As already stated, because the solute concentration within the cell, like those of sodium and potassium ions, Na+ and K+, and many other ions, are greater, water will readily pass through the semipermeable membrane. read more
If red blood cells are placed in pure water, water enters into the red blood cells by osmosis and the red blood cells swell up and burst. If red blood cells are placed in a concentrated solution, water leaves red blood cells by osmosis and they are unable to function. read more