Answer:
Crossing over occurs during prophase I of meiosis before tetrads are aligned along the equator in metaphase I.
Step-by-step explanation:
When chromatids "cross over," homologous chromosomes trade pieces of genetic material, resulting in novel combinations of alleles, though the same genes are still present. Crossing over occurs during prophase I of meiosis before tetrads are aligned along the equator in metaphase I.