Heterozygous is a genetic condition in which two different alleles are present at a particular gene locus. In other words, it is a condition in which a person has inherited different forms of a particular gene from each parent. By different forms, we generally mean that there are different portions of the gene where the sequence is different. Examples of heterozygosity: Tt, Rr, etc.

The densely coiled structure of chromatin fibres is called chromosomes. They help in the transfer of genetic materials from parents to offspring. There are two types of chromosomes, They are : Autosomes. Allosomes. The chromosomes which are responsible for determining the sex of an individual are called allosomes. They are also called hetero-chromosomes or sex chromosomes. Among 23 pairs of chromosomes, 1 pair belongs to allosomes or sex chromosomes, and the remaining 22 pairs are called autosomes.