Leaves need to be elevated so they are exposed to sunlight for photosynthesis. which part of the stem grows to make this possible?

The answer is apical meristem.

An apical meristem is a meristem tissue found at the tips of branches. When the apical meristem is active, a tree grows in height. By growing in height, leaves will be elevated and that way exposed to the sunlight so the process of photosynthesis can take place.

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.