The Fundamental Unit of Life – Diffusion & Osmosis (Part -2)

Diffusion

• Diffusion is defined as the movement of particles from a region of high concentration to a region of low concentration.

Osmosis

• Osmosis is defined as the passage of water from a region of high water concentration to a region of low concentration through a Semi-permeable membrane.
• Ex-osmosis : The passage(exit) of water from inside to outside of a cell. E.g.:- Tender Mango Shrinks when put in Salt Solution.

• End-osmosis : The passage (entry) of water from outside to inside of a cell. E.g.:- Raisins swells when dropped in Water.

Hyper-tonic Solution  (EXOSMOSIS)

• A solution that has Less  concentration of water as compared to the cell placed in it.
• The water from the cells exits to the solution, due to Ex-osmosis, and therefore thecell shrinks.

Hypo-tonic Solution (ENDOSMOSIS)

• A solution that has More concentration of water as compared to the cell placed in it.
• The water enters the cell from the solution, due to End-osmosis,  and therefore the cell swells.

Isotonic Solution (No net Osmosis)

• A solution that has Same concentration of water as compared to the cell placed in it.
• Since there is not net movement of water (osmosis) across the cell, no change in shape is observed.

Plasmolysis (HYPERTONIC)

• The detachment of cell membrane of the plant cell from the cell wall when put in Hypertonic solution is known as Plasmolysis.
• A Cell that has undergone Plasmolysis is called Plasmolysed Cell.
• Plasmolysis happens only in Plant Cells (i.e. cells having cell wall).

Turger Pressure : The pressure excreted by the cell membrane on to the cell wall, when it wants to take in water is known as Turger Pressure.

Wall Pressure : The pressure excreted  by  the cell wall on to the cell membrane is known as Wall Pressure.

Endocytosis: The process by which the cell engulfs food and other materials from its external surroundings is called endocytosis.