A sexual reproducing organism contains mostly the diploid cells (2n), which consist of two sets of chromosomes. One set is inherited from each parent. Each human cell holds 23 pairs of chromosomes in which, 22 pairs are autosomes, and the left pair contains two sex chromosomes. Meiosis is necessary to produce gametes (haploid cells) such as egg cells in female and sperm cells in the male. It is important for a sexually reproducing organism to produce haploid gametes that take part in fertilization. Each of the haploid gametes contains half the chromosomes of the parent cells which are diploid. A haploid gamete of a female fertilizes with the haploid gamete of a male and results into a diploid zygote. Meiosis is necessary for restoring the chromosome number of the parent cell, and to avoid chromosomal error in each generation. Hence, the chromosome number is not maintained in the absence of meiosis in sexually reproducing organisms.