A population of rabbits lives on an island. There is inherited variation in how efficiently individual rabbits use grass as food. Rabbits with efficient food use need less grass than rabbits with less efficient food use for the same amount of growth.
During a dry summer, grass was scarce. Scientists followed two groups of rabbits and recorded the results.
| Inherited characteristic | Number at the start of the summer | Number alive at the end of the summer | Number of offspring produced by the survivors |
|---|---|---|---|
| efficient food use | 50 | 40 | 80 |
| less efficient food use | 50 | 20 | 20 |
Calculate the number of rabbits with efficient food use that were not alive at the end of the summer.
State which group of rabbits produced more offspring.
Use the information to explain how the proportion of rabbits with efficient food use could change over several generations.
The following summer, grass is plentiful. Suggest how the selection pressure on the two groups of rabbits might differ from that in the dry summer.
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.