Final answer:
Mechanical digestion is the physical breakdown of food into smaller pieces. It occurs mainly in the mouth and stomach through processes like chewing and churning. The increased surface area of the food particles allows for effective action by digestive enzymes.
Step-by-step explanation:
Mechanical digestion is the physical breakdown of chunks of food into smaller pieces. This type of digestion takes place mainly in the mouth and stomach. It includes processes such as chewing and the churning of food in the stomach. Mechanical digestion increases the surface area of food particles, making them easier to be acted upon by digestive enzymes.