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D4.1.12 (HL)—Types of selection

Directional, stabilizing and disruptive selection differ in which phenotypes are favoured and how variation changes in evolving populations in evolving populations.

Syllabus
First assessment 2025
Objective
D4.1.12
Level
HL

Exam analysis

Chance of appearing10%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper1
Typical marks1

Common command terms

  • Explain
  • Identify

Recent exam appearances

November 2025Paper1A ["HL"] · TZ138[ 1 ]D4.1.12 (HL)—Types of selection
May 2025Paper1B ["HL"] · TZ14(c)[ 2 ]D4.1.12 (HL)—Types of selection
May 2023Paper1 ["HL"] · TZ135[ 1 ]D4.1.12 (HL)—Types of selection
May 2022Paper1 ["HL"] · TZ236[ 1 ]D4.1.12 (HL)—Types of selection
November 2021Paper1 ["HL"] · TZ036[ 1 ]D4.1.12 (HL)—Types of selection
Practice this objective

Coverage 2016–2025 · Updated 16 Jul 2026

Concept essentials

  • Directional selection shifts the population toward one extreme.
  • Stabilizing selection favours intermediate phenotypes.
  • Disruptive selection favours both extremes over intermediate forms.
ConceptIB Biology HL