Boiled diastase fails to hydrolyze starch

Steps:

• Boiling denatures diastase, inactivating the enzyme.
• Untreated starch remains intact after 15 minutes.
• Iodine reacts with starch to produce blue-black color.
• Benedict's reagent detects no reducing sugars, staying blue.

Why A is correct:

• Inactivated enzyme leaves starch unchanged, yielding blue-black with iodine (starch test) and blue with Benedict's (no reducing maltose).

Why the others are wrong:

• B: Benedict's red indicates reducing sugar, but no maltose forms.
• C: Iodine brown suggests absent starch, but starch persists.
• D: Iodine brown wrongly implies starch breakdown.

Final answer: A