Cystic fibrosis is a recessive disorder.If a couple,each of whom is heterozygous,have children,what is the probability that they will have a child with cystic fibrosis?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Question

Quizplus · Accepted Answer

When both parents are heterozygous (carriers), there is a 25% chance that their child inherits two copies of the recessive allele, thus having cystic fibrosis. This is calculated using a Punnett square, where each parent has a 50% chance of passing on the recessive allele to their offspring. The possible combinations are: 25% chance of inheriting two recessive alleles (cf cf), 50% chance of inheriting one recessive allele and one dominant allele (cf CF), and 25% chance of inheriting two dominant alleles (CF CF). Therefore, the chance of having a child with cystic fibrosis is 25%.

Cystic Fibrosis Is a Recessive Disorder