Question

In a family, if the father is affected by X-linked dominant trait and mother is normal, then:

• A. some of the daughters can be normal.
• B. all the daughters will be affected.
• C. all the daughters and none of the sons will be affected.
• D. all the sons and some of the daughters will be affected.

Hint:

X-linked Dominant Father $\rightarrow$ 100% Affected Daughters, 0% Affected Sons.

Answer 1

The Correct Option is B

Step 1: Concept
X-linked dominant inheritance involves a gene located on the X chromosome where one copy of the allele is sufficient to cause the trait.

Step 2: Meaning
Affected Father = $X^A Y$. Normal Mother = $X X$.

Step 3: Analysis
- Daughters: Receive one X from the father and one from the mother. All daughters will receive the $X^A$ from the father. Since it is dominant, all will be affected. - Sons: Receive the Y from the father and an X from the mother. All will receive a normal X from the mother, so none will be affected.

Step 4: Conclusion
Every daughter of an affected father will inherit the trait. Final Answer: (B)