The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. At the beginning of the U-tube experiment illustrated above, which of the following statements is true?
A) Side A is hypertonic to side B.
B) Side A is hypotonic to side B.
C) Side A is hypertonic to side B with respect to glucose.
D) Side A is hypotonic to side B with respect to NaCl.

Question

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.  At the beginning of the U-tube experiment illustrated above, which of the following statements is true?
A) Side A is hypertonic to side B. 
B) Side A is hypotonic to side B. 
C) Side A is hypertonic to side B with respect to glucose. 
D) Side A is hypotonic to side B with respect to NaCl.

Quizplus · Accepted Answer

At the beginning of the experiment, the concentration of glucose is higher in side B than in side A, making side A hypotonic to side B. The selectively permeable membrane only allows the permeation of NaCl and not glucose, making it irrelevant to the comparison of the hypertonicity or hypotonicity of the solutions based on glucose concentration. The concentration of NaCl is not relevant to the comparison of the hypertonicity or hypotonicity of the solutions based on glucose concentration.

The Solutions in the Arms of a U-Tube Are Separated