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D4.1.1—Natural selection as mechanism

Natural selection is the mechanism by which heritable variation leads to differential survival and reproduction in changing environments in evolving populations.

Syllabus
First assessment 2025
Objective
D4.1.1
Level
HL

Exam analysis

Chance of appearing11%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper2
Typical marks2–7

Common command terms

  • Explain
  • Identify
  • Evaluate
  • Outline
  • State
  • Describe
  • Discuss

Recent exam appearances

May 2023Paper3 ["HL"] · TZ28(b)[ 3 ]D4.1.1—Natural selection as mechanism
May 2023Paper3 ["HL"] · TZ17(d)[ 2 ]D4.1.1—Natural selection as mechanism
November 2019Paper2 ["HL"] · TZ03(b)[ 3 ]D4.1.1—Natural selection as mechanism
November 2018Paper2 ["HL"] · TZ07(c)[ 7 ]D4.1.1—Natural selection as mechanism
November 2016Paper2 ["HL"] · TZ04(b)[ 3 ]D4.1.1—Natural selection as mechanism
Practice this objective

Coverage 2013–2023 · Updated 16 Jul 2026

Concept essentials

  • Natural selection acts on individuals but changes populations across generations.
  • Advantageous traits must be heritable to increase in frequency.
  • Selection depends on environmental context and reproductive success.
ConceptIB Biology HL