The presence of identical alleles on homologous chromosomes.
in an individual, no variation in alleles at a locus
Presence of two identical alleles at a locus in a diploid organism (see heterozygosity). It is the result of inheritance of identical alleles from both parents. horn - In armoured cells an extension of the apical or antapical plates. House-keeping genes: Genes which are constitutively expressed in most cells because they provide basic functions.