What term refers to an organism with two identical alleles for a particular trait?

The term that refers to an organism with two identical alleles for a particular trait is "homozygous." When an organism has two identical alleles, whether they are for a dominant or recessive trait, it is said to be homozygous for that gene. This means that both alleles contribute the same genetic information for the characteristic being observed, resulting in a uniform expression of that trait.

For example, if an organism has two alleles for a certain flower color gene, both being red (RR) or both being white (rr), it is homozygous for that trait. Homozygous conditions can lead to predictable patterns of inheritance, aligning with Mendelian genetics.

In contrast, heterozygous refers to having two different alleles for a trait, which may lead to different expressions. Monohybrid specifically addresses a genetic cross between individuals differing in one trait, while phenotype pertains to the observable characteristics of an organism, including but not limited to traits governed by alleles. Understanding these terms is essential in genetics, as they provide a foundation for studying inheritance patterns and traits.