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D4.2.9—Biomagnification

Biomagnification raises persistent toxin concentrations at higher trophic levels because consumers ingest many contaminated organisms and cannot rapidly eliminate pollutants.

Syllabus
First assessment 2025
Objective
D4.2.9
Level
HL

Exam analysis

Chance of appearing8%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper3
Typical marks2–3

Common command terms

  • Explain
  • Define
  • State
  • Discuss
  • Identify
  • Suggest
  • Deduce
  • Outline
  • Justify

Scoring notes

Common mistake
Describing biomagnification as any pollution effect, without explaining increasing concentration at successive trophic levels.

Recent exam appearances

May 2025Paper1B ["HL"] · TZ22(a)[ 2 ]D4.2.9—Biomagnification
November 2024Paper3 ["HL"] · TZ018[ 6 ]D4.2.9—Biomagnification
May 2023Paper3 ["HL"] · TZ218(c)[ 3 ]D4.2.9—Biomagnification
May 2018Paper3 ["HL"] · TZ116(e)[ 2 ]D4.2.9—Biomagnification
May 2017Paper3 ["HL"] · TZ216(e)[ 2 ]D4.2.9—Biomagnification
Practice this objective

Coverage 2012–2025 · Updated 16 Jul 2026

Concept essentials

  • Biomagnification requires a pollutant that persists and accumulates in organism tissues.
  • Predators at higher trophic levels receive larger pollutant loads by eating many contaminated prey.
  • DDT, DDE, mercury, PCBs, and triclosan illustrate toxic effects on top consumers and humans.
ConceptIB Biology HL