Question

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

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.

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 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.

Answer 1

The statement that would be deemed true regarding cystic fibrosis from the options provided is:

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

This is often stated in the context of evolutionary biology, where heterozygous carriers (those with one normal allele and one cystic fibrosis allele) may have some protection against certain diseases, such as typhoid fever or possibly some forms of gastrointestinal infections.

The other statements are inaccurate because:
- Cystic fibrosis does not directly affect red blood cell production.
- Cystic fibrosis is caused by a mutation in a recessive allele, not a dominant allele replacing a recessive one.
- While cystic fibrosis is caused by a mutation in the CFTR gene, the most common mutation is a deletion of three nucleotides which removes one amino acid (phenylalanine), not just one codon.

Thus, the second response regarding carriers is the most accurate of the options listed.