Which of the following characteristics defines a heterozygous genotype?

A heterozygous genotype is defined by the presence of two different alleles for a specific gene, typically consisting of one dominant allele and one recessive allele. This diversity in alleles allows for the expression of the dominant trait in the phenotype, while the recessive allele may not be expressed unless paired with another recessive allele. Understanding this distinction is key to grasping basic concepts of genetics, including Mendelian inheritance and how traits are passed from one generation to the next.

The other options do not accurately describe a heterozygous genotype. Identical alleles characterize a homozygous genotype, while having no alleles does not represent any form of genetic expression. A description that includes only one recessive allele does not encompass the defining feature of heterozygosity, which specifically involves the pairing of different alleles. This understanding is crucial for analyzing genetic variations and predicting potential offspring outcomes in breeding scenarios.