The term of heterozygote refers to an organism of which the cells
contain at least two different versions of the same gene in their nuclei. Each cell possesses, therefore, at least two identical chromosomes. Heterozygote organisms are carriers of genetic
characteristics of their two parents. By analyzing blood type it is possible to reveal these two gene alleles: a parent with type B who has a child with a type A produces an individual with type AB. This blood group is called heterozygous.