A closed laboratory population of beetles reproduces sexually. No beetles are added to the population. Scientists sequence the same region of one gene in every beetle in three generations.
| Generation | Alleles detected and their DNA base sequences |
|---|---|
| 1 | A1: ACGTTA; A2: ACGCTA |
| 6 | A1: ACGTTA; A2: ACGCTA; A3: ACGTAA |
| 7 | A1: ACGTTA; A2: ACGCTA; A3: ACGTAA |
Use the data to explain how allele A3 could have appeared in generation 6 and then been inherited by beetles in generation 7.
122 exam-style questions on OCR GCSE Biology 5.2 Natural selection and evolution, covering 5.2.1 Genetic variation within a population, 5.2.2 Developments in classification systems, 5.2.3 How evolution occurs through natural selection, 5.2.4 Evolution as change over time, 5.2.5 Evidence for evolution, and 5.2.6 Darwin and Wallace. Each one has a worked solution and a mark scheme showing where the marks go.