Fuel cells are a particular type of electrochemical cell that require a constant source of chemical fuels, or reactants, during operation. one of the most common types of fuel cells is the alkaline fuel cell which uses hydrogen and oxygen as reactants.

A fuel cell works like a battery. It consists of two electrodes where the reactions would occur and an electrolyte solution which allows for caharged particles to flow. In a fuel cell that uses hydrogen and oxygen as reactants. The hydrogen would enter the cell at the anode where oxidation would happen. So that the species that is formed in the anode side would be hydronium ions and electrons. The oxygen, on the other hand, would enter the cathode electrode where reduction occurs. The species that are produced in this side of the cell are water molecules. Together, the net reaction is called a redox reaction.

Cells of an organism tell each other when predators are near.