how does the amount of substance …

The movement of water molecules through a selectively permeable membrane is called osmosis. It is affected by the amount of substance dissolved in water. Thus, osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. If we put an animal cell or a plant cell into a solution of sugar or salt in water then three things could happen:

(i) When eukaryotic cells are placed in hypotonic solutions, the water molecules will enter into the cell and the cell will swell up.

(ii) If eukaryotic cells are placed in hypertonic solutions, the water molecules will come out of the cell and the cell with shrink.

(iii) If the eukaryotic cell is placed in isotonic solution, the amount of water molecule will remain the same; it will neither move out or will go inside. The cell will remain same sized.