Polycystic kidney disease (PKD) is an inherited condition in Persian cats that causes fluid-filled cysts to develop in the kidneys, eventually leading to kidney failure.
The condition is caused by a dominant allele.
Explain what is meant by the term dominant allele.
Symptoms of PKD usually do not become apparent until a cat is approximately 7 years of age. Suggest why this late development of symptoms makes it difficult for breeders to reduce the number of kittens born with the condition.
A female Persian cat that is heterozygous for PKD is mated with a male cat who is also heterozygous.
Use a genetic diagram to show the genotypes of these parents, the gametes they produce, and the genotypes and phenotypes of any possible offspring.
Use the letter DDD for the dominant PKD allele and ddd for the recessive normal allele.
Explain what is meant by the term mutation.
66 exam-style questions on Edexcel IGCSE Biology Inheritance. Each one has a worked solution and a mark scheme showing where the marks go.