Boiled diastase fails to digest starch

Steps:

• Boiling denatures diastase, rendering the enzyme inactive.
• Inactive diastase cannot hydrolyze starch into maltose over 15 minutes.
• Undigested starch reacts with iodine to form a blue-black complex.
• Absence of reducing sugars (maltose) means Benedict's solution stays blue, showing no reaction.

Why A is correct:

• Denaturation by boiling inactivates enzymes, per protein structure principles, so starch persists (blue-black with iodine) and no reducing sugars form (blue with Benedict's).

Why the others are wrong:

• B: Benedict's red indicates reducing sugars, but none are produced without active enzyme.
• C: Iodine brown suggests no starch, but undigested starch is present.
• D: Iodine brown incorrectly implies starch absence despite inactive enzyme.

Final answer: A