Explain how some harmful chemicals enter our bodies through the food chain. Why is the concentration of these harmful chemicals found to be maximum in human beings ?
Generated by claude-sonnet-4-6 · 2026-06-15 06:43 · grounding rag
Model Answer
Pesticides and other harmful chemicals used on crops are washed into water bodies. Aquatic plants and animals absorb these chemicals. Since these chemicals are non-biodegradable, they are not broken down and keep accumulating in the body of each organism.
As one organism is eaten by another, the chemicals pass from one trophic level to the next, becoming more concentrated at each step — this is called biological magnification.
Humans are at the highest trophic level, so harmful chemicals from all lower levels accumulate in their bodies, making the concentration maximum in human beings.
Source: Our Environment, Chapter 13
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Explanation
- The examiner expects you to mention: (1) entry of chemicals through water/soil into plants → animals, (2) non-biodegradable nature causing accumulation, (3) the term biological magnification, and (4) humans being at the top of the food chain = maximum concentration.
- Writing the term "biological magnification" is important — it's a key concept from this chapter and likely fetches a dedicated mark.
- Keep the chain of reasoning clear: chemicals → absorbed by plants → passed along food chain → accumulate → humans at top = highest concentration.