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C3.2.5—Phagocytes

Phagocytes 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
C3.2.5
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceNovember 2020
Most common paperPaper1
Typical marks1

Common command terms

  • Describe
  • Outline
  • Identify

Scoring notes

Common mistake
Naming symptoms without linking them to the causative pathogen or transmission route.

Recent exam appearances

November 2020Paper1 ["HL"] · TZ022[ 1 ]C3.2.5—Phagocytes
May 2014Paper1 ["HL"] · TZ222[ 1 ]C3.2.5—Phagocytes
Practice this objective

Coverage 2014–2020 · Updated 16 Jul 2026

Concept essentials

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