Final answer:
Crossing-over, independent assortment, and random fertilization are biological processes that lead to genetic variation in sexually reproducing organisms.
Step-by-step explanation:
Crossing-over, independent assortment, and random fertilization are all processes that contribute to genetic diversity in sexually reproducing organisms.
Crossing-over occurs during meiosis when homologous chromosomes exchange segments of genetic material. This results in new combinations of alleles on the chromosomes, increasing genetic diversity.
Independent assortment happens during meiosis when homologous pairs of chromosomes randomly align at the metaphase plate, leading to different combinations of chromosomes in the resulting gametes.
Random fertilization occurs when a sperm cell randomly fertilizes an egg cell, bringing together two different sets of chromosomes. Each gamete has the potential to combine with any other gamete, resulting in countless genetic combinations and further increasing genetic diversity.