A farmer kept two groups of healthy pigs in separate buildings. The pigs in group A were given the same antibiotic each day for 6 weeks. The pigs in group B were not given an antibiotic.
Scientists measured the percentage of bacteria in the pigs that were resistant to the antibiotic.
| Week | Resistant bacteria in group A (%) | Resistant bacteria in group B (%) |
|---|---|---|
| 0 | 1 | 1 |
| 3 | 19 | 2 |
| 6 | 67 | 3 |
Use the results to explain how antibiotic resistance evolved by natural selection in group A.
71 exam-style questions on AQA GCSE Biology 6.3 The development of understanding of genetics and evolution, covering 6.3.1 Theory of evolution, 6.3.2 Speciation, 6.3.3 The understanding of genetics, 6.3.4 Evidence for evolution, 6.3.5 Fossils, 6.3.6 Extinction, and 6.3.7 Resistant bacteria. Each one has a worked solution and a mark scheme showing where the marks go.