Final answer:
Crossing-over and independent assortment contribute to the genetic variation of gametes produced in meiosis.
Step-by-step explanation:
During meiosis, crossing-over and independent assortment contribute to the genetic variation of gametes produced. Crossing-over occurs during prophase I when homologous chromosomes exchange genetic material through the breakage and rejoining of DNA strands, resulting in new combinations of alleles on the chromosomes. This creates genetic variation as each offspring receives a unique combination of genes from both parents.
Independent assortment occurs during metaphase I when homologous pairs of chromosomes line up randomly along the equator of the cell, leading to different combinations of chromosomes in the resulting gametes. This further contributes to genetic variation as each offspring has the potential to inherit a different combination of chromosomes from their parents.