Haploid cells undergo a type of cell division known as meiosis. Meiosis is a specialized form of cell division that occurs in the reproductive cells of organisms, leading to the formation of gametes (sperm and eggs) with half the number of chromosomes compared to the parent cell. This reduction in chromosome number is essential for sexual reproduction and the formation of genetically diverse offspring.

Here is a detailed explanation of meiosis in haploid cells:

1. Introduction to Meiosis:
- Meiosis consists of two sequential divisions, known as meiosis I and meiosis II.
- The process begins with a cell containing a diploid (2n) number of chromosomes.
- Diploid cells have two sets of chromosomes, one from each parent.

2. Meiosis I:
- Meiosis I is a reduction division that consists of four distinct phases: prophase I, metaphase I, anaphase I, and telophase I.
- Prophase I: The chromosomes condense, and homologous chromosomes pair up to form tetrads. Crossing over, the exchange of genetic material, occurs between the chromosomes.
- Metaphase I: The tetrads align along the metaphase plate, with spindle fibers attaching to each chromosome.
- Anaphase I: The homologous chromosomes separate and move towards opposite poles of the cell, pulled by spindle fibers.
- Telophase I: The chromosomes reach the poles, and the nuclear membrane reforms around each set, resulting in two haploid cells.

3. Meiosis II:
- Meiosis II is similar to mitosis, but it starts with haploid cells and does not involve DNA replication.
- Meiosis II consists of prophase II, metaphase II, anaphase II, and telophase II.
- Prophase II: The nuclear membrane breaks down, and the chromosomes condense.
- Metaphase II: The chromosomes align along the metaphase plate, and spindle fibers attach to each chromatid.
- Anaphase II: The sister chromatids separate and move towards opposite poles.
- Telophase II: The chromosomes reach the poles, and nuclear membranes form around each set, resulting in four haploid cells.

4. Genetic Variation:
- Meiosis plays a crucial role in generating genetic diversity.
- During prophase I, crossing over occurs, resulting in the exchange of genetic material between homologous chromosomes.
- Additionally, the independent assortment of chromosomes during metaphase I leads to further genetic variation.

In conclusion, haploid cells undergo meiosis, a specialized type of cell division that involves two rounds of division (meiosis I and meiosis II). Meiosis I reduces the chromosome number, while meiosis II separates the sister chromatids, resulting in the formation of four haploid cells. This process is essential for sexual reproduction and generates genetic diversity through mechanisms such as crossing over and independent assortment.

mitosis b/c meiosis leads to decrease in cell no. and mitosis inc. as it is haploid so in haploid always mitosis occur as to increase the no. per cell refer 1chapter of 12 carefully