Question 38

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

An X-linked trait is one that is associated with a gene located on the X chromosome. In this case, a father can only pass his X chromosome to his daughters, thereby potentially passing on the X-linked trait, but he passes his Y chromosome to his sons, who cannot inherit the trait.

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

This statement is incorrect. A mother can pass the X-linked trait to both her daughters and her sons. Daughters receive one X chromosome from their mother, and sons receive one X chromosome from their mother as well, allowing the possibility of inheriting the trait from her.

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

This statement is also incorrect. As previously mentioned, a mother can indeed pass the X-linked trait to both her daughters and sons, making it false to claim she can only pass it to her sons.

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

This statement is true. Since fathers have one X chromosome (which carries the trait) and one Y chromosome, they can pass the X chromosome to their daughters only. Sons inherit the Y chromosome from their father, thus cannot inherit the X-linked trait from him.

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

This statement is incorrect. A father does not pass his X chromosome to his sons; instead, he passes his Y chromosome to them. Therefore, sons cannot inherit an X-linked trait from their father.

Conclusion

The correct answer is C because it accurately reflects the inheritance pattern of X-linked traits, where fathers can pass the trait to their daughters through the X chromosome, while sons inherit the Y chromosome, preventing them from receiving the trait. Options A, B, and D fail to recognize the specific inheritance patterns of X-linked traits, confirming C as the only accurate statement.