Final answer:
Meiosis is a cell division process that results in four genetically unique haploid cells from a diploid nucleus. The two stages, Meiosis I and Meiosis II, reduce chromosome numbers by half and contribute to genetic diversity.
Step-by-step explanation:
Meiosis is a nuclear division process that reduces the chromosome number by half and is responsible for producing haploid cells from a diploid nucleus. It is an essential component of sexual reproduction, used by diploid organisms to produce gametes such as sperm and eggs. Unlike mitosis, which results in daughter cells that are genetically identical to the parental cell, meiosis includes two rounds of cell division, Meiosis I and Meiosis II, resulting in four unique haploid daughter cells.
During Meiosis I, which is the first round of meiotic cell division, a single round of chromosome replication is followed by the cell being divided into two haploid cells. This is often referred to as reduction division because the ploidy level is halved from diploid to haploid. Meiosis II follows without another round of chromosome replication. Instead, sister chromatids are separated into four genetically distinct haploid cells, each with half the chromosome sets as the original diploid cell.
Crossing over and random alignment during Meiosis I contribute to genetic diversity by creating new combinations of genes. The result is that each of the four haploid cells is genetically unique, a key aspect of sexual reproduction that enhances genetic variability among offspring.