What is the term for an individual who has one dominant and one recessive gene for a trait?

The term that describes an individual with one dominant and one recessive gene for a trait is "heterozygous." This term is used in genetics to indicate the presence of two different alleles at a gene locus. In this case, one allele is dominant, meaning it can mask the expression of the other allele, which is recessive. Consequently, the organism carries both forms of the gene, which can be significant in determining its traits, particularly if the dominant allele influences the phenotype.

Understanding this term is crucial because it helps to differentiate between various genetic combinations, specifically homozygous (where both alleles are the same) and heterozygous (where they are different). Other options such as hybrid are often used interchangeably with heterozygous, but they may also carry additional meanings depending on the context. Phenotype refers to the observable traits, while genotype signifies the genetic makeup itself, hence focusing on the specific combination of alleles present.