Question

in order for a child to develop cystic fibrosis ______.
○ a sperm carrying a cf allele must fertilize an egg that also has that allele
○ genetic recombination must occur in the father but not the mother
○ more than one sperm in the father must carry the cf allele
○ genetic recombination must occur in the mother but not the father
○ more than one egg in the mother must carry the cf allele

Explanation:

Cystic fibrosis is an autosomal - recessive disorder. For a child to have an autosomal - recessive disorder, they need to inherit two copies of the recessive allele (one from each parent). So, a sperm with the CF (recessive) allele must fertilize an egg with the CF (recessive) allele. Genetic recombination is a normal process in both parents during gamete formation and not specific to one parent for cystic fibrosis inheritance. Also, only one sperm fertilizes one egg, and having more than one sperm or egg with the allele is not relevant in the simple inheritance pattern of getting two recessive alleles (one from each gamete) for an autosomal - recessive disorder like cystic fibrosis.

Answer:

a sperm carrying a CF allele must fertilize an egg that also has that allele