Explain why meiosis is important in the production of gametes in terms of chromosome number and genetic variation.

Cambridge International IGCSE Biology (0610) — 17.3 Meiosis · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Meiosis reduces the chromosome number from diploid to haploid, so that each gamete contains only one set of chromosomes.
When two gametes fuse at fertilisation, the diploid chromosome number is restored.
Meiosis also generates four genetically distinct daughter cells.
This genetic diversity of the gametes leads to variation among the offspring.

Examiner tips

Use the exact phrases "halves the chromosome number", "haploid", "genetically different", "genetic variation".
Show the sequence: meiosis → haploid gametes → fertilisation → diploid zygote.
Mention both chromosome number and genetic variation in the same answer.

Common mistakes

Confusing meiosis with mitosis or failing to state that gametes are haploid.
Omitting the link between genetic variation and the four unique gametes.
Using vague terms such as "different" without specifying "genetically different".

Mark scheme (4 marks)

Meiosis halves the chromosome number so that gametes are haploid
When two gametes fuse at fertilisation, the diploid chromosome number is restored
Meiosis produces four genetically different / unique daughter cells
This genetic difference between gametes produces genetic variation in offspring

Key terms in this question

meiosis · gametes · genetic variation