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D2.1.4—Roles of mitosis and meiosis

Mitosis maintains chromosome number for growth and repair, while meiosis halves chromosome number to form genetically varied gametes for reproduction.

Syllabus
First assessment 2025
Objective
D2.1.4
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper2
Typical marks1–7

Common command terms

  • State
  • Distinguish
  • Describe
  • Explain
  • Outline

Scoring notes

Common mistake
Failing to state both sides of a mitosis-versus-meiosis comparison.

Recent exam appearances

May 2025Paper2 ["HL"] · TZ19(b)[ 4 ]D2.1.4—Roles of mitosis and meiosis
May 2025Paper2 ["HL"] · TZ38(b)[ 7 ]D2.1.4—Roles of mitosis and meiosis
May 2024Paper2 ["HL"] · TZ24(b)(ii)[ 3 ]D2.1.4—Roles of mitosis and meiosis
May 2021Paper1 ["HL"] · TZ112[ 1 ]D2.1.4—Roles of mitosis and meiosis
Practice this objective

Coverage 2021–2025 · Updated 16 Jul 2026

Mitosis Preserves Cells; Meiosis Makes Gametes

Eukaryotic cells use mitosis to maintain chromosome number and genome, whereas meiosis halves chromosome number and generates genetic diversity.

Nuclear division must occur before cell division so each daughter receives a nucleus rather than becoming an anucleate cell.

Feature Mitosis Meiosis
Main roles Growth, repair, replacement, asexual reproduction Production of cells for sexual reproduction
Nuclear divisions One Two
Chromosome number Maintained Halved
Genetic outcome Genome normally maintained New allele combinations generated

Meiosis is not simply mitosis twice: homologous chromosomes pair and separate in its first division, creating the reduction in chromosome number.

Roles of mitosis and meiosis

Assessment in practice

1–4 marks
How it is assessed

This objective is assessed through structured response, commonly using State / Distinguish / Describe.

Command terms

State / Distinguish / Describe / Explain / Outline

What earns marks

Build the answer around this relationship: Mitosis produces two genetically identical daughter nuclei or cells.

Watch for

Failing to state both sides of a mitosis-versus-meiosis comparison.

Representative question

Question 1

[Maximum number: 5]

Distinguish between the processes of meiosis and mitosis.

Core Cell Division

  • Cell division produces daughter cells for growth, repair or reproduction; cytokinesis divides cytoplasm by a contractile ring in animals or a cell plate in plants.
  • DNA replication creates sister chromatids joined at centromeres before nuclear division.
  • Mitosis preserves chromosome number: chromosomes condense, align, sister chromatids separate and nuclei reform, producing genetically identical nuclei.
  • Meiosis follows one replication with two divisions: homologous chromosomes separate in meiosis I and sister chromatids in meiosis II, producing haploid cells.
  • Crossing over, independent orientation and random fertilization generate allele combinations.
  • Non-disjunction is failed chromosome separation and can produce aneuploid cells, including trisomy 21.
  • Identify stages in micrographs from chromosome condensation, equatorial alignment, separation and nuclear-envelope cues.

Concept essentials

  • Mitosis produces two genetically identical daughter nuclei or cells.
  • Meiosis produces haploid cells for sexual reproduction.
  • Mitosis supports growth, repair and asexual reproduction.
  • Meiosis prevents chromosome doubling after fertilization and contributes to variation.