The state of a material depends on what

The state of a material depends on temperature, but also on pressure. Take water for example:
it will turn solid below 0°C, gas above 100°C, and liquid in between. Also, the boiling and freezing points depend on the pressure levels. 

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.