Final answer:
Zoe most likely inherited one faulty allele from her father, who is a carrier, and one normal allele from her mother.
Step-by-step explanation:
The most likely explanation for Zoe having cystic fibrosis is that she inherited one faulty allele from her father, who is a carrier, and one normal allele from her mother.
The mutant CFTR gene for cystic fibrosis is a recessive gene, meaning that an individual must have two copies of the mutant gene to develop the disease. If Zoe inherited one faulty allele from her father, who is a carrier, and one normal allele from her mother, she would have cystic fibrosis.
In carriers of the cystic fibrosis mutation, it has been hypothesized that there may be a heterozygote advantage, such as greater-than-normal resistance to certain infectious diseases. However, in Zoe's case, the most likely explanation is that she has inherited a faulty allele from her father and a normal allele from her mother.