Absorbance at Various pH Levels

The table represents the results of an experiment where the effects of pH buffers on an enzyme found in saliva (amylase) were studied. A spectrophotometer set at 500 nm was used to measure absorbance at the various pH levels every 20 seconds for 2 minutes. The higher absorbance values would indicate greater enzyme activity. All experiments were conducted at the same temperature.
Which statement correctly identifies the result that the optimum pH for amylase function is 7?
A) The pH with the lowest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein.
B) The pH with the highest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein.
C) At pH 9, the enzyme is denatured and will lose its function, but not its structure.
D) At pH 4, the structure of the enzyme will be altered, and the enzyme would not be able to catalyse the reaction.

Question

Absorbance at Various pH Levels

The table represents the results of an experiment where the effects of pH buffers on an enzyme found in saliva (amylase) were studied. A spectrophotometer set at 500 nm was used to measure absorbance at the various pH levels every 20 seconds for 2 minutes. The higher absorbance values would indicate greater enzyme activity. All experiments were conducted at the same temperature.
Which statement correctly identifies the result that the optimum pH for amylase function is 7?
A) The pH with the lowest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein. 
B) The pH with the highest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein. 
C) At pH 9, the enzyme is denatured and will lose its function, but not its structure. 
D) At pH 4, the structure of the enzyme will be altered, and the enzyme would not be able to catalyse the reaction.

Quizplus · Accepted Answer

The table shows that the pH with the highest absorbance value (0.445) is pH 7, which indicates the highest enzyme activity. Therefore, the optimum pH for amylase function is 7. Option A is incorrect because the pH with the lowest absorbance values is pH 9, which shows that the enzyme is denatured and has lost its function. Option C correctly identifies that the enzyme is denatured at pH 9, but it does affect the function of the enzyme, making this option incorrect. Option D correctly identifies that the structure of the enzyme is altered at pH 4, but it does not specify whether the enzyme is able to catalyse the reaction, making this option incomplete.

Absorbance at Various PH Levels