Answer/Explanation:
1. Isotonic solutions are those with the same concentration of solute as another - in this case of human blood cells. The two solutions are said to have the same osmotic pressure, meaning they are in an equilibrium, and nothing will happen to the red blood cells.
2. In contrast, hypertonic solutions have more solute and less water than another solution, in this case the cytoplasm of the blood cells. I.e. the solution is more concentrated than the human blood cells. Therefore, water will flow out of the cell by osmosis to try to reach an equilibrium. This means that the red blood cell will shrink and shrivel up, as water leaves the cell in to the surrounding environment