What ensures genetic variation during meiosis?

The process of independent assortment during meiosis is crucial for ensuring genetic variation. This occurs during metaphase I of meiosis, where homologous chromosome pairs align independently at the cell's equatorial plane before being separated into gametes. Each pair of chromosomes can orient in two possible ways with respect to the poles of the cell, meaning the combination of maternal and paternal chromosomes that end up in each gamete can vary significantly.

This random orientation leads to a mix of maternal and paternal genetic material being passed on, contributing to genetic diversity in the resulting gametes. When combined with other mechanisms such as crossing over—where sections of DNA are exchanged between homologous chromosomes—the variation increases even further, leading to unique combinations of genes in offspring.

The other options, such as duplication of DNA and replication of chromosomes, are essential processes for preparing for cell division but do not directly contribute to the shuffling of genetic material that occurs in meiosis. Binary fission, on the other hand, is a form of asexual reproduction in prokaryotes and does not pertain to meiosis or the generation of genetic variation in sexually reproducing organisms.