Q. For the biological diversity is meiosis or mitosis the more important process?
Meiosis is the cell division process that allows the formation of gametes to sexual reproduction with aleatory separation of each chromosome of the individual homologous pairs. These gametes can fecundate gametes from other individuals promoting combination of homologous chromosomes from diverse individuals. In that manner the chromosomal recombination provided by meiosis and sexual reproduction creates individuals with different genetic patrimony from their fathers and thus promotes biological diversity.
Some fungi plants and species for instance, present sporic meiosis that is a structure where half of the chromosomes of the species are generated from meiosis. This structure by mitosis forms gametes. Even in this case variety comes from meiosis. Meiosis then is the cell division procedure that in conjunction with genetic mutations is responsible for the biological multiplicity.
Even in species having zygotic meiosis the aleatory division of homologous chromosomes in meiosis create biological diversity.