Final answer:
Crossing over, a process of genetic recombination that occurs during meiosis, leads to the exchange of genetic material between homologous chromosomes, creating unique gene combinations and contributing to genetic variation among offspring.
Step-by-step explanation:
Crossing over, which occurs during meiosis, is a process of genetic recombination that leads to the exchange of genetic material between homologous chromosomes. During prophase I of meiosis, homologous chromosomes line up in pairs, forming a tetrad. Non-sister chromatids of the homologous chromosomes can then exchange genetic material through crossover. This process creates unique combinations of genes and contributes to genetic variation among offspring.