C3.2.3—Blood clotting
Blood clotting explains how a specific barrier, pathogen interaction, immune mechanism or treatment response contributes to protection against infectious disease.
- Syllabus
- First assessment 2025
- Objective
- C3.2.3
- Level
- SL
Exam analysis
Chance of appearing7%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–3
Common command terms
- Identify
- Describe
- State
- Explain
- Outline
Scoring notes
- Common mistake
- Reversing fibrinogen and fibrin in the clotting sequence.
Recent exam appearances
November 2024Paper1 ["SL"] · TZ228[ 1 ]C3.2.3—Blood clotting
May 2024Paper2 ["SL"] · TZ15(c)[ 3 ]C3.2.3—Blood clotting
May 2024Paper1 ["SL"] · TZ227[ 1 ]C3.2.3—Blood clotting
May 2023Paper1 ["SL"] · TZ228[ 1 ]C3.2.3—Blood clotting
May 2022Paper2 ["SL"] · TZ26(c)[ 7 ]C3.2.3—Blood clotting
Practice this objective
Coverage 2017–2024 · Updated 16 Jul 2026
Concept essentials
- Blood clotting has to be linked to the exact pathogen, cell, molecule or population process involved.
- The biological effect of blood clotting depends on the sequence from trigger to protective outcome.
- Clear distinctions within blood clotting prevent confusion with neighbouring immune responses.
- Evidence for blood clotting is strongest when mechanism and consequence are explained together.