An Explanation - Plasmolysis and Imbibition

 PLASMOLYSIS

• Plasmolysis refers to the  shrinkage of a plant cell due to the  contraction of the protoplasm.

• This shrinkage occurs when there is a loss of water from the cell. Osmosis is the main reason that causes plasmolysis of cells.

• A process of plasmolysis can be observed  in the laboratory.

• When a  living  plant cell is kept in a salt solution or sugar solution.

• Water is moved from the plant  cell to sugar or salt solution. As a result plant cells are flaccid or shrinkage.

• When an experiment regarding the plasmolysis is conducted in the laboratory,  the Tradescantia plant epidermal cell is frequently used.

• Plant cell has a cell membrane followed by the cell wall. 

• Cell membrane  that makes aloof internal content of a cell from the surrounding environment. Cell membrane is semipermeable in nature.

• The semipermeable membrane allows water passively without expenditure of energy.

• It also  allows some particles, ions etc but , it does not permit other material .

• But Water molecules constantly move inside and outside the cell across the cell membrane without any hindrance. This free flow of water causes it to absorb water.

• When a plant cell is kept in concentrated salt solution or sugar solution or hypertonic solution,  water is moved  from  inside the cell  to outside medium of sugar or salt solution. This is called exosmosis.

• Exosmosis is the movement  of water from higher  concentration to lower concentration through a semipermeable membrane.

• Water is moved  from the plant cell to the surrounding medium if the plant cell is kept  in a sugar solution or salt solution. This is because water concentration inside the cell is greater than outside the cell.

• Therefore, water moves through the cell membrane into the surrounding medium.

• As a Result, plant cells shrink due to the contraction of protoplasm.The shrinkage of plant cells in hypertonic solution  due to contraction of protoplasm is called plasmolysis.

• The initial stage of plasmolysis where the protoplasm just starts leaving the cell wall is called incipient plasmolysis.

• When a plasmolysed cell is placed in a hypotonic solution, the water is  moved into the cell because of the higher concentration of water outside the cell In comparison to inside the cell. This is called endoosmosis.

• As a result,  The cell starts to swell and the cell becomes turgid. It is called deplasmolysis.

Significance of Plasmolysis

• It reveals facts  to understand the living nature of a cell. It  helps to preserve meat, jellies and pickles.

• It also determines the permeability of the cell wall and the selectively permeable nature of the plasma membrane.

           

     IMBIBITION

• The absorption of water by the solid particles without forming a solution is called imbibition.

• On the other hand,the adsorption of water by hydrophilic colloids is known as Imbibition. 

• The Solid materials that are involved  in imbibition are called Imbibants. The liquid which is imbibed is known as Imbibate.

• For example - A piece of wood is swollen due to the entry of water. In this case, wood is Imbibants and the water is Imbibate. 

• Due to imbibition of water, the volume of water is increased in solid materials. As a result, pressure is created known as Imbibitional Pressure.

if imbibition occurs-

• A water potential is created between imbibant (wood) and imbibe(water). 

• There should be some force of attraction between imbibant and imbibed liquid. There is  increase in Volume of the solid material.

Imbibing Capacity:

• The Imbibing capacity is varies in different solid materials. 

• For example - Hydrophilic colloids have maximum imbibing capacity. Protein has maximum amount of imbibition in compare to   starch and cellulose.

• That is the reason seed containing protein more swell than cellulose and starch containg seeds. 

• Constitution of solid material,  Temperature, Pressure and  pH of the medium etc are prominent factors that affect the rate of imbibition.

Significance of Imbibition

• It keep the cells moist and in seed germination, growth of seedling through the soil, ascent of sap in plants, etc.