A semipermeable membrane sac filled with water and large molecules of starch is suspended in a beaker of distilled water. What will happen?
A) The starch will leave and the water will enter until both sides reach equal concentrations.
B) Water will enter the sac and it will swell.
C) Because the starch cannot leave, the water cannot enter.
D) We cannot determine the outcome unless we know the tonicity of the solutions.
E) The starch will leave the sac and it will shrink.

Question

Quizplus · Accepted Answer

Due to the semipermeable membrane, only water can pass through, but not the large molecules of starch. Since the beaker contains distilled water (which is hypotonic), the water will move from an area of low solute concentration to an area of higher solute concentration (inside the sac). As a result, the sac will swell as it fills with water.

A Semipermeable Membrane Sac Filled with Water and Large Molecules