Which of the following represent(s) a heterozygous condition?
Most multicellular organisms have two sets of chromosomes; that is, they are diploid. These chromosomes are referred to as homologous chromosomes. If both alleles at a gene (or locus) on the homologous chromosomes are the same, they and the organism are homozygous with respect to that gene. If the alleles for a gene are different, then organisms are heterozygous for that gene. For example, the gene for tallness can be present in three forms TT (homozygous), Tt (heterozygous), tt (homozygous).