A : One drum stick nucleus is present in the neutrophil of normal female.
R : It is absent in the neutrophil of male.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true and the reason is not the correct explanation of the assertion , then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion (A)**: The assertion states that "One drumstick nucleus is present in the neutrophil of normal female." This refers to the presence of a Barr body, which is a condensed X chromosome found in females. In neutrophils, this Barr body appears as a drumstick-shaped structure.

2. **Understanding the Reason (R)**: The reason states that "It is absent in the neutrophil of male." In males, there is only one X chromosome, and therefore, there is no need for a Barr body to form, as there is no second X chromosome to inactivate.

3. **Scientific Background**: The presence of Barr bodies is a result of X-inactivation, a process where one of the two X chromosomes in females is randomly inactivated to balance gene dosage between males (XY) and females (XX). This inactivated X chromosome forms a Barr body.

4. **Calculating the Number of Barr Bodies**: The number of Barr bodies can be calculated using the formula N-1, where N is the number of X chromosomes. For females (XX), N=2, so 2-1=1 Barr body. For males (XY), N=1, so 1-1=0 Barr bodies.

5. **Conclusion**: Both the assertion and reason are true statements. However, the reason provided does not directly explain the assertion. The presence of a Barr body in females is due to the inactivation of one X chromosome, while the absence in males is simply because they have only one X chromosome, which does not undergo inactivation.

6. **Final Answer**: Therefore, the correct answer is that both statements are true, but the reason is not the correct explanation for the assertion.

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