Green plants capture only about 1% of the sunlight falling on them, and only about 10% of energy at any trophic level is transferred to the next. Using both these facts, explain why a given area of wheat fields can support a larger human population when humans eat the wheat directly than when the same wheat is first consumed by deer that are then hunted for human food.
Generated by claude-sonnet-4-6 · 2026-06-26 01:00 · grounding rag
Model Answer
Green plants convert only 1% of sunlight into food energy. When humans eat wheat directly, they are at the second trophic level (producers → humans), and receive 10% of that stored energy.
When wheat is first eaten by deer, deer retain only 10% of the wheat's energy. Humans eating deer then receive only 10% of that — i.e., just 1% of the original plant energy.
Thus, direct consumption of wheat provides 10 times more energy per unit area than eating deer fed on wheat. The same wheat field can therefore sustain a far larger human population when wheat is eaten directly.
Source: Chapter 13, Section 13.1.1 — Food Chains and Webs
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Explanation
- The key idea is two successive 10% transfers vs one 10% transfer: wheat→deer→human gives 10% × 10% = 1% of plant energy to humans; wheat→human gives 10%.
- Examiners expect you to explicitly name the trophic levels involved and calculate/compare the energy available at each path.
- Mention both given facts (1% sunlight capture and 10% transfer rule) — they are separately stated in the question, so use both.
- You don't need long paragraphs; a clear comparison with the word "therefore" or "hence" signals a complete logical answer.