A sample of red blood cells is placed in an isotonic solution and viewed under a microscope.

Question

There are disk-shaped red blood cells.
Next, sugar is added to the solution to create a hypertonic solution. The sample is then looked at under a microscope again.
There are shriveled red blood cells.
What happened to the red blood cells after the sugar was added to the solution?
A.
The red blood cells released water through osmosis to reach equilibrium with the surrounding solution.

B.
The red blood cells absorbed water through osmosis to reach equilibrium with the surrounding solution.

C.
The red blood cells released water through active transport to reach equilibrium with the surrounding solution.

D.
The red blood cells absorbed water through active transport to reach equilibrium with the surrounding solution.

Answer 1

The correct answer is:

A. The red blood cells released water through osmosis to reach equilibrium with the surrounding solution.

When sugar is added to the solution, it creates a hypertonic environment relative to the interior of the red blood cells. In a hypertonic solution, the concentration of solutes (in this case, sugar) is higher outside the cells than inside. As a result, water moves out of the red blood cells through the process of osmosis to balance the solute concentrations on both sides of the cell membrane. This causes the red blood cells to shrink or become shriveled.