An organism that has two identical alleles for a trait is termed what?

An organism with two identical alleles for a trait is termed homozygous. This means that the individual carries two copies of the same allele, whether that allele is dominant or recessive. For example, if an organism has two alleles for flower color, both being the same, such as both being red (RR) or both being white (rr), it is considered homozygous for that trait.

In contrast, heterozygous refers to an organism that has two different alleles for a trait, such as having one red allele and one white allele (Rr). The terms dominant and allele refer to different concepts in genetics; a dominant allele is one that can express its trait over a recessive allele, while an allele is simply a variant form of a gene. Therefore, the distinction of homozygous is unique in identifying the scenario where an organism possesses two identical forms of a gene.