Which best describes a heterozygote?

A heterozygote is characterized by having two different alleles for a particular gene. This genetic variability can occur in diploid organisms where one allele is inherited from each parent, resulting in different forms of a gene present at a specific locus. The presence of two different alleles can influence traits through various interactions such as dominance, co-dominance, or incomplete dominance, leading to a range of possible phenotypes.

For instance, if one allele encodes for a trait such as flower color that is dominant (let's say purple) and the other encodes for a recessive trait (like white), the heterozygote will typically exhibit the dominant characteristic (purple flowers). This is fundamental in understanding inheritance patterns and predicting trait expressions in offspring.

In contrast to the correct choice, the definition of a homozygote—individuals with identical alleles (one of the incorrect options)—does not apply here. Similarly, having no alleles indicated a lack of genetic information for that gene, which is not applicable to heterozygotes. Lastly, while having one dominant allele pertains to dominance in gene expression, it doesn’t encompass the entire definition of heterozygosity, as heterozygotes contain both dominant and recessive alleles