The term used for a gene's fixed position on a chromosome is:

The term used for a gene's fixed position on a chromosome is:

• A. Chromosome arm
• B. Genotype
• C. Locus
• D. Allele

Answer: (C)

The main idea here is how we describe where a gene sits on a chromosome. The term used for a gene’s fixed position on the chromosome is locus. It’s the exact spot along the chromosome where the gene is located, like an address. Different versions of the gene, called alleles, can occupy that same locus, which is why alleles are described as variants at a locus. The other terms refer to different ideas: a chromosome arm is just part of the chromosome, a genotype is the pair of alleles an individual has for a gene, and an allele is a particular version of the gene. So the fixed position term is locus.

The main idea here is how we describe where a gene sits on a chromosome. The term used for a gene’s fixed position on the chromosome is locus. It’s the exact spot along the chromosome where the gene is located, like an address. Different versions of the gene, called alleles, can occupy that same locus, which is why alleles are described as variants at a locus. The other terms refer to different ideas: a chromosome arm is just part of the chromosome, a genotype is the pair of alleles an individual has for a gene, and an allele is a particular version of the gene. So the fixed position term is locus.