What term refers to any of the alternative forms of a gene at a given locus?

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

Answer: (D)

Allele denotes any of the alternative forms of a gene at a specific locus. On homologous chromosomes, the same gene sits at the same position, yet can exist in different versions that may differ in sequence and sometimes in function. These variants explain how traits can vary between individuals, with dominance relationships shaping the observed phenotype depending on which alleles are present. The other terms describe broader genetic concepts: a chromosome is a DNA-containing structure with many genes; a genome is the full set of genetic material; a gene is the basic unit of heredity that can have different alleles but is not itself the label for the variant forms.