Ontario Grade 11 University Biology Practice Text

The process that leads to genetic variation in offspring is crossing over. This occurs during meiosis, specifically in prophase I, where homologous chromosomes exchange segments of genetic material. This exchange results in new combinations of alleles on the chromosomes, which means that the gametes produced will have different genetic information than the parental DNA. Consequently, when these gametes fuse during fertilization, the resulting offspring will exhibit genetic diversity.

Other processes, though significant in reproduction, do not inherently increase genetic variation. For instance, binary fission is an asexual reproduction method that produces identical offspring, thus keeping the genetic material of the parent cell unchanged. While spermatogenesis and oogenesis are responsible for producing sperm and eggs respectively, they primarily focus on the formation of gametes and can involve some level of genetic variation. However, crossing over specifically enables greater genetic diversity by reshuffling genetic material before the formation of gametes. Therefore, crossing over stands out as the key process contributing to genetic variation in offspring.