Final answer:
Crossing over in meiosis results in the exchange of genetic material between non-sister chromatids of homologous chromosomes, leading to new combinations of maternal and paternal alleles on the same chromosome.
Step-by-step explanation:
When homologous chromosomes cross over in meiosis, the result is an exchange of corresponding segments of non-sister chromatids. This process, also known as recombination or crossover, does not alter the linear order of genes on the chromosomes. Instead, it combines maternal and paternal alleles onto the same chromosome, creating unique combinations of genes. Throughout the length of the synapsed chromosomes, multiple crossovers can occur, leading to a substantial shuffling of alleles and consequently, a significant amount of genetic variation.
During prophase I of meiosis, homologous chromosomes line up gene-for-gene, forming a tetrad structure, which enables this exchange. This genetic recombination plays a crucial role in increasing genetic diversity among gametes, which is important for the evolution and adaptability of species.