What happens in meiosis ?

Options

A. One division of nucleus and one division of chromosomes
B. Two divisions of nucleus and one division of chromosomes
C. Two divisions of nucleus and three divisions of chromosomes
D. One division of nucleus and two divisions of chromosomes

Answer

**Step-by-Step Solution:**

1. **Understanding Meiosis**: Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in the formation of four haploid gametes (sperm or eggs). This process is essential for sexual reproduction.

2. **Chromosome Duplication**: Before meiosis begins, the cell undergoes a process called DNA replication during the S phase of interphase. This results in duplicated chromosomes, each consisting of two sister chromatids.

3. **Two Divisions**: Meiosis consists of two sequential divisions:
- **Meiosis I**: This is the first division where homologous chromosomes are separated. It includes:
- Prophase I: Homologous chromosomes pair up and exchange genetic material (crossing over).
- Metaphase I: Paired chromosomes align at the cell's equatorial plane.
- Anaphase I: Homologous chromosomes are pulled to opposite poles.
- Telophase I: The cell divides into two haploid cells.

- **Meiosis II**: This is the second division where sister chromatids are separated. It includes:
- Prophase II: Chromosomes condense again in the two haploid cells.
- Metaphase II: Chromosomes align at the equatorial plane of each haploid cell.
- Anaphase II: Sister chromatids are pulled apart to opposite poles.
- Telophase II: The cells divide again, resulting in a total of four haploid gametes.

4. **Final Outcome**: The end result of meiosis is four genetically diverse haploid cells, each with half the number of chromosomes of the original cell.

5. **Conclusion**: Therefore, in meiosis, there is one duplication of chromosomes and two divisions of the nucleus.

**Final Answer**: In meiosis, there is one duplication of chromosomes and two divisions of the nucleus.

---