# Explain why individuals with greater reproductive success are more likely to pass on their alleles to future generations, and how this leads to a change in allele frequency in a population over time.

> IB DP Biology Higher Level (2023 syllabus) — D4.1 Natural selection · Explain · 4 marks

## Mark scheme (4 marks)

1. Individuals with favourable traits/alleles survive longer or reproduce more successfully, leaving more offspring.
2. Offspring inherit alleles from parents, so favourable alleles are transmitted to the next generation at a higher rate than unfavourable alleles.
3. Over successive generations, the frequency of favourable alleles increases in the population (and unfavourable alleles decrease).
4. This cumulative change in allele frequency across generations is the mechanism of natural selection, potentially leading to adaptation of the population.

## Key terms

- [reproductive success](https://www.gradenine.co.uk/glossary/reproductive-success)
- [allele frequency](https://www.gradenine.co.uk/glossary/allele-frequency)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-individuals-with-greater-reproductive-fcd7923d) · Published by Druglandscape Ltd.