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?

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. Therefore, water molecules will diffuse from side A (hypotonic solution) to side B (hypertonic solution) to equalize the concentration of glucose. As a result, side A will become more hypotonic (lower concentration of solutes) and side B will become more hypertonic (higher concentration of solutes). This implies that the volume in side B will increase and the volume in side A will decrease.

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