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← Theoretical 1

Q3 — Amylase Activity — Starch Hydrolysis at 50–70°C

Theoretical 1 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Enzyme Kinetics & Regulation Carbohydrate Chemistry & Biology

The diagram shows experimental data comparing the hydrolysis of starch by amylase at 3 different temperatures.

Glucose concentration vs. time for amylase at 50°C, 60°C, and 70°C. Glucose concentration (arbitrary units) vs. time, for amylase-catalysed starch hydrolysis at 50°C, 60°C, and 70°C. The 50°C curve reaches the highest final glucose level and is still rising at 60 minutes; the 60°C curve plateaus earlier at a lower level; the 70°C curve rises fastest at first but plateaus soonest, at the lowest final level.

What conclusion can be drawn from these data? Determine whether the following statements are true or false:

A. 50°C is the optimal temperature for the initial activity of amylase.
B. At 60°C, all starch is hydrolyzed after 30 minutes.
C. At 70°C amylase is denatured before hydrolysis is complete.
D. The initial reaction rate of starch hydrolysis at 60°C is higher than at 70°C.
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Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)