question_answer 24)

  Following are a few definitions of osmosis. Read carefully and select the correct definition. (a) Movement of water molecules from a region of higher concentration to a region of lower concentration through a semi permeable membrane. (b) Movement of solvent molecules from its higher concentration to lower concentration. (c) Movement of solvent molecules from higher concentration to lower concentration of solution through a permeable membrane. (d) Movement of solute molecules from lower concentration to higher concentration of solution through a semi permeable membrane.

Answer:

  (a) The movement of water molecules through selectively permeable membrane along concentration gradient is called osmosis. It is the passage of water from region of high water concentration through semi permeable membrane to a region of low water concentration (only through semi permeable membrane) Unicellular freshwater organisms and most plant ceils tend to gain water through osmosis. Absorption of water by plant roots is also an example of osmosis.