Why do cells undergoing mitosis require one set of divisions, whereas those undergoing meiosis require two sets of divisions? what is the end result of meiosis?

Mitosis, you see, is somatic (body) cell division, and the DNA in the nucleus during Interphase can replicate by doubling the chromosomes before the actual mitosis or cell division process of splitting into TWO identical cells (and they function the same with the same number of identocal chromosomes too! So they are called Diploid cells with 46 chromosomes!)

Meiosis is sperm/egg division and must divide twice to produce FOUR sperm or egg cells. Sperm goes through I- PMAT just like mitosis, but goes through PMAT again after that! They create four Haploid gametes (sex cells) with 23 chromosomes so that when an egg and a sperm unite in sexual reproduction, the zygote (fertilized egg) will have exactly 46 chromosomes like the normal number of chromosomes in a somatic cell. ^^