A child with Cystic Fibrosis has two parents who do not suffer from the disorder. Explain how this is possible and using a genetic diagram, calculate the possibility.

CF is caused by a recessive gene therefore the parents must both be carriers. As the parents do not suffer from the disorder they must be heterozygous (one normal dominant allele which masks the other recessive CF allele). The child must have received both the recessive alleles from their parents.Draw a punnet square to show that it is 25% chance the child would get CF (this must include key and titles)(4 Marks)