(This is the exact answer) The red blood cell shrank because water moved out of the cell, which happened because the concentration of salt outside the cell was greater than the concentration of salt inside the cell. Because the salt molecules take up space in the salt water, the concentration of water outside the cell was less than the concentration of water inside the cell. Therefore, water moved out of the cell from the area of high concentration to the area of low concentration, causing the cell to shrink.
Answer: Water moved from inside the red blood cell into the salt water.
This is because of the osmotic difference between the salt solution and the red blood cell. This means that there is difference in the solute (salt) concentration inside the red blood cell and the salt solution.
Explanation: The salt concentration in the solution is higher than the salt concentration inside the red blood cell, that is, the red blood cell has more water concentration that the salt solution, therefore there will be movement of water from the inside of the red blood cell into the salt solution thereby causing the red blood cell to reduce in size. The movement of water from the red blood cell into the salt solution is to create a balance between the water concentration in the two environments, hence the movement of water from an area of high water concentration to an area of low solvent concentration across the selectively permeable membrane of the red blood cell.
