Science (086) — AI-generated practice question

Pesticides sprayed on crops seep into the soil and wash into the nearby pond. Microscopic organisms (phytoplankton/algae) in the pond absorb these pesticides. Small fish eat these organisms, larger fish eat the small fish, and the larger fish may be transported and consumed by humans far away.

Because pesticides are non-biodegradable, they are not broken down at each trophic level but instead accumulate in the body tissues. As each organism at a higher trophic level consumes many organisms from the level below, the pesticide concentration keeps increasing. This process is called biological magnification, which is why the concentration in the human body is far greater than in the pond water or soil.

Source: Chapter 13, Our Environment

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• Key concept to name: Biological magnification (also called biomagnification) — examiners expect this term.
• Two parts to answer: (1) the pathway through the food chain, and (2) why concentration increases (non-biodegradable + accumulates up trophic levels).
• A simple food chain — pond water/soil → producers/plankton → small fish → large fish → human — earns the pathway marks.
• The reason for higher concentration is that each organism eats many of the level below, so the chemical concentrates at each step; this must be stated explicitly.