Q1 of 67 Page 41

Tick-mark the correct statements:

(i) Diffusion is the movement of molecules from a region of their lower concentration to that of a higher one


(ii) Osmosis includes diffusion, but not vice versa.


(iii) Osmosis is unidirectional.


(iv) Exosmosis may cause bursting of a call.


(v) Semi-permeable membrane prevents the Passage of the solute molecules.


(vi) In an experiment on osmosis, if external pressure is applied on a dilute solution, less water will pass into the concentrated solution.

(i) False

Explanation: Diffusion is the movement of molecules from a region of their higher concentration to their lower concentration.


(ii) True


Explanation: In osmosis there is diffusion of molecules through a semi-permeable membrane across the density gradient. In case of diffusion of substance no membrane separation is present.


(iii) False


Explanation: Osmosis can be of two types either inward or endosmosis or outward or exosmosis depending on the extent of concentration of the solution surrounding it.


(iv) False


Explanation: Exosmosis is the outward movement of water through the semi-permeable membrane, when the cell is placed in hypertonic solution which leads to plasmolysis.


Note:


Hypertonic solution: In this case the solution in which the cell is placed has a higher solute concentration than the solute concentration within the cell.


Plasmolysis: shrinkage of the protoplast of plant cell due to outward movement of water.


(v) True


Explanation: a semi-permeable membrane is the one which allows the passage of molecules selectively across the membrane. It allows the free passage of solvent but prevents the passage of solute molecules.


(vi) True


Explanation: If the dilute solution is compressed the molecules in it comes close as the volume decreases. This leads to its increase in density thus, the concentration increases as per volume and leads to no net passage of water into the concentrated solution.


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