Biology

Mendel referred to the "factors" that determine a plant's phenotype as discrete units that govern traits.

Modern genetics identifies these as alleles, which are different forms of the same gene.

For a given trait, an organism inherits two alleles, one from each parent. These alleles can be dominant or recessive.

A dominant allele determines the phenotype when present, while a recessive allele is only expressed when both inherited alleles are recessive.