1. Growth and Development: Mitosis is essential for the growth and development of multicellular organisms. From the very first division of a fertilized egg, mitosis creates more cells, increasing the size and complexity of the organism. Think of it like building a house - you need to create more bricks (cells) to make the house (organism) bigger and more complex.

2. Repair and Replacement: Our bodies are constantly experiencing wear and tear. Cells can be damaged due to injury or normal aging. Mitosis allows for the replacement of these damaged or lost cells, keeping our tissues healthy and functioning. This is like fixing a broken window in a house - you need to replace the damaged piece (cell) with a new one (through mitosis) to restore functionality.