Which term describes the pairs of genes occupying a specific spot on a chromosome and their different forms?

Which term describes the pairs of genes occupying a specific spot on a chromosome and their different forms?

• A. Allele
• B. Locus
• C. Chromosome
• D. Gene

Answer: (A)

Alleles are the different forms of a gene that occupy the same locus on homologous chromosomes. In a diploid organism, at that spot you typically have a pair of alleles—one on each chromosome member—which can be identical or different. The phrase “their different forms” points to alleles because it’s specifically about the variants a gene can have at that location. A locus is simply the position on the chromosome, a chromosome is the structure carrying many loci, and a gene is the basic unit that can have multiple alleles; but the term that captures both the position and the variation is allele.

Alleles are the different forms of a gene that occupy the same locus on homologous chromosomes. In a diploid organism, at that spot you typically have a pair of alleles—one on each chromosome member—which can be identical or different. The phrase “their different forms” points to alleles because it’s specifically about the variants a gene can have at that location. A locus is simply the position on the chromosome, a chromosome is the structure carrying many loci, and a gene is the basic unit that can have multiple alleles; but the term that captures both the position and the variation is allele.