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Difference Between Endosmosis and Exosmosis

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Last updated date: 15th Jul 2024
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An Introduction to Osmosis: Process, Mechanisms, Exosmosis and Endosmosis

Before understanding the differences between endosmosis and exosmosis, one must be aware of the process of osmosis and its mechanism. 


Definition of Osmosis

Osmosis is defined as the passage of any solvent across a membrane that is selectively permeable into a region of higher solute concentration. This process will result in an equalization of solute concentration on both sides of the membrane. Although osmosis may happen in any solvent, including supercritical liquids and certain gases, most osmosis research focuses on the movement of water within cells.  The movement of water throughout our entire body is managed by controlling solute concentrations and osmosis. The water that is absorbed or dispersed provides stability and functionality to every cell, tissue, and organ in our body.


Mechanism of Osmosis

The basic principle of osmosis is the difference in chemical potential between two components that are separated by a semipermeable membrane. The free energy that is accessible per mole of material in a solution is known as chemical potential. The pure solvent has higher energy in the osmosis demonstration compared to the solution, which has lower energy (i.e., lower chemical potential), creating a gradient to allow the pure solvent to enter Chamber. The cytoplasmic solute, which is involved in energy metabolism and dynamically replenishes chemical molecules, is the source of the potential difference.

What is Endosmosis and Exosmosis?

Endosmosis

Water diffuses from the cell's outside to its inside, or cytoplasm, through endosmosis. If you retain a cell in the hypotonic solution, you can study endosmosis.


A greater solute concentration is present inside hypotonic solution cells compared to outside. But according to the osmotic principle, only water may get through the selective barrier, not solutes. As a result, a selective barrier will let the water from the area around the cell where it is highly concentrated to enter the cytoplasm. Endosmosis causes the cell to enlarge, become turgid, or even explode.


Conditions for Endosmosis

The concentration of the solute and solvent within and outside the cell during endosmosis is as follows:


  • The concentration of solvent is higher and that of solute is lower outside the cell than within.

  • In comparison to the cell's surroundings, the cytoplasm has higher solute and lower solvent concentrations.


Exosmosis 

Exosmosis refers to an osmosis type in which the direction of the water or solvent is away from a vessel or cell. It occurs when there is a difference between the water potential within and outside of the cells. As a result, the concentration of the solute in the solution surrounding the cell is higher than the concentration of the same solute in the cytoplasm. Exocytosis is the process by which water molecules leave the cell through the semipermeable cell membrane. As a result, the cells contract and plasmolysis occurs.


Conditions for Exosmosis

The concentration of the solute and solvent within and outside the cell during endosmosis is as follows:


  • The concentration of solvent is lower and that of solute is higher outside the cell than within.

  • In comparison to the cell's surroundings, the cytoplasm has lower solute and higher solvent concentrations.


Endosmosis and Exosmosis Difference 

S.No

Exosmosis

Endosmosis


The movement of solvent outside the cell.

(Exo- outside)

The movement of solvent inside the cell.

(Endo- inside)


Osmosis takes place outside a cell.

Osmosis takes place inside a cell.


Osmotic pressure is high.

Osmotic pressure is low.


Exosmosis causes the cell to shrink.

Exosmosis causes the cell to swell.


Water travels from the cytoplasm of the cell, which contains comparatively less solute, into the surrounding solution, which contains relatively more solute.

Water travels from the surrounding solution, which has comparatively fewer solutes, into the cell, whose cytoplasm contains relatively more solutes.


For example- Pickles' salt addition aids in their preservation by plasmolysis of bacteria to kill off their cells.

For example- Plants use endosmosis to draw water from the surrounding soil into their root hair cells. 


Summary

Endosmosis and exosmosis are the two types of osmosis. The main distinction between the two processes is that exosmosis involves the removal of water from the cell, whereas endosmosis involves the transport of water within the cell. We must discuss the ideas of hypertonic, hypotonic, and isotonic solutions in this regard. A solution is said to be hypertonic to the cell if it contains a solute concentration higher than that of the cell, and hypotonic to the cell if a low solute concentration is present. If the solute concentration in the solvent and the cell sap are the same, the two are said to be isotonic.

FAQs on Difference Between Endosmosis and Exosmosis

1. What are the Characteristics of Endosmosis?

Endosmosis is the mechanism through which water enters the cell. Cells introduced in hypotonic solutions cause endosmosis. Endosmosis, which happens when the concentration of a solute outside a cell is lower than that of a solute inside a cell, is what causes this to happen. The water potential of the environment is higher than the water potential of the cytosol during endosmosis which causes the entry of water molecules inside the cell.

2. What are the Characteristics of Exosmosis?

Exosmosis is the term used to describe the osmosis of a cell or vessel toward the outside. It happens when the inner water potential of the cell is higher than the water potential of its surroundings. Hypertonic solutions, which are the most prevalent type of solution, are those in which the solute concentration in the surrounding solution is higher than that in the cytoplasm. Water molecules cross the cell membrane and leave the cell through the exosmosis process.

3. What is the Major Difference Between Endosmosis and Exosmosis?

Water moves through cell membranes through two different forms of osmosis: endosmosis and exosmosis. When cells are put in a hypotonic solution, endosmosis is the process by which water enters the cell, and exosmosis is the process by which water exits the cell. The direction of the water's travel in each step determines the primary distinction between endosmosis and exosmosis. Thus, endosmosis results in swelling of the cells whereas exosmosis results in the shrinking of the cell.