Transport in Plants : Plant Water Relations Test - 1

Osmosis is special type of diffusion of a liquid, when solvent moves through a semipermeable membrane from a place of higher diffusion pressure to a place of lower diffusion pressure

Materials capable of imbibition such as proteins and cellulose in living being cause seeds to swell when they are placed in water.

D.P.D. (S.P.) of cell A = O.P. – T.P. = 5 – 4 = 1 atm. 

D.P.D. (S.P.) of cell B = 3 – 1 = 2 atm 

So, movement of water is from cell A to cell B, i.e., direction of movement of water is from lower D.P.D. (S.P.) to higher D.P.D. (D.P.).

1 M solution of a solute at normal temperature and pressure has water potential –23 bars, hence 0.1 M solution will have water potential –2.3 bars.

Mimosa pudica (also called touch me not plant) is a creeping annual or perennial herb often grown for its curiosity value. The leaf of this herb droops down on touching them because of loss of water from cells to intercellular spaces in pulvinesand pulvinules.

Thistle funnel whose mouth is tied with egg membrane is the physiological experiment of osmosis. Egg membrane is a semipermeable membrane which allows all solvents but no solute to pass through them.

Water potential of cell protoplasm is equal but opposite is sign to D.P.D. Water potential of pure water is zero addition of solute in it, decreases it.

In formalin preserved Spirogyra filament, selective permeability of plasma membrane is lost and hence no effect on placing in hypertonic solution. If salt presents in higher concentration in a cell than outer side, water will enter in the cell by osmosis.