C3.1.9—Pain reflex arcs
Pain reflex arcs links named stimuli, coordinating structures and effectors so body systems or plant tissues produce an integrated biological response.
- Syllabus
- First assessment 2025
- Objective
- C3.1.9
- Level
- HL
Exam analysis
Chance of appearing6%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper3
Typical marks1–3
Common command terms
- Define
- Label
- Explain
- Draw
- Identify
- Outline
- Describe
- Annotate
Scoring notes
- Common mistake
- Putting the brain before the spinal relay in a rapid pain reflex.
Recent exam appearances
November 2025Paper1A ["HL"] · TZ328[ 1 ]C3.1.9—Pain reflex arcs
November 2025Paper1A ["HL"] · TZ126[ 1 ]C3.1.9—Pain reflex arcs
May 2017Paper3 ["HL"] · TZ26(c)[ 3 ]C3.1.9—Pain reflex arcs
May 2016Paper3 ["HL"] · TZ04(c)[ 1 ]C3.1.9—Pain reflex arcs
May 2016Paper3 ["HL"] · TZ04(b)[ 2 ]C3.1.9—Pain reflex arcs
Practice this objective
Coverage 2012–2025 · Updated 16 Jul 2026
Concept essentials
- Pain reflex arcs depends on linking the stimulus to the coordinating structure or signal.
- The pathway for pain reflex arcs must keep information flow and response direction clear.
- Named tissues, hormones, neurons or effectors give pain reflex arcs its biological specificity.
- Evidence about pain reflex arcs is strongest when structure, mechanism and outcome are connected.