Question 1
Multiple choiceMedium1 markA survey measured the mean concentrations of DDT and mercury in the tissues of consumers at trophic levels 2–5 in a lake. Which interpretation is supported by the graph?
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Answer: B. Biomagnification is an increase in pollutant concentration in consumer tissues at higher trophic levels. Both plotted concentrations rise from level 2 to level 5; at level 5, DDT is 0.8 mg kg−1 and mercury is 0.4 mg kg−1, so DDT is higher. A: recognizes the rising trends but reverses the comparison at level 5. C: follows the DDT trend but misses that mercury also increases, from 0.1 to 0.4 mg kg−1. D: recognizes both rising trends but reads the two level-5 values as equal. Remember: biomagnification is indicated by pollutant concentration increasing across higher trophic levels.