In which the number of chromosomes is halved ?

Options

A. Mitosis
B. Amitosiss
C. Meiosis
D. Fertilisation

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which type of cell division results in the halving of the number of chromosomes.

2. **Analyzing Mitosis**: Mitosis is a type of cell division that results in two daughter cells that are genetically identical to the parent cell. The number of chromosomes remains the same (2n to 2n). Therefore, mitosis does not halve the number of chromosomes.

3. **Analyzing Amitosis**: Amitosis is another form of cell division that is similar to mitosis. It is also an equational division where the chromosome number does not change. Thus, amitosis does not halve the number of chromosomes.

4. **Analyzing Fertilization**: Fertilization is the process where two gametes (sperm and egg) fuse to form a zygote. This process increases the chromosome number, as it combines the chromosomes from both gametes. Therefore, fertilization does not halve the number of chromosomes.

5. **Analyzing Meiosis**: Meiosis is a specialized type of cell division that occurs in the formation of gametes (sperm and egg). It is known as a reductional division because it reduces the chromosome number by half. If the starting number of chromosomes is 2n, meiosis results in cells with n chromosomes.

6. **Conclusion**: Since meiosis is the only division that reduces the chromosome number by half, the correct answer to the question is **meiosis**.

**Final Answer**: The number of chromosomes is halved during **meiosis**.

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