Outline why meiosis, rather than mitosis, is used to produce gametes.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Meiosis reduces the chromosome number by half, so that when two gametes fuse at fertilisation the correct diploid chromosome number is restored.
Meiosis produces four daughter cells (gametes) instead of two.
The daughter cells are genetically different from each other, providing genetic variation.
Meiosis produces four daughter cells (gametes) instead of two.
The daughter cells are genetically different from each other, providing genetic variation.
Examiner tips
- Use the exact phrases from the mark scheme – ‘halves the chromosome number’, ‘four daughter cells’, ‘genetically different’. Show the logical sequence: reduction of chromosome number → fertilisation restores diploid → four gametes → variation.
Common mistakes
- Confusing mitosis with meiosis; writing that mitosis also halves chromosome number. Omitting the point about genetic variation or the number of gametes produced.
Mark scheme (4 marks)
- Meiosis halves the chromosome number
- So that when two gametes fuse at fertilisation the correct diploid chromosome number is restored
- Meiosis produces four daughter cells / gametes
- The daughter cells are genetically different from each other, producing genetic variation
Key terms in this question
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Outline" question →
- Decode the mark scheme abbreviations →
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