A small pond animal can reproduce asexually or sexually. The conditions in a pond remain stable for six weeks. A new parasite then enters the pond.
Scientists collect data about the offspring produced by each method.
| Method of reproduction | Mean number of offspring produced per parent in six weeks | Offspring surviving exposure to the parasite (%) |
|---|---|---|
| Asexual | 50 | 20 |
| Sexual | 20 | 70 |
Ten parents reproduce by each method for six weeks.
Calculate the difference between the expected numbers of their offspring that survive exposure to the parasite.
Using the data and your knowledge of reproduction, suggest why this species may reproduce mainly asexually while conditions are stable, but mainly sexually after the parasite enters the pond.
186 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.