Which term describes alternative forms of the same gene?

• A. Allele
• B. Autosome
• C. Carrier
• D. Chromosome

Answer: (A)

Alternate forms of the same gene are called alleles. A gene sits at a specific location on a chromosome, and variations in the DNA sequence at that spot create different versions of the gene. In diploid organisms, you have two alleles for each gene, one inherited from each parent. If both alleles are the same, you’re homozygous for that gene; if they’re different, you’re heterozygous. Alleles can interact in ways that determine the trait you show, with some being dominant and others recessive.

The other terms don’t describe alternative forms of the same gene: an autosome is a non-sex chromosome, a carrier is someone who has a recessive allele without showing the trait, and a chromosome is the whole DNA-containing structure.