Q BankQuestion BankDocsDocuments

C3.2.1—Pathogens cause infectious diseases

Pathogens cause infectious diseases explains how a specific barrier, pathogen interaction, immune mechanism or treatment response contributes to protection against infectious disease.

Syllabus
First assessment 2025
Objective
C3.2.1
Level
SL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2024
Most common paperPaper3
Typical marks1–3

Common command terms

  • Describe
  • Distinguish
  • Outline
  • Define
  • State
  • Explain

Scoring notes

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

Recent exam appearances

May 2024Paper3 ["SL"] · TZ117(b)[ 1 ]C3.2.1—Pathogens cause infectious diseases
May 2024Paper3 ["SL"] · TZ117(a)[ 3 ]C3.2.1—Pathogens cause infectious diseases
May 2024Paper3 ["SL"] · TZ216(a)[ 1 ]C3.2.1—Pathogens cause infectious diseases
May 2023Paper3 ["SL"] · TZ118(c)[ 3 ]C3.2.1—Pathogens cause infectious diseases
May 2023Paper3 ["SL"] · TZ217(b)[ 3 ]C3.2.1—Pathogens cause infectious diseases
Practice this objective

Coverage 2014–2024 · Updated 16 Jul 2026

Concept essentials

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