Answer:
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in a hypertonic sucrose solution.
Explanation:
As the plasma membrane of RBCs allows water and urea to pass through but doesn't allow the sucrose to enter , when the RBC's are placed in hypertonic sucrose solution ( a solution which contains excessive amount of sucrose in relation to water ) the water from the RBC's will move outside towards the hypertonic sucrose solution because the RBC's are relatively hypotonic as compared to the hypertonic sucrose solution along the concentration gradient ( From hypotonic to hypertonic ) and the sucrose cannot enter the RBC's as the plasma membrane of RBC's don't allow.
As the water is lost from the RBC's they start to shrink.
