Assertion: In humans, the gamete contributed by male determines whether the child produced will be male or female.
Reason: Sex in humans is polygenic trait depending upon a cumulative effect of some genes on X-chromosome and some on Y-chromosome. a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion. b) If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion. c) If Assertion is true but the Reason is false. d) If both Assertion and Reason are false.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
B. If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion.
C. If Assertion is true but the Reason is false.
D. If both Assertion and Reason are false.

Answer

To solve the assertion-reason question, we will analyze both the assertion and the reason step by step.

### Step 1: Analyze the Assertion
The assertion states: "In humans, the gamete contributed by male determines whether the child produced will be male or female."

- In humans, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).
- During reproduction, the male contributes either an X or a Y chromosome through his sperm.
- If the sperm carries an X chromosome, the resulting child will be female (XX). If it carries a Y chromosome, the child will be male (XY).

**Conclusion for Step 1**: The assertion is true.

### Step 2: Analyze the Reason
The reason states: "Sex in humans is a polygenic trait depending upon a cumulative effect of some genes on X-chromosome and some on Y-chromosome."

- A polygenic trait is one that is influenced by multiple genes.
- However, sex determination in humans is primarily controlled by the presence of the X and Y chromosomes, which is a monogenic trait, meaning it is determined by a single gene (specifically, the SRY gene on the Y chromosome).
- Therefore, the assertion that sex is polygenic is incorrect.

**Conclusion for Step 2**: The reason is false.

### Final Conclusion
- The assertion is true, but the reason is false.
- Hence, the correct answer is option **C**: If Assertion is true but the Reason is false.

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