cystic fibrosis is caused by a recessive allele. A child has cystic fibrosis, even though neither of his parents has cystic fibrosis. If this couple has another child, what is the probability he or she will NOT have cystic fibrosis ?

Answer 1

if both parents are normal, then they must be heterozygous for the cystic fibrosis allele. Use a Punnett Square.

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