A brief description - Osmotic pressure, Diffusion pressure defeciet, Turgor pressure

 

Diffusion:

• The diffusion is a passive movement of molecules from a region of higher concentration to a region of lower concentration.

• The flow of molecules is directly proportional to the difference in concentration. In case of diffusion, the movement is random and is independent of each other.

• The potential of solute particles to diffuse from its higher concentration to lower concentration is termed as Diffusion pressure [DP].

• The value of  diffusion pressure  is always greater for a pure solvent than the  solution.

• If sugar solution is made in water, then diffusion pressure is lower than that of water.

• The rate of diffusion is affected by the temperature, kinetic energy, and diffusion pressure gradient.

• The rate of diffusion is inversely proportional to density of medium, humidity, size of solute, molecular weight of solute etc.. Every solvent  has a  constant diffusion pressure. 

👌👌Remember - Pure solvent has maximum diffusion pressure. When some amount of solute is added to it, it’s diffusion pressure decreases. This deficit in diffusion pressure of the solution due to the addition of solute is termed as Diffusion pressure deficit [DPD].

Osmosis:

• Osmosis  involves the movement of water from high  concentrations to low concentrations through a semipermeable membrane. This process is termed as osmosis.

• If concentration of both mediums are equal,it is called an isotonic solution. Osmosis does not take place in isotonic solutions.

• Osmosis occurs when there is a difference in concentration between two mediums where osmosis occurs. Osmosis continues till the equilibrium is established between both mediums.

• Osmosis can be either endosmosis or exo-osmosis. During endosmosis, the movement of solvent takes place into the cells from the surrounding, and the cell becomes turgid.

• During exo-osmosis, the movement of solvent takes place towards the surrounding from the cell, and the cell becomes flaccid.

Osmotic pressure [OP]-

• The pressure that is applied on a solution to separate a pure solvent from the solution by means of a semipermeable membrane is termed as osmotic pressure [OP].

• The osmotic pressure  of pure solvent is  zero and  osmotic pressure  is always positive.

• Osmotic pressure is directly proportional to diffusion pressure deficit and concentration of solution.

Relation between Diffusion pressure deficit [DPD] Osmotic pressure [OP],Turgor Pressure [TP]

• The difference between the diffusion pressure of the pure solvent and its solution is termed as diffusion pressure deficit .

• Diffusion pressure deficit is used to determine the osmotic pressure when water enters into the plant cell from the surrounding.

• The direction of osmosis is determined by diffusion pressure deficit.

• The difference between osmotic pressure  and Turgor pressure  is known as diffusion pressure deficit.

DPD = OP-TP

• Normally, osmotic pressure  is greater than the turgor pressure.

Turgor pressure [ψp]:

• The  pressure that is generated when solvent particles enter the cell and the cell membrane pushes the cell wall is termed as turgor pressure (TP).

• Turgor pressure is onlyapplicable for osmotic solution.

• Flaccid cell has zero turgor pressure whereas the turgid cell has maximum turgor pressure.

• In case of plasmolyzed cells, turgor pressure is believed to be negative.

• Turgor pressure maintains turgidity and growth of the cell.

• It plays a vital role in germination of seed because plumule and radicle are enclosed in  sheath of monocot embryo and dicotyledons embryo, are emerged due to turgor pressure of cell.