Which genotype describes having identical alleles for a trait?

• A. Heterozygous
• B. Phenotype
• C. Inheritance
• D. Homozygous

Answer: (D)

Having two identical alleles for a gene means the genotype is homozygous. This describes the allele composition at a specific gene, with examples like AA or aa. When the two alleles are the same, the organism is homozygous for that trait, regardless of whether the trait is dominant or recessive. In contrast, a genotype with two different alleles (such as Aa) is heterozygous. The phenotype—the observable trait—can be influenced by which allele is dominant, but the question focuses on the genotype itself. So the term that fits “identical alleles for a trait” is homozygous. For reference, two identical alleles can produce a recessive phenotype (aa) or a dominant phenotype (AA), whereas a mix of alleles (Aa) is heterozygous.