Amylase is an enzyme found in saliva. What is its substrate and product?

• A. Substrate - starch; Product - maltose
• B. Substrate - starch; Product - glucose
• C. Substrate - cellulose; Product - sugar
• D. Substrate - glucose; Product - maltose

Answer: (A)

Amylase in saliva starts carbohydrate digestion by acting on starch, a polysaccharide made of glucose units. It breaks the alpha-1,4 glycosidic bonds in starch, cutting the long chains into smaller pieces, with maltose being the main disaccharide produced. So the substrate is starch and the product is maltose. This initial step kicks off starch digestion in the mouth, and maltose can later be converted to glucose by maltase in the small intestine. Other options don’t fit because saliva amylase doesn’t start from glucose or cellulose, and it doesn’t yield glucose directly in this initial reaction.