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C2.2.6—Neurotransmitter release

Neurotransmitter release occurs when presynaptic depolarization opens calcium channels and calcium triggers vesicle fusion with the presynaptic membrane, linking cellular mechanisms to rapid communication in nervous systems.

Syllabus
First assessment 2025
Objective
C2.2.6
Level
SL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper2
Typical marks1–3

Common command terms

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Recent exam appearances

November 2025Paper2 ["SL"] · TZ15(a)[ 1 ]C2.2.6—Neurotransmitter release
May 2025Paper2 ["SL"] · TZ13(c)[ 3 ]C2.2.6—Neurotransmitter release
November 2022Paper2 ["SL"] · TZ05(b)[ 2 ]C2.2.6—Neurotransmitter release
November 2020Paper2 ["SL"] · TZ03(b)(ii)[ 3 ]C2.2.6—Neurotransmitter release
May 2017Paper1 ["SL"] · TZ125[ 1 ]C2.2.6—Neurotransmitter release
Practice this objective

Coverage 2017–2025 · Updated 15 Jul 2026

Concept essentials

  • An arriving action potential depolarizes the presynaptic terminal.
  • Calcium ions enter the presynaptic neuron through calcium channels.
  • Calcium triggers vesicle fusion with the presynaptic membrane.
  • Neurotransmitters are released into the synaptic cleft by exocytosis.
ConceptIB Biology SL