Use of pesticides to protect our crops affect organisms at various trophic levels especially human beings. Name the phenomenon involved and explain how does it happen.
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer
Phenomenon: Biological Magnification
When pesticides are sprayed on crops, they are absorbed by plants (producers). When herbivores eat these plants, the pesticides accumulate in their bodies. Carnivores eating herbivores accumulate even higher concentrations. Since these chemicals are non-biodegradable, they are not broken down and keep on concentrating at each successive trophic level.
This progressive increase in concentration of harmful chemicals at each trophic level is called biological magnification. Humans, being at the top of the food chain, accumulate the highest concentration of these pesticides, causing maximum harm.
Source: Chapter 13, Exercises (Q.6)
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Explanation
- Keyword to write: "Biological Magnification" — examiners look for this term specifically.
- The answer must mention: non-biodegradable nature of pesticides → accumulation at each trophic level → highest concentration in humans (top consumer).
- Common mistake: students explain pollution without naming the phenomenon — always name it first.
- 3 marks typically split as: 1 mark (name) + 2 marks (explanation of how it occurs through the food chain).