Which term describes different forms of a gene that can be dominant or recessive?

• A. Dominant trait
• B. Genotype
• C. Phenotype
• D. Alleles

Answer: (D)

Genes come in different versions called alleles. These alleles can be dominant or recessive, which describes how they influence a trait when an organism has one or two copies. In a heterozygous situation, the dominant allele masks the recessive one, so the phenotype shows the trait associated with the dominant allele. If both alleles are recessive, the recessive phenotype appears. For example, the gene for flower color has alleles where one version is more likely to produce purple color, and that version will dominate over a white allele if present. The term that describes these different forms of a gene is alleles. The other terms refer to either the trait that is observed (phenotype), or to the organism’s specific gene set (genotype), rather than to the gene’s different forms themselves.