Meiosis
- ICSE Class 10, Unit 1 Basic Biology
Meiosis is the cell division that makes gametes, the egg and sperm, and halves the chromosome number so each gamete gets one of every pair.
The ICSE syllabus calls meiosis a reduction division. It does not ask for its stages. What matters is the result.
A body cell holds its chromosomes in pairs. The two chromosomes of a pair are called homologous chromosomes. This full set is diploid. Meiosis makes cells with just one chromosome from each pair. This half set is haploid. When a sperm and an egg join, the full number comes back.
- Mitosis: in body cells. Two new cells, with the same number of chromosomes.
- Meiosis: in the cells that form gametes. Four new cells, each with half the number.
A small example
Human body cells have 46 chromosomes. Each sperm and each egg has 23. At fertilisation, 23 + 23 = 46.
Where marks go
The 2024 ICSE Biology paper said a male gorilla has 48 chromosomes in each body cell. It asked how many each sperm has. The answer was 24. CISCE's report on the 2024 ICSE Biology paper names confusion about "the number of chromosomes in body cells and gametes". Halve the body-cell number for a gamete. Keep it the same for a cell made by mitosis.
The ICSE 2027 specimen paper asks for the type of cell division that forms gametes in humans. Its answer is meiosis.
Sources
Facts last checked against these sources on 30 September 2026.
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