After your body has used the glucose to do all the work it needs to do, there is waste material left over.

Your body gets rid of the waste through breathing out, sweat and going to the toilet. Your lungs get rid of the air, your bowels process solid wastes and your kidneys turn liquid waste into urine. 

The liver produces a waste product called bilirubin. This comes from the red pigment in red blood cells. It is yellow and it is the substance that makes the bile yellow and your poo brown.