1.) Either of a pair of alternative characteristics, such as smooth and wrinkled seed.
2.) One of a group of genes that occur alternatively at a given locus.
Most multicellular plants have diploid (two) sets of chromosomes. These chromosomes are referred to as homologous chromosomes. Diploid plants have one copy of each gene (and therefore one allele) on each chromosome. If both alleles are the same, they are homozygotes. If the alleles are different, they are heterozygotes.
