Praxis II: Biology Content Knowledge Exam Prep

Answer: D, The statement that is true about sex-linked traits is that Y-linked traits can only be inherited from the father. Since the father is the only parent with a copy of the Y-chromosome, only he can pass that trait on to offspring.

Key Takeaway: Sex linkage is the phenotypic expression of an allele (i.e. trait) that is related to the chromosomal sex of an individual. Sex-linked traits are not equally inherited by the sexes, which is the opposite of autosomal traits. In humans, X-linked traits are more common, as the X-chromosome is bigger and has more genes. X-linked traits can be inherited from either parent and inherited by offspring of either sex, but Y-linked traits are only inherited from the father and can only be inherited by males.