In eukaryotic organisms, chromosomes exist as pairs. That means the genes determining an organism's heredity are duplicated although their expressions may vary. The normal condition of paired chromosomes is termed DIPLOID. When only one member of a pair is present, the condition is HAPLOID. If the alleles on a chromosome are identical, they are said to be HOMO- ZYGOUS. If they differ, they are said to be HETEROZYGOUS. Flip to the next card. Note: HAPLOID is often designated as N and DIPLOID as 2N.