What term describes a trait linked to the sex chromosomes?

• A. Sex-linked trait
• B. Autosomal
• C. Carrier
• D. Heterozygous

Answer: (A)

Sex-linked describes a trait whose gene is located on the sex chromosomes. In humans, many sex-linked traits lie on the X chromosome, so inheritance patterns differ between males and females. Because males have only one X, a single recessive allele on that X will show up in their phenotype, while females would need two copies of the allele to express it (one on each X). This is why certain traits like color blindness or hemophilia often appear more in males and can be carried by females without being expressed. The other terms don’t describe the trait’s location: autosomal refers to genes on non-sex chromosomes, a carrier is someone who has a recessive allele but may not show the trait, and heterozygous describes having two different alleles for a gene, not specifically about sex chromosome linkage.