14. Long answer questions I

 

Our mouth physically breaks down food into small pieces when we eat. In the mouth, stomach, and abdominal,mouth, stomach, and lungs,mouth, stomach, and small intestine, mechanical digestion occurs. Food is chemically changed in digestion when new, smaller substances are formed. Furthermore, we will never get the raw material back in the same condition as before. Food digestion is a permanent (chemical change) and reversible irreversible change.