Atoms have a tendency to complete their outer shell or energy level. this is known as

Atoms have a tendancy to complete their outer shell or energy level. this is known as the octet rule.

Answer is octet rule

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.