Assertion :- Colchicine induces polyploidy
Reason : Colchicine causes disjucation of chromosomes.

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "Colchicine induces polyploidy." Polyploidy refers to the condition where a cell has more than two complete sets of chromosomes. Colchicine is known to induce polyploidy, especially in plant cells.

2. **Understanding the Reason**: The reason given is "Colchicine causes disjunction of chromosomes." Disjunction refers to the separation of chromosomes during cell division. However, colchicine actually inhibits this process rather than causing it.

3. **Mechanism of Action of Colchicine**: Colchicine interferes with the normal process of cell division (mitosis) by inhibiting the polymerization of microtubules. Microtubules are essential for the formation of spindle fibers, which are necessary for the proper segregation of chromosomes during cell division.

4. **Effect of Colchicine on Chromosome Segregation**: Since colchicine inhibits the formation of spindle fibers, it prevents the proper segregation of chromosomes. This leads to a situation where chromosomes do not separate correctly, which can result in one daughter cell receiving more than the normal haploid set of chromosomes, thereby leading to polyploidy.

5. **Conclusion on Assertion and Reason**:
- The assertion is true because colchicine does induce polyploidy.
- The reason is false because colchicine does not cause disjunction; rather, it inhibits the segregation of chromosomes.

6. **Final Evaluation**: Therefore, the correct evaluation is that the assertion is true, and the reason is false.

**Final Answer**: Assertion is true, Reason is false.

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