Pearson Edexcel GCSE (9-1) Combined Science practice

Cystic fibrosis is a genetic disorder caused by a recessive allele (f). Individuals with at least one dominant allele (F) are unaffected. (a) A man and a woman are both carriers for cystic fibrosis. Using a Punnett square, determine the probability that their first child will be affected by cystic fibrosis. (b) If they have another child, what is the genotypic ratio of unaffected to affected children expected in the F1 generation from parental carriers? [4 marks]

Try the question first, then check the answer and practise the same topic again.