Final answer:
Cell theory states that all cells come from existing cells and supports the process of cell division where new cells replace damaged or worn-out cells for tissue maintenance and repair.
Step-by-step explanation:
Cell theory supports the fact that new cells are created to repair damaged cells through cell division. According to the cell theory, all cells come from pre-existing cells, which explains how damaged or worn-out cells are replaced. When you cut your finger, for instance, the healing process involves cell division wherein some skin cells divide to produce new ones, allowing the wound to repair. This is also true for other cells in the body that wear out over time due to various reasons, necessitating replacement via cell division.
Every multicellular organism starts as a single cell, and through repeated cell divisions, it grows into a complex being composed of trillions of cells. Even after full growth, continual cell division is needed to maintain and repair tissues, such as producing new blood and skin cells. The cell cycle is a critical process that describes the sequence of events from the formation of a cell until it divides, ensuring regulated growth and division.