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C3.2.15—Zoonoses

Zoonoses explains how a specific barrier, pathogen interaction, immune mechanism, treatment response or population process contributes to protection against infectious disease.

Syllabus
First assessment 2025
Objective
C3.2.15
Level
HL

Exam analysis

Chance of appearing1%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1B
Typical marks1

Common command terms

  • State
  • Identify
  • Explain

Scoring notes

Common mistake
Defining zoonoses as diseases from zoos rather than transfer from other animal species.

Recent exam appearances

May 2025Paper1B ["HL"] · TZ31(d)(ii)[ 1 ]C3.2.15—Zoonoses
Practice this objective

Coverage 2025–2025 · Updated 16 Jul 2026

Concept essentials

  • Zoonoses has to be linked to the exact pathogen, cell, molecule or population process involved.
  • The biological effect of zoonoses depends on the sequence from trigger to protective outcome.
  • Clear distinctions within zoonoses prevent confusion with neighbouring immune responses.
  • Evidence for zoonoses is strongest when mechanism and consequence are explained together.
ConceptIB Biology HL