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A4.1 Evolution and speciation

Evolution and speciation explain how heritable variation, molecular evidence, selection, isolation, and chromosome change produce population divergence and new species over time.

Syllabus
First assessment 2025
Topic
A4.1
Level
SL

What you’ll learn

7 learning objectives

Choose one objective for a focused lesson, or study the complete topic.

Exam analysis

An aggregate view of how the complete A4.1 Evolution and speciation appears across past papers.

Chance of appearing36%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper1

Most tested objectives

  1. A4.1.1—Evolution as change in heritable characteristics12 questions
  2. A4.1.4—Evidence from homologous structures12 questions
  3. A4.1.5—Convergent evolution11 questions

Common question formats

  • Definition or recall
  • Process explanation
  • Data analysis
  • Comparison
  • Evaluation

Exam question appearances

November 2025Paper2 ["SL"] · TZ17(a)[ 4 ]A4.1.5—Convergent evolution
November 2025Paper1A ["SL"] · TZ122[ 1 ]A4.1.7—Reproductive isolation and differential selection
May 2025Paper2 ["SL"] · TZ28(b)[ 4 ]A4.1.6—Speciation by splitting of pre-existing species
May 2025Paper2 ["SL"] · TZ33(b)[ 3 ]A4.1.7—Reproductive isolation and differential selection
May 2025Paper1A ["SL"] · TZ323[ 1 ]A4.1.5—Convergent evolution

Coverage 2010–2025 · Updated 15 Jul 2026

Study checklistA4.1 Evolution and speciation