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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
HL

What you’ll learn

11 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 paperPaper2

Most tested objectives

  1. A4.1.11 (HL)—Abrupt speciation in plants10 questions
  2. A4.1.4—Evidence from homologous structures8 questions
  3. A4.1.6—Speciation by splitting of pre-existing species7 questions

Common question formats

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

Exam question appearances

November 2025Paper1A ["HL"] · TZ333[ 1 ]A4.1.5—Convergent evolution
May 2025Paper2 ["HL"] · TZ29(a)[ 4 ]A4.1.4—Evidence from homologous structures
May 2025Paper2 ["HL"] · TZ38(c)[ 4 ]A4.1.11 (HL)—Abrupt speciation in plants
May 2025Paper1A ["HL"] · TZ221[ 1 ]A4.1.6—Speciation by splitting of pre-existing species
November 2024Paper2 ["HL"] · TZ07(b)[ 4 ]A4.1.2—Evidence from sequences
Practice this topic

11 original exam-style questions based on the patterns above.

Coverage 2012–2025 · Updated 15 Jul 2026

Study checklistA4.1 Evolution and speciation