Why do you have pairs of chromosomes?

During the process of Meiosis, four haploid cells are produced. Two from sperm, and two from eggs. The goal is to form two chromosomes that have exactly half as many chromosomes as the starting cell. Before all this we start as diploid cells though. which have two sets of chromosomes. When successfully fertilized the diploid cells produce the haploid cells which only have one set of chromosomes.

  Hope this helps!

as in mitosis, dna replication occurs during interphase.   in meiosis, it occurs specifically in s phase of interphase 1.