Diffusion

The process of movement of molecules, ions, gases, solutes from their higher concentration to lower concentration is called diffusion. Ex. If a bottle of perfume is opened in a closed room the perfume spread by diffusion.


Expermint of Diffusion

When a crystal of Copper sulphate is placed in beaker containing water, a dense blue colour is seen around the crystal. It decrease with increase in distance from the crystal representating the diffusion of copper sulphate molecules in water. Here, the CuSO₄ mol. move towards CuSO₄ finally the mole of both water and CuO₄ are distributed equally throughout the solution.

Diffusion Pressure :-

The pressure developed by the diffuring particles from the area of higher to lower concentration is called diffusion pressure

Singificance of Diffusion pressure

  1. It helps in the exchange of gas during respiration & photosynthesis
  2. It also help in exchange of gases during transpiration
  3. Passive absorpation of minerals takes place by diffusion.
  4. IT help in pollination because insects are attracted towards plant due to diffusion of aroma of flower
  5. It help in distrubation of substance in the protoplasm

Osmosis

The process of movement of water or solvent from their higher concentration to lower concentration through semi-permiable membrane is called osmosis.

Types of osmosis :-

1. Endosmois

When a living cell placed inside hypotonic solution, water enters inside the cell and cell be come turgid is called and Endosmosis.

2. Exomosis

The outward movement of water from a cell when it is placed in hypertonic solution is called Exosmosis. By this process cell becomes flucid.

Types of solution :-
1. Hypotonic

It is the solution in which the concentration of solute is lower then the concentration of solvent.

2. Hypertonis

It is the solution in which the. Concentration of solute is Concentration of solvent.

3. Isotonic

In this type the concentration of both solute and solvent are equal

Experiment :- To demonstrate the osmosis by using photo Osmascope

Apparatus :-

A large sized potato,sugar solution petridiscs and two pins.

Procedure :-

Peel off the skin of large sized potato with knife and cut its one end to make flat base.Make a hole or cavity in the potato by using knife and fill the sugar solution in to the cavity nd make the initial level.The whole apparatus?potato placed inside a petridiscs conting water and leave it about few hours

Result :-

After sometime the level of sugar solution in the cavity raise up this is because of movement of water through higher concentration to lower concentration.Thish is called Osmosis .

Singificance of Diffusion pressure

  1. Osmosis help in growth of tissue
  2. It also help in opening & closing of stomata
  3. The roots of plant absorb water by osmosis.
  4. Cell to cell movement of water in the plant occurs by osmosis
  5. It help in movement to plants parts like leaf of Namaste(Mimosa plant or touch me not plant).
  6. Osmosis help to control the desiscence of anther to foods,etc.

Plasmolysis

The process of shrinkage of protoplasma of plant cell due to loss of water when it is placed inside hypertonic solution. The process is called plasmolysis and cell is called plasmolyred cell

Deplasmolysis

When a plasmolysed cell placed inside hypertonic solution water enters into the cell and cell become turgid. The process is called Deplasmolysis

Singificance of plasmolysis

  1. Plasmolysis is the phenomenon of living cell. Dead cell cannot show plasmolysis.
  2. It indicates the semi-permiable nature of Plasma membrane.
  3. It is used to determine the osmotic pressure of cell sap
  4. It checks the growth of bacteria and fungi in jam,jerry,etc as bacteria and fungi are plasmolysed in conc. sugar solution

Imbibition

The process of increase in volume or diameter of a solid is called imbibition. substance by seaking water is called imbibition. Eg:- Swelling of door and windows in Winter Season, swelling of seeds/gum/etc.

Singificance of Imbibition

  1. It help in germination of seed because the stored food in seed swell causing the seed pore rupture.
  2. Before absorption of water the wall of root hair swells by imbib water.
  3. Brusting of pollen grains ins inside the ovary through Imbibition
  4. Wooden door and windows are jame of during rainy season due to osmosis.
  5. The ripping of fruits takes place by imbibition

Osmotic relation of the cell

Living cell consists of plasma membrane and cell sap. Plasma membrane is really not a semi-permiable membrane and it allow to pass across it small amount of solute also so it is called selective permlable membrane When a living cell placed in water on hyper-tonic solution water enters the cell sap by endasmas As a result of entry of water into the cell sap a pressure develops inside the protoplasm against the cell wall And cell became turgid thes pressure as called turger pressure.
To balance the turger pressure the cell also exert a pressure, the pressure exerted by the cell wall against the expand protoplasm is called wall pressure.

Diffusion pressure Deficit(DPD)

The amount of solute by which the diffusion pressure of a solution is lowered than the pure solvent or water is called diffusnion pressure deficit(DPD). Diffusion pressure of a Jolvent of maximum As the solute is added the diffusion pressure of a solution is decreased. If the DPD of greater the cell try to absorb water. In other word, it can be said that DPD as the index of water sucking ability of a cell. So it is called suction. pressure. Suction pressure is defined as the force per unit area with which water enter in a cell. The term DPD wasw given by Bs Mayer in 1958.
DPD=OP-TP(osmatic press)
DPD=OP-O
DPD=O(OP-TP)[cell is turgid]

TP=WP=0[cell turgid]
TP>WP[cell brust ]
WP>TP [CELL Flaceid]

Osmotic pressure

The pressure required to stop the net movement of pure water into a solution through plasma membrane is called osmotic pressure. It is measured by atmosphere. The measure ment fools name asmometer. The movement of solvent from their higher concentration or lower osmotis pressure to tower Concentration of higher osmotic pressure takes place in the process of osmosis. The osmotic pressure of pure water is zero.

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