Final answer:
Diploid organisms have two copies of each gene on homologous chromosomes, which can be either identical or different alleles.
Step-by-step explanation:
Diploid organisms generally have two copies of each gene, one inherited from each parent. These copies are located on homologous chromosomes, which are matched pairs containing the same genes in identical locations along their lengths. In cases where a single gene controls a characteristic, the diploid organism may have either identical alleles (homozygous) or different alleles (heterozygous) of that gene. This genetic combination contributes to the variation seen within a species.