. So primary consumers receive 10% of producers' energy, while secondary consumers receive only 10% of that — making primary consumers energy-richer than secondary consumers.
(c) The base is broad because producers (green plants) are present in the greatest number and possess the maximum amount of energy in the ecosystem. All other trophic levels depend on them, so they must be most abundant to support the entire food chain.
Source: Chapter 13, Section 13.1.1 – Food Chains and Webs
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Explanation
- (a) Examiners expect the correct food chain: Grass→Rabbit→Snake→Lion, with Deer also at primary consumer level.
- (b) Key phrase: 10% law — only 10% energy transfers per level; rest lost as heat/digestion/work.
- (c) Link broad base to maximum energy and numbers at producer level — both points may fetch marks.