A single variant form of a gene is called what?

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

Answer: (A)

A gene can have different versions, and each exact version is called an allele. An allele is a single variant form that can be passed from parents to offspring. An individual typically has two alleles for a gene, one on each chromosome, and those two alleles together make up the genotype. The observable trait you see, like eye color, is the phenotype, which depends on which alleles are present and sometimes on environmental factors. The other term, describing a network of feeding relationships, isn’t related to genetic variation, so it doesn’t fit here.