Plant Physiology:- Diffusion, Osmosis, plasmolysis, Diffusion pressure deficit, Solutions, Imbibition
Plant physiology
PLANT PHYSIOLOGY
Plant physiology- Plant physiology is a study of vital functional activity of the plant.
1. Diffusion- Means to spread or to disperse in all direction.
• The movement of the molecule of gases, liquid and solid from the reason of higher concentration to the region of lower concentration until a equilibrium is reached among molecule through out the available space is known as diffusion.
• Example is Spreading of Scent molecule in Room.
2. Osmosis- It is a special type diffusion of liquid through a semi permeable membrane.
• It means diffusion of liquid from lower concentration of solution to higher concentration through semi permeable membrane.
• Osmosis occur only in liquids.
• Plasma/Cell membrane is a semi permeable membrane.
Example:- swelling of kishmish in water
• In a pure solvent, the value of osmotic potential is zero.
a. Endo osmosis- The solvent of lower concentration inter inside the cell is called endo Osmosis.
Example:- Raisins (kishmish) swell Exampler due to endo osmosis.
2. Exo osmosis- The output movement of solvent from higher concentration medium is called exo osmosis.
Example:- In pickle salt act as Exo Osmosis on bacterial cells and killed microbes.
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3. Plasmolysis- Plasmolysis is a shrinking of Protoplasm due to outward flow of water in a hypertonic solution.
• If a plasmolysed cell is kept in pure water the cell attend their original shape and size due to endo osmosis. This phenomenon is called de- plasmolysis.
• Example- Excessive use of fertilizer in the soil Kill the plant due to plasmolysis.
4. Diffusion pressure deficit (DPD)
• It is also called suction pressure.
• It is the force per unit area by which water enter into a cell.
DPD = OP-TP (WP)
Where,
OP- Osmotic pressure
TP- Turgor pressure
WP- Wall pressure
• When water in a cell due to swelling (outward) pressure exerted by the cell solution on a cell wall is known as turgor pressure.
• When water enter in Cell the cell exert an opposite (inward)pressure on a cell membrane is called wall pressure.
• Water potential is always negative and maximum value is zero.
5. Solutions:-
1. Hypotonic solution:- It means low concentrate solution.
2. Hypertonic solution:- Strong or higher concentrate.
3. Isotonic solution:- Neither weak nor strong solution. Example:- Eye drop.
6. Imbibitions:-
• The absorption of water by dry woody substance due to hydrophilic colloid is called imbibition.
Eg:- Absorption of water by dry Woods.
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