# Explain how the process of meiosis contributes to genetic variation in sexually reproducing organisms, with reference to two distinct mechanisms that occur during meiosis.

> IB DP Biology Higher Level (2023 syllabus) — D3.1 Reproduction · Explain · 4 marks

## Mark scheme (4 marks)

1. Crossing over (recombination) occurs between non-sister chromatids of homologous chromosomes during prophase I
2. Crossing over produces recombinant chromatids with new combinations of alleles not present in either parental chromosome
3. Independent assortment occurs during metaphase I when bivalents align randomly at the metaphase plate
4. Independent assortment produces 2ⁿ possible combinations of chromosomes in gametes (where n = haploid number), greatly increasing genetic diversity

## Key terms

- [meiosis](https://www.gradenine.co.uk/glossary/meiosis)
- [genetic variation](https://www.gradenine.co.uk/glossary/genetic-variation)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-process-of-meiosis-b79c8cf5) · Published by Druglandscape Ltd.