The dominant allele for the ability to smell the scent of a particular flower is represented by A. The recessive allele, which does not allow a person to smell the scent of the flower, is represented by a.

1. (a)(i)Using these letters, indicate each of the following: the genotype of a woman who is unable to smell the flower[1]
2. (a)(ii)the possible alleles found in the gametes of a woman who can smell the flower. ................................................ and ................................................ [2]
3. (b)Fig. 4.1 represents some alleles on part of the sex chromosomes of a woman and of a man. In the space below, draw these alleles as they might appear in a sperm cell that carries the Y chromosome.[2]
4. (c)Fig. 4.2 shows how the alleles on one of the chromosomes might appear in a cell taken from somewhere else in the man's body. Allele B shows a mutation. Suggest two possible causes of the mutation.[2]
5. (d)Mutated alleles such as that shown in Fig. 4.2 are usually recessive. Use your knowledge of genetics to explain why society discourages marriage between closely-related people.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.