Which shows the best connection between the digestive and excretory systems? The digestive system fuels the cells and the excretory system rids the body of the cells' waste. The digestive system rids the body of the cells' waste and the excretory system fuels the cells. The digestive system does physical digestion while the excretory system carries out chemical digestion. The digestive system carries out chemical digestion while the excretory system does physical digestion.