Mitosis and Meiosis are fundamental processes of life. To keep life going, cells must multiply, heal itself or reproduce. Mitosis is a type of cell division which occurs in the somatic cells to maintain the number of chromosomes in the parent cell. So, this type of cell division is important for growth and tissue repair while Meiosis is a special type of cell division that reduces the chromosome number from 2n to n and it helps in the formation of gametes. Without mitosis, there would not be any growth and the worn-out cells would not be replaced, and without meiosis, the organism would not be able to reproduce effectively.
So, both Mitosis and Meiosis are the two cellular processes that are essential for the existence of life.