How is a heterozygous organism defined?

A heterozygous organism is defined as having two different alleles for a specific trait. This means that for a given gene, one allele is inherited from one parent, and a different allele is inherited from the other parent. The presence of different alleles can lead to variation in the expression of traits, often resulting in a dominant trait being expressed if one allele is dominant over the other. In contrast, if an organism were to have only one allele for a trait, it would be described as homozygous, which does not characterize heterozygosity. Additionally, if both alleles were the same, that would also indicate a homozygous condition rather than heterozygous. It is also important to note that while the concept of a recessive trait is relevant in discussions of alleles, it does not define heterozygosity itself; rather, recessive traits usually require two copies of the recessive allele to be expressed. Thus, the distinction of having different alleles for a trait is crucial to understanding what it means to be heterozygous.