Final answer:
The formation of gametes does not need to take place before meiosis can begin. Meiosis involves DNA duplication and cytoplasmic changes to prepare for cellular division; gametogenesis follows meiosis.
Step-by-step explanation:
Preparation for Meiosis
Before meiosis can begin in an organism's cells, several important events must take place. DNA duplication occurs during the S-phase of the cell cycle, ensuring that each chromosome is copied to produce a pair of sister chromatids. Additionally, the production of cell organelles and an increase in cytoplasm are necessary to support the subsequent divisions and the formation of new cells. However, the event that does not need to occur before meiosis can begin is (d) the formation of the gametes. Gamete formation, or gametogenesis, is the process that meiosis contributes to; therefore, it logically follows after meiosis has occurred, not before.
During meiosis, two rounds of nuclear division happen, resulting in the creation of four genetically unique haploid cells from a single diploid parent cell. The first division separates homologous chromosomes into different cells, and the second division separates sister chromatids into individual chromosomes, similar to mitosis. Crossing over during prophase I and the random alignment of chromosomes during metaphase I contribute to genetic variation in the resulting gametes.