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D3.1.2—Role of meiosis and gamete fusion

Meiosis halves chromosome number before fertilization, and gamete fusion restores diploid chromosome number while combining parental alleles in each zygote.

Syllabus
First assessment 2025
Objective
D3.1.2
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1
Typical marks1–4

Common command terms

  • Identify
  • Explain

Recent exam appearances

May 2025Paper2 ["HL"] · TZ38(a)[ 4 ]D3.1.2—Role of meiosis and gamete fusion
May 2018Paper1 ["HL"] · TZ140[ 1 ]D3.1.2—Role of meiosis and gamete fusion
Practice this objective

Coverage 2018–2025 · Updated 16 Jul 2026

Concept essentials

  • Meiosis produces haploid gametes by halving chromosome number.
  • Fertilization restores diploid chromosome number in the zygote.
  • Meiosis and gamete fusion together maintain chromosome number across generations.
ConceptIB Biology HL