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A4.1.1—Evolution as change in heritable characteristics

Evolution is cumulative change in heritable characteristics of populations, driven by variation, inheritance, selection, and changing allele frequencies across generations.

Syllabus
First assessment 2025
Objective
A4.1.1
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceNovember 2023
Most common paperPaper1
Typical marks1–7

Common command terms

  • Define
  • Explain
  • Outline

Scoring notes

Common mistake
Treating evolution as a change acquired by an individual during its lifetime rather than a heritable population change.

Recent exam appearances

November 2023Paper2 ["HL"] · TZ18(a)[ 7 ]A4.1.1—Evolution as change in heritable characteristics
May 2023Paper1 ["HL"] · TZ218[ 1 ]A4.1.1—Evolution as change in heritable characteristics
Practice this objective

Coverage 2023–2023 · Updated 15 Jul 2026

Concept essentials

  • Evolution is cumulative change in heritable characteristics of a population across generations.
  • Mutation and sexual reproduction create variation on which natural selection can act.
  • Natural selection can reduce unfavourable alleles and increase advantageous inherited characteristics.
  • Acquired characteristics do not become evolutionary change unless a heritable genetic basis is passed on.
ConceptIB Biology HL