Alleles represent different variants of a gene

Now we know that these factors are called alleles and represent the different variations of a gene.Depending on which type of allele Mendel found in each seed,we can have what we call a homozygous pea,where both alleles are identical,and what we call a heterozygous pea, when the two alleles are different.This combination of alleles is known as genotype and its result, being yellow or green, is called phenotype.
To clearly visualize how alleles are distributed amongst descendants, we can a diagram called the Punnett square. You place the different alleles on both axes and then figure out the possible combinations.