A certain chemical used as a rodenticide targets and destroys ciliated epithelial cells in the airways of rats.
Describe the function of ciliated epithelial cells in the respiratory system.
Some rats are resistant to this rodenticide. Scientists found that the resistance is due to a dominant allele, TTT.
Two heterozygous resistant rats with the genotype TtTtTt mate.
Complete the genetic diagram to find the expected ratio of resistant rats to non-resistant rats among their offspring.
| T | t | |
|---|---|---|
| T | ... | ... |
| t | ... | ... |
Ratio of resistant to non-resistant rats =
After several years of using this rodenticide, the percentage of resistant rats in the population increased.
Use Darwin’s theory of natural selection to explain this observation.
Scientists are now trialling a new rodenticide that blocks the action of mitochondria in animal cells.
Explain why this rodenticide would kill the rats.
97 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.