If a 300 mOsm cell 10 mOsm of which are from the membrane pe

If a 300 mOsm cell (10 mOsm of which are from the membrane permeable molecule urea) is placed into 300 mOsm solution containing no urea, what will happen to the cell? (3pts) Why exactly does the cell gain/lose/stay the same with respect to volume?

Solution

The cell will stay the same with respect to volume. Neither it will shrink nor swell as water can diffuse across plasma membranes. The water in the extracellular and intracellular fluids will come to diffusion equilibrium. Thus at equilibrium the osmomolarities are the same and changes in osmomolarities causes cell to shrink or swell.