Which term describes the genetic makeup of an organism in terms of the alleles present?

• A. Genotype
• B. Allele
• C. Phenotype
• D. Food web

Answer: (A)

Genotype describes the genetic makeup in terms of the alleles present. A gene can have different forms called alleles, and an organism typically has two copies of each gene (one from each parent). The particular combination of those two alleles—such as two dominant, two recessive, or one of each—constitutes the genotype for that gene. This is different from the phenotype, which is what the trait looks like or how it manifests, since the phenotype results from how those alleles are expressed and can be influenced by the environment. For example, with a gene for height, the genotype might be TT, Tt, or tt, while the phenotype would reflect tall or short height accordingly. An allele is simply a variant form of a gene, and a food web is unrelated to genetics.