What does the term "heterozygous" specifically refer to?

The term "heterozygous" specifically refers to an individual having two different alleles for a particular gene. In genetics, alleles are the different forms of a gene that can exist at a specific locus on a chromosome. When an individual possesses two different alleles—one inherited from each parent—they are described as heterozygous for that trait.

This is in contrast to being "homozygous," where an individual has two identical alleles for a gene. Heterozygosity is significant in genetics because it can affect the expression of traits, particularly when one allele is dominant over the other. For example, in a heterozygous situation where one allele is dominant and the other is recessive, the dominant allele will determine the organism's phenotype.

The concept of heterozygosity is fundamental for understanding genetic variation, inheritance patterns, and the principles of dominance and recessiveness in traits. It also plays a crucial role in areas such as natural selection and evolution, as heterozygous individuals may exhibit greater adaptability.