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IB Biology HL D4.2.9 Biomagnification Questions

Analyse pollutant concentration across trophic levels and evaluate DDT control benefits against persistent ecological and health risks.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Interpret trophic-level data to identify bioaccumulation and the greatest DDT or mercury exposure in top predators.
  • Explain biomagnification of persistent, fat-soluble pollutants such as DDT, mercury or plastics through marine and terrestrial food chains.
  • Evaluate DDT vector-control benefits against biomagnification, persistence and ecological or public-health risks.

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Study D4.2.9—Biomagnification conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL D4.2.9 Biomagnification Questions question 1

[Maximum number: 2]

The diagram shows levels of DDT, a pesticide, in an aquatic food web in Lake Kariba, Africa. Numbers represent ppm (parts per million) of DDT in fat tissue.

Figure for Question IB Biology HL D4.2.9 Biomagnification Questions question 1 — IB Biology HL

Justify the observation that the crocodile has a higher mean DDT level than the cormorant or tigerfish.

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