Question

What is osmotic pressure? Explain the term “osmosis”.

Answer 1

Hint: Flow of solvent molecules takes place due to difference in concentration. Sometimes solvent molecules pass from a region of lower concentration to higher concentration which is separated by a semipermeable membrane i.e. from higher water concentration to lower water concentration. This is the process that is explained in the answer.

Complete step by step solution:
- Osmotic pressure refers to the minimum amount of pressure that is needed to be applied on the higher concentration region to stop the inflow of solvent molecules from the region of lower concentration through a semipermeable membrane(partially-permeable membrane).
- Osmosis is a passive process of transfer of solvent molecules from a hypotonic solution to a hypertonic solution through a semipermeable membrane. No energy is required to transfer the solution.

Osmosis is of two types:
1) Endosmosis– When a substance is placed in a hypotonic solution, the solvent molecules move to the inside of the cell and the cell becomes turgid or undergoes deplasmolysis. This is known as endosmosis.
2) Exosmosis– When a substance is placed in a hypertonic solution, the solvent molecules move from outside of the cell and the cell becomes flaccid or undergoes plasmolysis. This is known as exosmosis.

Note: Osmosis influences the transport of nutrients and the release of the metabolic waste products. It is responsible for the absorption of water from soil and conducting it to upper parts of the plant through the xylem. It helps in sustaining life of a cell by maintaining water and intercellular fluid levels. It maintains the turgidity of cells. It is a process by which plants maintain their water content despite the constant loss of water due to transpiration.