An alternative form of a gene located at a specific position on a chromosome is called what?

• A. Trait
• B. Allele
• C. Gene
• D. Genome

Answer: (B)

Variation at a specific gene locus is described by alleles. An allele is a variant form of a gene that occupies the same position on homologous chromosomes. Different alleles can lead to different versions of a trait, which is why we think in terms of allelic variation rather than a single, fixed gene. A trait is the observable characteristic, often influenced by multiple genes and the environment. A gene is the basic unit of heredity, the sequence that can vary in form, while a genome is the entire set of genetic material. In diploid organisms, you typically have two alleles for each gene, one on each chromosome of the pair.