17.3 Meiosis
- Syllabus
- 0610–2026–2027
- Topic
- 17.3
- Level
- —
Learning objectives
17.3.1Meiosis is involved in the production• State that meiosis is involved in the production of gametes17.3.2Meiosis as a reduction division• Describe meiosis as a reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells (details of the stages of meiosis are not required)
Identify meiosis as the division that produces gametes
Meiosis is involved in producing gametes for sexual reproduction. In humans, it produces sperm in the testes and eggs in the ovaries; in flowering plants, it is involved in producing the cells that lead to pollen and egg cells.
Gametes must contain one set of chromosomes so that fusion of two gamete nuclei at fertilisation restores two sets in the zygote.
Meiosis produces cells for sexual reproduction. Mitosis produces genetically identical cells for growth, repair, replacement and asexual reproduction.
Explain meiosis as reduction division
Meiosis is reduction division: a diploid cell divides to produce haploid cells whose chromosome number is half that of the parent cell. The cells produced are genetically different from one another.
For example, if a diploid parent cell has 24 chromosomes, each haploid product has 12. In humans, the change is from 46 chromosomes in a diploid cell to 23 in a gamete.
Halving the number prevents chromosome number from doubling in every generation. Genetic differences among gametes contribute to variation after fertilisation.
Reduction refers to chromosome number changing from diploid to haploid—not chromosomes becoming smaller. The detailed stages of meiosis are not required for this objective.