Question

this passage describes the antenna type trait in fruit flies:
most fruit flies have a pair of antennae on their head. but, some flies appear to have an extra pair of legs on their head instead! these flies have a mutation, or change, in a gene that affects body development. this mutation makes the cells in the flys head form mutated antennae that are like legs.
in a group of fruit flies, some individuals have mutated antennae and others have normal antennae. in this group, the gene for the antenna type trait has two alleles. the allele a is for mutated antennae, and the allele a is for normal antennae.
a certain fruit fly from this group has normal antennae. this fly has two alleles for normal antennae.
based on this information, click the blue words to correct any errors in the text.
this fruit flys genotype for the antenna type trait is normal antennae.
this fruit flys phenotype for the antenna type gene is aa.
this fruit fly is homozygous for the antenna type gene.

Explanation:

1. Genotype refers to the genetic makeup (the alleles an organism carries), while phenotype is the observable trait. The fly has two alleles for normal antennae, so its genotype is aa, not "normal antennae".
2. Phenotype is the physical observable trait, so this fly's phenotype is "normal antennae", not aa.
3. Homozygous means having two identical alleles for a gene. Since the fly has two a alleles (both for normal antennae, identical), this statement is correct.

Answer:

Corrected text:
This fruit fly's genotype for the antenna type trait is aa.
This fruit fly's phenotype for the antenna type gene is normal antennae.
This fruit fly is homozygous for the antenna type gene.