The pressure that is exerted on the cell wall duel to turgidity is called Turgor pressure (T.P.) It is defined as the amount of pressure inside a cell solely due to its water content, whereas Osmotic Pressure is defined as the pressure required to stop osmotic flow between the cell and a pure solvent when the pressure exerted by water is zero.
- This pressure is exerted on the cell wall due to the entry of water inside the cell.
- The turgor pressure is responsible for the growth and enlargement of the cell. It also keeps the stem erect and leaves expanded.
- This pressure is exerted by the protoplast against the cell wall due to the entry of water is called as pressure potential.
The water pressure inside plant cells is called turgor pressure, and it is maintained by a process called osmosis. Technically speaking, osmosis is the movement of water across a differentially permeable membrane from a place where water concentration is higher to one where the concentration is lower.
Wall pressure (W.P.): The cell wall, when stretched fully (due to turgidity), also exerts a counter-pressure on the fluid contents of the cell is said to be the wall pressure. In turgid condition the turgor pressure equal to the wall pressure. Wall pressure is the pressure applied to the cell wall on the contents of the cell. The pressure exerted on the contents of a plant cell by the cell wall that is equal in force and opposite in direction to the turgor pressure.
- This process occurs in plants, bacteria, fungi and protists to contain cell walls.
- The endosmosis ceases when the turgor pressure becomes equal to the wall pressure.