Question 1
Mark has been away on holiday, and his friends Shruti and Shokoofeh took turns looking after his dog, named Jezebel. Jezebel is a female with yellow fur, and shortly after Mark returns from his holiday, it becomes obvious his dog is pregnant. She gives birth to three puppies, all of which have yellow fur.
Mark is very upset, and blames Shruti, because Shruti owns a male dog with yellow fur (named Goldie). Shokoofeh owns a male dog (named Blackie), but because he has black fur, Mark doesn’t think he can be the father.
Assume that the gene for colour of fur is located on autosomal chromosomes and ‘black’ fur colour is dominant, and ‘yellow’ fur colour is recessive. Assume there are no new mutations. Assume the genetics of dog fur colour work the same way as human hair colour. (4 marks total)
a) What is Jezebel and Goldie’s phenotype and possible genotype(s)?
(1 mark)
b) What is Blackie’s phenotype and possible genotype(s)? (1 mark)
c) What are the puppies’ phenotypes and possible genotype(s)? (1 mark)
d) Based only on the fur colour of the two possible fathers, is it certain that Goldie is the father? Explain your answer. (1 mark)
