Which best differentiates between chemical digestion and mechanical digestion?
chemical digestion happens in the small intestine; mechanical digestion happens in the mouth.
chemical digestion involves the breaking down of food with enzymes;
mechanical digestion is breaking down food by chewing and tearing with teeth.
chemical digestion is the breakdown of fats; mechanical digestion is the breakdown of proteins.
chemical digestion is done only by the major structures of the digestive system; mechanical digestion is done by the accessory structures of the digestive system.

 The Best answer to the question stated above is "Chemical digestion involves the breaking down of food with enzymes; 
mechanical digestion is breaking down food by chewing and tearing with teeth. "

Mechanical digestion prepares food for chemical digestion.  It involves the chewing and mixing food with saliva, churning of food in the stomach, segmentation of intestines rhythmic local constrictions of intestine, causes mixing improves absorption. On the other hand chemical digestion breaks down complex food molecules into chemical building blocks, enzymes secreted into alimentary canal lumen.

Thats bot a question