Difficulty: Hard

Average Score: 25%

Which of the following is a true statement about an X-linked trait?

Rationale

A father can pass the trait to his daughters but not to his sons.

X-linked traits are associated with genes located on the X chromosome. Since males have one X and one Y chromosome, they inherit their X chromosome from their mothers and pass their Y chromosome to their sons, making it impossible for them to pass X-linked traits to their sons.

A (A mother can pass the trait to her daughters but not to her sons.) YOUR ANSWER

This statement is incorrect because a mother can indeed pass an X-linked trait to both her daughters and her sons. Sons inherit their mother's X chromosome, which can carry the X-linked trait, while daughters inherit one X chromosome from each parent.

B (A mother can pass the trait to her sons but not to her daughters.) YOUR ANSWER

This statement is false as well. A mother can pass the X-linked trait to both her sons and daughters. Sons receive their X chromosome from their mother, and daughters receive one X chromosome from each parent, making this statement inaccurate.

D (A father can pass the trait to his sons but not to his daughters.) YOUR ANSWER

This statement is incorrect because a father cannot pass his X-linked traits to his sons, as sons inherit the Y chromosome from their father. However, fathers can pass their X-linked traits to their daughters, who receive their father's X chromosome.

Conclusion

Understanding the inheritance patterns of X-linked traits is crucial for predicting genetic outcomes. In this context, the ability of a father to pass an X-linked trait exclusively to his daughters, while his sons inherit the Y chromosome, highlights the unique transmission of X-linked genes. Thus, choice C accurately represents the inheritance pattern of X-linked traits.

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