Where does starch digestion begin?  

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Starch digestion begins in the mouth.

In the mouth, salivary glands secrete saliva. The saliva helps to moisten the food. The saliva also contains salivary amylase. Salivary amylase is an enzyme. Enzyme are biological catalysts that serve to increase the rate of reaction by lowering the activation energy required to initiate a reaction. Each enzyme is specific to a certain substrate. The specificity occurs because the shape of the enzyme and the shape of the substrate are complementary to one another.  

The shape of the enzyme amylase is specific to the shape of starch. Starch is a branched carbohydrate made of many monosaccharides. Amylase serves to catalyze the hydrolysis of starch into smaller units of sugar such as glucose. This process occurs in the mouth.

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