Why are nonvascular plants so small

Nonvascular plants don't have a vascular system, and they're small because their lack of vascular system means that they don't have any of the mechanics required for carrying food and water far lengths or any certain distance.

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.