Which process includes the formation of haploid cells?

The formation of haploid cells occurs during meiosis, which is a specialized type of cell division that reduces the chromosome number by half, resulting in four genetically distinct haploid cells from one diploid cell. This process is crucial for sexual reproduction because it produces gametes (sperm and eggs) that contain one set of chromosomes.

In detail, meiosis consists of two consecutive divisions—meiosis I and meiosis II. During meiosis I, homologous chromosomes are separated, which reduces the chromosome number from diploid (two sets) to haploid (one set). Then, meiosis II resembles mitosis but does not further reduce the chromosome number, as it separates the sister chromatids of each chromosome, resulting in four haploid daughter cells.

The other processes involve diploid cells or do not lead directly to the formation of haploid cells. Mitosis maintains the diploid chromosome number, whereas fertilization combines two haploid gametes to form a diploid zygote. Cloning produces genetically identical diploid organisms, thus not contributing to haploid cell formation.