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A2.1.5—Spontaneous formation of vesicles

Amphipathic molecules can self-assemble into vesicles that concentrate reactants and maintain internal chemistry, providing a plausible compartment before fully living cells evolved.

Syllabus
First assessment 2025
Objective
A2.1.5
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceMay 2022
Most common paperPaper1
Typical marks1

Common command terms

  • State
  • Identify

Scoring notes

Common mistake
Treating protobionts as complete modern cells with nuclei and organelles.

Recent exam appearances

May 2022Paper1 ["HL"] · TZ13[ 1 ]A2.1.5—Spontaneous formation of vesicles
May 2015Paper3 ["HL"] · TZ12(a)[ 1 ]A2.1.5—Spontaneous formation of vesicles
Practice this objective

Coverage 2015–2022 · Updated 15 Jul 2026

Concept essentials

  • Amphipathic molecules can self-assemble in water.
  • Closed vesicles create an internal environment distinct from the surroundings.
  • Compartmentalization can concentrate reactants and retain useful polymers.
  • A membrane boundary plausibly preceded complex cellular organelles.
ConceptIB Biology HL