Which term describes traits expressed by genes on X or Y chromosomes?

Which term describes traits expressed by genes on X or Y chromosomes?

• A. Autosomal traits
• B. Sex-linked traits
• C. Mitochondrial traits
• D. Quantitative traits

Answer: (B)

Sex-linked traits are determined by genes on the sex chromosomes, X or Y. This matters because the X chromosome carries many genes and, in humans, males have only one X while females have two. A gene on X can be expressed in a male with just that one copy, so X-linked alleles often show up differently in men and women. In contrast, autosomal traits are on non-sex chromosomes, mitochondrial traits come from the mother via mitochondria, and quantitative traits are measured on a continuous scale and aren’t defined by being on sex chromosomes. Therefore, the term that describes traits expressed by genes on the X or Y chromosomes is sex-linked traits.

Sex-linked traits are determined by genes on the sex chromosomes, X or Y. This matters because the X chromosome carries many genes and, in humans, males have only one X while females have two. A gene on X can be expressed in a male with just that one copy, so X-linked alleles often show up differently in men and women. In contrast, autosomal traits are on non-sex chromosomes, mitochondrial traits come from the mother via mitochondria, and quantitative traits are measured on a continuous scale and aren’t defined by being on sex chromosomes. Therefore, the term that describes traits expressed by genes on the X or Y chromosomes is sex-linked traits.