What purposes do crossing over and independent assortment play in cell division?

Crossing over happen when prophase I of meiosis I. It involves the exchanging of genes between the non-sister chromatids of homologues which allows the novel mixture of maternal and paternal genetic material with new, recombining chromosomes. Chromosomes maternal and paternal chromosomes line up during. Certainly, it is complete not chosen which sperm fertilizes which egg which creates even more potential variation in the offspring.