A clinic screens 40 embryos for a recessive disorder. The results are shown in the table.
| Genotype | Number of embryos |
|---|---|
| $DD$ | 20 |
| $Dd$ | 12 |
| $dd$ | 8 |
The disorder occurs only in embryos with genotype $dd$. Assume the test is completely accurate.
Policy P permits any embryo predicted not to develop this disorder. Policy Q permits only embryos that cannot pass allele $d$ to their own children.
How many embryos meet each policy?
Policy P: 20 embryos; policy Q: 32 embryos.
Policy P: 32 embryos; policy Q: 12 embryos.
Policy P: 20 embryos; policy Q: 12 embryos.
Policy P: 32 embryos; policy Q: 20 embryos.
76 exam-style questions on AQA GCSE Biology 6.1 Reproduction, covering 6.1.1 Sexual and asexual reproduction, 6.1.2 Meiosis, 6.1.3 Advantages and disadvantages of sexual and asexual reproduction, 6.1.4 DNA and the genome, 6.1.5 DNA structure, 6.1.6 Genetic inheritance, 6.1.7 Inherited disorders, and 6.1.8 Sex determination. Each one has a worked solution and a mark scheme showing where the marks go.