A man and a woman do not have CF. The man and the woman have a child who has CF. Draw a Punnett square diagram to find the probability that their next child will have CF. Use the symbols: T = dominant allele t = recessive allele Draw a ring around the genotype of any children with CF. Probability = Embryo screening for CF can be done by two methods. Method 1 • The woman becomes pregnant by sexual intercourse. • After 10 weeks of pregnancy a fine needle is inserted into the uterus. • A sample of the fluid surrounding the embryo is taken. • The DNA of the embryo is tested for CF. The screening is done free by specialist hospitals for couples who are at risk of having