A population of annual grass contains plants with inherited differences in root depth. Scientists grow samples from this population under two different climate conditions. No seeds or plants enter or leave the samples during the investigation.
The table shows the percentage of plants with deep roots at the start and after eight generations.
| Climate condition | Generation 0 (%) | Generation 8 (%) |
|---|---|---|
| Repeated dry periods | 50 | 86 |
| Regular rainfall | 50 | 32 |
A student concludes that alleles for deep roots will become more common in every environment.
Evaluate the student's conclusion. Explain how the results provide evidence for natural selection.
85 exam-style questions on Edexcel GCSE Biology 4.1 Evolution and natural selection, covering 4.1.1 Work of Darwin and Wallace and 4.1.2 Resistant organisms and evolution. Each one has a worked solution and a mark scheme showing where the marks go.