Why do certain cells undergo meiosis in living organisms?

Meiosis produces haploid cells, which means that they have half the number of chromosomes and therefore half the genetic material of most normal cells. It is necessary for genital cells to be haploid so that when two combine, the result is a zygote with a normal diploid number of chromosomes. If the genital cells were diploid, then there would be twice as many chromosomes in the resulting zygote, and throughout the generations, the cells would have more and more genetic material and would become so large in order to hold all of this that they would no longer function. Meiosis is necessary for genital cells to be haploid.