When two alleles are homozygous, how do the traits compare?

• A. They are different.
• B. They are identical.
• C. They are incomplete.
• D. They are dominant.

Answer: (B)

When two alleles are homozygous, it means that both alleles for a particular gene are the same, either both dominant or both recessive. This uniformity results in traits that are identical, as there is no variation between the alleles contributing to the phenotypic expression. In contrast, if the alleles were different, the organism would be heterozygous, which could lead to different trait outcomes depending on which allele is dominant. The idea of incomplete traits refers to situations where neither allele is completely dominant over the other, resulting in a blending of traits, further highlighting how homozygous alleles are distinctly not incomplete. The concept of dominance pertains to the interaction of alleles in heterozygous situations rather than homozygous ones, where the outcome is solely based on the identical alleles present.