Biological Magnification
Biological magnification is the gradual increase in the concentration of harmful, non-biodegradable substances at higher trophic levels in a food chain.
Practice This ConceptMain explanation
Teacher explanation
When a toxic substance like DDT enters an ecosystem, it may not break down easily. Small organisms absorb it in small amounts, and larger organisms eat many smaller ones, so the concentration increases at each step. The top consumer therefore receives the highest concentration.
Example
In a water body, tiny plankton may have a little pesticide, small fish may have more, bigger fish may have still more, and birds that eat fish may receive the highest amount.
Simple analogy
More eating up the chain means more toxin up the chain.
Common confusion
Students often think the toxin amount stays the same at every level. The correct idea is that concentration increases as we move up the food chain.
Exam tip
In answers, write the words non-biodegradable and higher trophic levels to show full understanding.
Answer writing and exam use
1-mark use
Write the exact meaning of biological magnification in one clean line.
2-mark use
Define biological magnification and add one example or condition.
3-mark use
Explain biological magnification, show the method or example, and mention the common mistake.
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