Final answer:
Crossing-over or recombination is the process where homologous chromosomes exchange genetic material during prophase I of meiosis I, leading to genetic diversity.
Step-by-step explanation:
The process being described is known as crossing-over or recombination. Crossing-over is a critical event during prophase I of meiosis I, where homologous chromosomes pair up and exchange segments of genetic material. This exchange can happen multiple times within the same pair of chromosomes, resulting in a mix of maternal and paternal alleles on each chromosome.
Such genetic recombination contributes to genetic diversity by shuffling alleles between the homologs, producing recombinant chromosomes that carry genes from both parents. During this stage, chromosomes line up in pairs, and reciprocal exchanges of chromosome segments take place at points known as chiasmata, where non-sister chromatids come into contact. This leads to two recombinant and two non-recombinant chromosomes, significantly contributing to variation in the genetic make-up of offspring.