Which statement explains why amylase does not produce a positive Benedict's test on cellulose?

• A. Because Benedict's test does not detect cellulose
• B. Because buffer inhibits Benedict's reagent
• C. Because cellulose is already hydrolyzed
• D. Because amylase cannot digest cellulose

Answer: (D)

Enzyme specificity and Benedict's test for reducing sugars are being examined. Amylase works on starch, breaking its alpha-1,4 bonds to yield reducing sugars like maltose and glucose, which Benedict’s reagent detects. Cellulose, on the other hand, is built from glucose units linked by beta-1,4 bonds, and amylase cannot cleave those bonds. Because amylase cannot digest cellulose, no reducing sugars are produced to react with Benedict’s reagent, so the test stays negative. If cellulose were broken down by a cellulose-digesting enzyme into reducing sugars, Benedict’s test could become positive.