Cystic fibrosis is an inherited lung condition caused by a recessive allele, aaa. The dominant allele, AAA, leads to the production of normal, thin mucus. In cystic fibrosis, cells produce very thick, sticky mucus that accumulates in the airways. A father who is a carrier (heterozygous) and a mother who has cystic fibrosis (homozygous recessive) wish to have children.
State the genotypes of both parents, list the possible genotypes of their children, and determine the probability (as a percentage) that a child will inherit cystic fibrosis.
Suggest why people with cystic fibrosis have a higher frequency of bacterial lung infections.
Explain why gas exchange in the alveoli is significantly reduced in individuals suffering from cystic fibrosis.
66 exam-style questions on Edexcel IGCSE Biology Inheritance. Each one has a worked solution and a mark scheme showing where the marks go.