When would an organism need to undergo the process or mitosis? Meiosis?

Question

When would an organism need to undergo the process or mitosis? Meiosis?

Answer 1

Cells of an organism undergo mitosis to repair damaged cells or when an organism is growing.  Cells undergo meiosis to produce gametes, which are s*x cells.  Gametes fuse during reproduction to form a zygote, which develops into an embryo which then becomes an organism.  Embryonic cells undergo mitosis as the organism develops.

Answer 2

Mitosis - growth and repair.

Meiosis - production of gametes.