Final answer:
During meiosis, a single crossover between homologous non-sister chromatids produces two recombinant and two nonrecombinant gametes, contributing to genetic variation. The same result is achieved with genetic recombination, a critical process for diversity in resultant offspring.
Step-by-step explanation:
For each meiosis, a SINGLE crossover produces two recombinant and two nonrecombinant gametes. This is exactly the same result as genetic recombination.
Crossover events are pivotal as they are the first source of genetic variation in the nuclei produced by meiosis. When a single crossover event occurs between homologous non-sister chromatids, it leads to a reciprocal exchange of equivalent DNA segments between the chromosomes inherited from each parent.
Consequently, a recombinant chromatid that is moved into a gamete will carry DNA from both the maternal and paternal chromosomes, creating a new combination of genes that did not exist before the crossover. Ultimately, this process results in two recombinant and two nonrecombinant chromatids, which, upon segregation, lead to the formation of gametes carrying these varied genetic traits.
Moreover, this event occurs during prophase I, when homologous chromosomes align gene-for-gene, forming a tetrad structure. The process of recombination that occurs here is critical to increasing the diversity of the genetic material that will be found in offspring, contributing to the phenomenon whereby, for example, human couples have the potential to produce a vast number of genetically unique children.