What is the term for an organism that has one dominant and one recessive gene?

An organism that has one dominant and one recessive gene is referred to as heterozygous. In genetic terms, heterozygous means the individual has two different alleles for a particular gene, which includes one allele that may be dominant and the other that is recessive. This combination influences the organism's traits, or phenotype, where the dominant allele typically expresses its trait over the recessive one.

In contrast, homozygous refers to having two identical alleles for a gene, which can both be dominant or both be recessive. Genotype describes the genetic makeup of an organism—a broader term that accounts for both heterozygous and homozygous conditions. Phenotype, on the other hand, is the observable physical or biochemical characteristics of an organism, resulting from the interaction between its genotype and the environment. Thus, the term that specifically denotes having one dominant and one recessive gene is heterozygous.