Air is made up of several gases, but the two most important gases are Oxygen and Carbon dioxide. Without oxygen, animals will die, and without carbon dioxide, plants cannot survive<span>. Food (nutrients): Living things need energy for function. Energy is needed to grow, reproduce, move, and to work.</span>
Because the cell is considered an organelle which is a biological mechanism which consists of different parts, whereas a molecules is a single part and not a mechanism.