2.28 Explain how and why food is moved through the gut by peristalsis

Food moves down the oesophagus through a process known as peristalsis. This is when the two sets of muscles in the gut contract, creating a squeezing action that moves the food down. 

This is necessary because food needs to be mechanically moved to get through the digestive system. 

Source: BBC BitesizeFigure 1: Peristalsis