What best describes multiple alleles?

The concept of multiple alleles refers to situations where more than two alternative forms of a gene exist within a population for a single trait. While an individual can only have two alleles at a locus (one inherited from each parent), the presence of multiple alleles means that the trait can exhibit a variety of phenotypes based on which combination of alleles is inherited.

For example, in the case of the ABO blood group system in humans, there are three alleles: A, B, and O. Although any individual can have at most two of these alleles, the existence of three options allows for multiple blood types (A, B, AB, and O) based on the combinations of alleles present.

This distinction is crucial in understanding genetic variability and how traits can express differently within a population, highlighting the complexity and richness of genetic inheritance beyond simple Mendelian inheritance patterns.