Page 8 - LN-cH-11

Osmosis is helpful in many ways as given below
(i) It helps in maintenance of cell turgidity.
(ii) Plays a vital role in stomatal movement during transpiration.
(iii) It helps in the movement of liquids across biological membranes.
(iv) It also have effects on absorption of water by roots.
Osmotic Pressure
It is that pressure of a solution, which must be applied to the solution in order to
allow passage of solvent due to osmosis. This is also the function of solute
concentration; i.e., more the concentration of a solute, greater will be the amount of
pressure applied in order to prevent water from diffusing. Osmotic pressure is
numerically equal to the osmotic or solute potential but osmotic potential has a
negative sign, while osmotic pressure is always a positive pressure.

The osmotic pressure of a solution largely depends upon the ratio between the
number of solute and solvent particles present in a given solution.
Note:
* Instrument used for measuring osmotic pressure is called osmometer, eg.,
Berkeley and Hartleys osmometer.
* Reverse osmosis is expulsion of pure water from solution through a
semipermeable membrane under the influence of external pressure, higher than OP
of solution.
Differences between Osmotic Pressure and Osmotic Potential