What term describes an organism with two identical alleles for a trait?

The term used to describe an organism with two identical alleles for a trait is homozygous. This condition means that both alleles at a specific gene locus are the same, whether they are dominant or recessive. For instance, if an organism has two alleles for a trait that are both dominant (like AA) or both recessive (like aa), it is considered homozygous for that trait.

This genetic uniformity can have direct implications for phenotypic expression and inheritance patterns in the organism. In contrast, heterozygous refers to having two different alleles for a trait, which can lead to a display of dominant and recessive traits depending on the dominance relationship of those alleles. Dihybrid specifically pertains to a cross between parents that differ in two traits, while codominant describes a scenario where both alleles in a heterozygote contribute equally to the phenotype, such as in blood type inheritance. Thus, recognizing homozygosity is crucial for understanding genetic traits and inheritance patterns in organisms.