The initial site of both mechanical and chemical digestion is the

mouth

Explanation:

Mouth is the first part of the gastrointestinal tract, more precisely its upper part. This is the site where the digestion of the food begins.

Mechanical digestion of the food refers to chewing, which breaks down the food into pieces.

Chemical digestion refers to enzymatic breakdown of the food via secretion of salivary gland located in the mouth cavity. Beside saliva, salivary glands secrete enzyme such as amylases (breakdown of the carbohydrates) and lipases (the hydrolysis of lipids).

explanation:

on disadvantage of hydroelectric power is the cost. another disadvantage of using hydroelectric power is finding a water source powerful enough to harvest hydroelectric power.