Test on Biological Molecules, Enzymes, and Digestion

Question 1: Amylase denatures due to the pH in the mouth.

A. Ano

B. Ne

Explanation: Amylase works in the mouth and digests starch into simple sugars. The study materials state that the pH in the stomach (pH 1.6-2.0) is not suitable for amylase and it would stop working there, implying the pH in the mouth is suitable and does not cause denaturation.

Question 2: Amylase digests starch into simple sugars most quickly at a temperature significantly above body temperature.

A. Ano

B. Ne

Explanation: The study materials state that starch is digested more quickly at 35°C, which is described as 'near body temperature', not significantly above it.

Question 3: According to the provided study materials, what occurs when an enzyme is heated to high temperatures beyond its optimum?

A. The enzyme's chemical bonds are broken.

B. The enzyme's active site is destroyed.

C. The enzyme loses its shape.

D. The rate of reaction increases.

Explanation: Heating to high temperatures (beyond the optimum) will break the chemical bonds that hold the enzyme together, causing it to lose its shape and destroying its active site, which is described as denaturation. The rate of reaction increases with temperature only up to an optimum, not beyond it when denaturation occurs.

Question 4: According to the study materials, what is the direct outcome when a reaction involving sucrose and enzyme bonds occurs?

A. The enzyme's active site is destroyed

B. Sucrose changes into glucose and fructose

C. The pH of the reaction becomes unsuitable for the enzyme

D. Starch is digested into simple sugars

Explanation: The study materials state that during the sucrose enzyme bond reaction, 'Sucrose changes into glucose and fructose.' The other options describe denaturation or the action of a different enzyme (amylase) on starch, not the direct outcome of the sucrose enzyme bond reaction.

Question 5: The stomach churns food mechanically.

A. Ano

B. Ne

Explanation: The study materials explicitly state under the 'Stomach' functions that it 'Churns food mechanically'.