MCAT Question of the Day 4/28/13: Cell Biology

Q: If a cell was placed into a isotonic solution…

A. Water would pass out through the plasma membrane faster than it goes in.

B. Water would pass in through the plasma membrane faster than it goes out.

C. The cell would swell.

D. No unequal rates would be experienced.

 

 

 

 

 

The correct answer is: (Highlight to see answer)

 

D

An isotonic solution has a very similar osmotic pressure to the cell itself thus molecules of water will enter and leave the cell at equal rates. If the question has asked hypertonic solution then the osmotic pressure would be greater outside the cell and water would leave the cell shrinking it. Similarly a hypotonic solution would swell the cell with water because the osmotic pressure would be less outside the cell.