Question

Which statement about cystic fibrosis is true?(1 point)
Responses

Cystic fibrosis is caused by a mutation in which a dominant allele replaces a recessive allele.
Cystic fibrosis is caused by a mutation in which a dominant allele replaces a recessive allele.

Cystic fibrosis is caused by a deletion of one codon in the DNA molecule.
Cystic fibrosis is caused by a deletion of one codon in the DNA molecule.

Carriers have an advantage over people who do not have the cystic fibrosis mutation.
Carriers have an advantage over people who do not have the cystic fibrosis mutation.

Cystic fibrosis affects a person’s ability to make normal red blood cells.
Cystic fibrosis affects a person’s ability to make normal red blood cells.

Answer 1

"Cystic fibrosis is caused by a deletion of one codon in the DNA molecule." — True.

Explanation: The most common CF mutation (ΔF508) is a three-nucleotide (one codon) deletion that removes a phenylalanine residue from the CFTR protein. CF is an autosomal recessive disease (not caused by a dominant allele), carriers do not have a clearly established selective advantage, and the disease does not affect red blood cell formation.