Now, when we want to break down glycogen, we can easily break down glycogen because we have the proteins, the enzymes that are able to break down glycogen into the individual constituents, the glucose molecules. And then we can use the glucose molecules in the process of glycolysis and the crept cycle to basically form the ATP molecules, the energy molecules which are used by our cells. So even though glycogen is not directly used as the energy source, we transform glycogen into something that we can use as an energy source, namely the high energy adenosine triphosphate molecules. Now, let's move on to starch. So if glycogen is the energy storage in animals and humans, starch is the energy storage in plant. So the most common polysaccharide in plants used for energy storage is starch.