Question

this passage describes the cystic fibrosis trait in humans:
cystic fibrosis is a condition that affects mucus. mucus is a jelly - like substance that certain cells produce to protect the body from infection. humans with cystic fibrosis produce mucus that is thicker and stickier than usual. this sticky mucus builds up in the lungs and interferes with breathing.
in a group of humans, some individuals have cystic fibrosis and others do not. in this group, the gene for the cystic fibrosis trait has two alleles. the allele f is for not having cystic fibrosis, and the allele f is for having cystic fibrosis.
charlie is a human from this group. charlies phenotype for the cystic fibrosis trait is having cystic fibrosis. charlies genotype for the cystic fibrosis gene is ff.
based on this information, complete the following statement.
charlie is ______ for the cystic fibrosis gene.
options: heterozygous, homozygous

Explanation:

To determine Charlie's genotype classification, we recall: Homozygous means having two identical alleles for a gene (e.g., \( ff \) or \( FF \)), while heterozygous means having two different alleles (e.g., \( Ff \)). Charlie's genotype is \( ff \), so both alleles are the same. Thus, he is homozygous.

Answer:

homozygous