Final answer:
Meiosis is crucial for sexual reproduction as it produces haploid gametes with genetic variation and ensures the correct chromosome number in offspring. It involves genetic crossover and chromosome number reduction, which is not the case with Mitosis. Errors in Meiosis can lead to chromosomal disorders such as Down syndrome.
Step-by-step explanation:
It is important to perform Meiosis rather than Mitosis in certain conditions because Meiosis allows for the production of haploid gametes necessary for sexual reproduction in diploid organisms. During Meiosis, homologous chromosomes pair and undergo genetic variation through crossover events, an essential step for the generation of genetic diversity in offspring. Furthermore, Meiosis reduces the number of chromosomes by half, ensuring that when two gametes unite during fertilization, the resultant zygote has the appropriate diploid number of chromosomes. In contrast, Mitosis results in the formation of identical cells for growth or repair and does not provide genetic variation or reduce the number of chromosomes.
Chromosomal disorders can arise from errors in Meiosis, such as nondisjunction, which leads to abnormal chromosome numbers in the gametes and can result in conditions like Down syndrome. Meiosis is regulated by a variety of internal signals and external factors and has evolved to balance the need for fidelity in chromosome segregation with the benefits of genetic diversity. Understanding the mechanisms and evolution of Meiosis can provide insights into the complex biological processes that underpin sexual reproduction and genetic inheritance.