What is the function of peristalsis?
When does the first step of digestion usually occur?
Food enters the human body through the _____.
Order the following steps in the digestion process.
Nutrients and water in the food are absorbed
Undigested food is eliminated
Food is ingested
Food is digested
Using complete sentences, explain why is it necessary to have both mechanical and chemical digestion?
Using a complete sentence, explain how the respiratory system and the skin play a role in in the excretory system.