Final answer:
The Holliday model explains recombination between homologous chromosomes, a key process in genetic diversity during meiosis I.
Step-by-step explanation:
The Holliday model is used to explain recombination between homologous chromosomes. This process, commonly referred to as homologous recombination or crossing over, occurs during meiosis I, where homologous chromosomes pair up and may exchange alleles through reciprocal physical exchanges of DNA.
This genetic recombination is a source of genetic diversity, as it results in offspring having a combination of maternal and paternal genes that did not exist before the crossover event.