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C3.2.13—Antibiotics

Antibiotics 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
C3.2.13
Level
HL

Exam analysis

Chance of appearing6%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper2
Typical marks1–2

Common command terms

  • Explain
  • Outline
  • Identify
  • Distinguish
  • Suggest

Scoring notes

Common mistake
Explaining antibiotic action as antibody stimulation instead of inhibition of bacterial processes.

Recent exam appearances

May 2025Paper1A ["HL"] · TZ328[ 1 ]C3.2.13—Antibiotics
May 2023Paper2 ["HL"] · TZ13(b)(ii)[ 2 ]C3.2.13—Antibiotics
May 2023Paper2 ["HL"] · TZ13(b)(i)[ 1 ]C3.2.13—Antibiotics
May 2021Paper1 ["HL"] · TZ222[ 1 ]C3.2.13—Antibiotics
May 2019Paper3 ["HL"] · TZ19(a)[ 3 ]C3.2.13—Antibiotics
Practice this objective

Coverage 2016–2025 · Updated 16 Jul 2026

Concept essentials

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