Assertion : Small cells are metabolically less active
Reason : K.I. of small cells is less.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion and Reason:**
- The assertion states that "small cells are metabolically less active."
- The reason provided is that "K.I. (karyotypic index) of small cells is less."

2. **Analyzing the Assertion:**
- The assertion claims that smaller cells are less metabolically active. However, this is incorrect. Smaller cells tend to have a higher metabolic rate because they have a more favorable surface area-to-volume ratio, allowing for more efficient transport of materials in and out of the cell.

3. **Analyzing the Reason:**
- The reason states that the K.I. of small cells is less. The K.I. (karyotypic index) refers to the ratio of the number of chromosomes to the volume of the cell. In smaller cells, the nucleus-to-cytoplasm (N/C) ratio is closer to 1, which means that the nucleus is proportionally larger compared to the cytoplasm. This allows for more efficient metabolic processes.

4. **Conclusion:**
- Since the assertion is false (small cells are not less metabolically active) and the reason is also false (the K.I. of small cells is not less), we conclude that both the assertion and the reason are incorrect.

5. **Final Answer:**
- Therefore, the correct option is D: Both assertion and reason are false.

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