The diagram shows an apparatus set up to investigate the effect of changing the concentration of glucose in the surrounding solution on the movement of molecules through a selectively permeable membrane (Visking tubing) in 15 minutes. As the concentration of glucose solution in the surrounding solution increases, which of the following statements are correct? Net diffusion of water increases. Glucose molecules reach an equilibrium quicker. There is less change in the volume of the surrounding solution. Net diffusion of glucose increases.

Explanation

Looking at the diagram, it is apparent that increasing glucose concentration in the surrounding tube will decrease the difference in the concentration of glucose between the surrounding liquid and inside the visking tubing. As there is less concentration gradient, the net diffusion of water would decrease so statement I is incorrect. The time to reach equilibrium would decrease as there is less difference in concentration of glucose, so statement II is correct. As the concentration gradient is less, less net movement of water would be needed to reach equilibrium, so volume would also change less, hence statement III is correct. There is no movement of glucose molecules, so statement IV is incorrect.