In metapahse I of meiosis, the homologous chromosomes line up side by side along the equator so that (a) crossing-over (exchange of DNA regions) can occur between the homologous pairs and (b) the homologous chromosomes can be pulled to opposite poles during anaphase I. In mitosis, by contrast, homologous chromosomes line up single file along the equator. What benefits are derived from these two different ways that homologous chromosomes are positioned at metaphase in meiosis and mitosis?