Final answer:
During prophase I, crossing-over occurs, and in metaphase I, a random assortment of chromosomes leads to unique combinations of maternal and paternal chromosomes in the gametes.
Step-by-step explanation:
Meiosis I is a two-step process that plays a crucial role in genetic diversity. During prophase I, homologous chromosomes pair up and exchange genetic material through a process called crossing-over. This leads to new combinations of alleles on the resulting chromosomes. In metaphase I, the homologous chromosomes line up in pairs in the middle of the cell. A random assortment of chromosomes from the mother and father occurs, creating unique combinations of maternal and paternal chromosomes in the gametes.