Describe the role of meiosis in sexual reproduction, including how it contributes to genetic variation in offspring.

AQA GCSE Biology (8461) — 4.6.1 Reproduction · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Meiosis produces gametes (sex cells) that contain half the usual number of chromosomes (haploid, 23 chromosomes in humans). During meiosis chromosomes are shuffled and genes are mixed, producing non‑identical gametes. When fertilisation occurs, the male and female gametes fuse, restoring the full chromosome number and creating a new combination of alleles in the offspring.

Examiner tips

Use the word "meiosis" and "gametes"; mention haploid 23 chromosomes; explain shuffling/mixing of genes; state fertilisation restores diploid number and new allele combinations.
Show the logical sequence: meiosis → haploid gametes → shuffling → fertilisation → diploid offspring with new allele mix.

Common mistakes

Confusing mitosis with meiosis; not stating haploid number; omitting the role of fertilisation; using vague terms like "different" instead of "non‑identical".

Mark scheme (4 marks)

Meiosis produces gametes (sex cells / sperm and egg cells)
Gametes contain half the usual number of chromosomes (haploid / 23 chromosomes)
During meiosis, chromosomes are shuffled / genes are mixed, producing non-identical cells
Fertilisation (fusion of male and female gametes) restores the full chromosome number, producing a new combination of alleles in the offspring

Key terms in this question

meiosis