Cell replication is meant to be a very regulated process. Messages are sent to the cell, telling it when to duplicate and when not to. When cells divide according to their natural plan, then there are no problems. However, when cells either do not receive those messages or misinterpret them, they can divide too fast and without pause. These renegade cells are what we call cancer cells.
B. xylem and phloem. they transport water and nutrients throughout the plant
