What does the term "homozygous" refer to?

The term "homozygous" specifically refers to an organism that possesses two identical alleles for a particular trait. This means that both copies of the gene, one inherited from each parent, are the same. For instance, if a trait is determined by a gene where one allele codes for a dominant purple flower color and another for a recessive white color, an organism is homozygous if it has either two purple alleles (homozygous dominant) or two white alleles (homozygous recessive).

This concept is essential in Mendelian genetics as it helps to predict the inheritance patterns of traits in offspring. The fact that the organism has identical alleles often results in a consistent expression of that trait, either displaying the dominant trait or the recessive trait consistently.

In contrast, having one allele for a trait denotes a heterozygous condition, possessing multiple alleles includes variations that may exist for a single trait across a population, and having different traits does not pertain to allele similarity and heterozygosity.