A red blood cell is placed into an aqueous solution. The red blood cell has a lower concentration of protein and sugar than the aqueous solution,...

In this situation, two solutions are present on either side of a semipermeable membrane. The two solutions are the cell interior and the liquid the cell is placed in. The semipermeable membrane is the cell membrane. The concentrations of sugar and protein in the two solutions are different.

In this situation, osmosis will occur. Osmosis is the movement of water in response to a concentration gradient (difference). Osmosis will occur through a membrane as long as the concentrations are not equal. Water will move from a region of high water (low solute) concentration to a region of low water (high solute) concentration.

In this example, the interior of the cell is high water (low solute) compared to the external environment. So water will move by osmosis through the cell membrane and into the outer environment. The red blood cell will thus shrink in volume.