question_answer 20)

  A cell will swell up if (a) the concentration of water molecules in the cell is higher than the concentration of water molecules in surrounding medium (b) the concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell (c) the concentration of water molecules is same in the cell and in the surrounding medium (d) concentration of water molecules does not matter

Answer:

  (b) Osmosis is a spontaneous process where movement of solvent molecules occurs into a region of higher solute concentration from lower solute concentration through a partially permeable membrane, so as to tend to equalize the solute concentration on the two sides. When movement of the solvent takes place from outside to inside the all (inward movement) the process is endosmosis. It occurs in hypotonic solution and causes the swelling of cell.   When the movement of solvent takes place from inside to outside of the cell (outward movement) the process is exosmosis. It occurs in hypertonic solution. It results the shrinkage of the cell. When the concentration of water both in the surrounding medium and in the cell is same, the solution in the surrounding medium is said to be Isotonic and no movement of water molecule takes place.