Which of the following enzymes act on carbohydrates?

Step 1: Analyze the question The question asks which enzyme acts on carbohydrates. So we need to match each enzyme to the food class (substrate) it digests.

Step 2: Key concept Enzymes are named after or grouped by their substrates:

• Carbohydrases break down carbohydrates (e.g., amylase, maltase, sucrase, lactase).
• Proteases break down proteins (e.g., pepsin, trypsin, renin).
• Lipases break down fats and oils.

Step 3: Check each option

• A. Amylase: Digests starch into maltose. Found in saliva (salivary amylase/ptyalin) and pancreatic juice. It acts on carbohydrates. ✔
• B. Lipase: Converts fats and oils into fatty acids and glycerol. ✘
• C. Pepsin: Works in the stomach to break proteins into peptides. ✘
• D. Renin: Works in the stomach of infants to curdle milk protein (casein). It acts on protein. ✘
• E. Trypsin: Pancreatic enzyme that breaks proteins into peptides. ✘

Step 4: Answer Only amylase acts on carbohydrates, so the answer is A.

Exam tip: Look at the ending "-ase" and remember the substrate pattern: amylase → starch, lipase → lipids, protease → protein. Also remember that "pep-", "tryp-" and "ren-" enzymes are all protein-digesting. Starch → maltose (amylase), maltose → glucose (maltase).