Plant Cells: Osmosis and Plasmolysis

The biological phenomenon happens all around us in our everyday life. Have you ever wondered how a raisin swells when kept in a glass of water? No right? It happens due to a biological phenomenon named osmosis. In the same way, you must have drank water while feeling thirsty. The same background process occurs behind this too.

In Biology, osmosis happens due to the movement of water molecules from a highly concentrated solution to a low concentrated solution via a semi-permeable membrane. On the other hand, plasmolysis is a process of shrinkage of cell cytoplasm due to water loss from the plant cell. Do you want to know how these processes are occurring? Keep reading to learn more.

Definition:
Plasmolysis is the procedure of cytoplasm shrinkage due to water loss from the cell. It happens when plant cells are immersed in a hypertonic solution.
Osmosis is the movement of water molecules via plant cells from a higher concentrated solvent solution to a lesser concentrated one. The process takes place with the help of a semi-permeable membrane.

Osmosis and Plasmolysis: Overview

The key difference between osmosis and plasmolysis is that osmosis is the movement of water molecules from high water potential to a lower water potential through a semi-permeable membrane whereas plasmolysis is the shrinkage of a cell due to the persisting movement of the water molecules out of the cell.

Let us look into details of the two processes:

Characteristics	Osmosis	Plasmolysis
Definition	It is a passive diffusion process where water movement occurs via a plasma membrane in a plant cell.	It is the water loss across the cells when they are kept in a hypertonic solution.
Gradient	A potential gradient exists across the plasma membrane along the lining of the plant cells.	There is consistent water movement that continues across the cell
Types	The process is of two types: endosmosis and exosmosis	Concave plasmolysis and convex plasmolysis are the two types of plasmolysis.
Solution Types	The process occurs in hypertonic, hypotonic, and isotonic solutions.	The process occurs in extreme hypertonic solutions.
Real-life Examples	Seed dispersal by water	Shrinkage of vegetables when kept in saline water

Now that you have known the basic differences between Osmosis and Plasmolysis, let us have a look into the similarities between osmosis and plasmolysis:

Similarities Between Osmosis and Plasmolysis

Following are some of the similarities highlighted between the two processes:

Both the processes take place in a plant cell.
Water tonicity or gradient generation is the background cause behind these processes.
In both osmosis and plasmolysis, water movement happens across the plasma membrane.

Importance of Osmosis and Plasmolysis

Osmosis maintains the turgidity of a cell. Osmosis is the sole phenomenon for which the water content of the cells remains maintained in spite of the constant water loss which happens due to transpiration/ plant evaporation. In other words, it maintains the cellular diffusion of plant cells. Maintenance of cell turgor pressure also gets under control along with the movement of plant parts.

Plant cells are not known to tolerate prolonged exposure to a medium when there is more concentration than their own cells. Plasmolysis occurs when there is a build-up of the extreme hypertonic solution. The plant cells can be quickly maintained in the turgor condition simply by keeping it in a water medium dilution. However, you should keep in mind that plasmolysis sometimes disrupts the normal water balance and it enhances the overall functioning of the plant when it comes to the water supply.

Loss of water happens when a plant cell containing a cell wall is kept in a hot/dry weather condition. Induction of the cell membrane collapses inside the cell wall resulting in gaps between the cell wall and cell membrane and lysis occurs as the cell shrivels and dies.

Questions on Osmosis and Plasmolysis

Now that you have understood the main points of concern regarding Osmosis and Plasmolysis, let us look at some of the questions which can appear in your exam:

What is plasmolysis?

A. The process of water flowing out of cells in a hypertonic solution
B. Complete procedure of water flowing in cells in a hypotonic solution
C. Water flowing in and out of cells at an equal rate in an isotonic solution
D. The process of water flowing out of cells in a hypotonic solution

2. Why can gargling with salt water help cure a bacterial infection?

A. The creation of a hypertonic environment due to the presence of salt, causes bacteria to undergo plasmolysis and die.
B. Hypotonic environment, causing bacteria to undergo plasmolysis and die.
C. The salt creates a hypertonic environment, causing bacteria to swell with water and burst.
D. The salt creates an isotonic environment, where bacteria can no longer control the flow of water into or out of the cell.

3. Osmosis is a special kind of_________

A. Regulation
B. Absorption
C. Diffusion
D. Adsorption

4. Root hairs absorb water from soil through______________

A. turgor pressure
B. ion exchange
C. osmosis
D. DPD

5. Passage of water across a selectively permeable membrane is_____________

A. osmosis
B. active transport
C. facilitated diffusion
D. pinocytosis

6. In the process of plasmolysis occurs___________

A. endosmosis
B. exosmosis
C. imbibition
D. diffusion

We hope that this comprehensive article on ‘Plant Cells: Osmosis and Plasmolysis‘ has been assistive and provided you with insights into the daily life examples of such biological phenomena inside the plant cells.

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