Is Osmosis Diffusion? 11 Facts You Should Know 


This article will help in discussing the idea that “is osmosis diffusion” and the ways osmosis can be established as a part of diffusion. 

Osmosis is described as the movement associated with water molecules from a high concentration solution to a lower concentration solution through a semipermeable membrane within the cells. 

How is osmosis diffusion?

Diffusion is defined as the movement of various molecules across a semipermeable membrane from its higher concentration to its lower concentration. Osmosis is considered to be a specific type of diffusion where only water molecules or few other solvent is considered for the movement. 

In osmosis, there is passage of water molecules or few solvent across the semipermeable membrane from the low water concentration region to higher water concentration region. 

Osmosis and diffusion similarities

Both osmosis and diffusion are termed to be related processes as they display few similar properties. Both the processes work on equalising the concentration of the two involved solutions, where particles tend to move from a higher concentration to the lower concentration.

Both osmosis and diffusion are termed to be categorised under the broad process of passive transport as both do not require any form of extra energy in order to facilitate the activity. 

Osmosis vs diffusion

The differences between the two related processes are as follows: 

OsmosisDiffusion 
The medium is limited only till liquid. The medium can be liquid, gases and solids. 
Semipermeable membrane is an important requirement. Semipermeable membrane is not an important requirement. 
Depends on the number of solutes present within the solvent.Depends on the number of other particles. 
Water requirement is there for solute movement. Water requirement is not mandatory for the movement of the particles.
Diffusion is restricted to only solute molecules. Diffusion occurs in solute molecules as well as solvent molecules. 
One-directional flow is established. All-directional flow is established.
Additional pressure is required in order to stop the flow or reverse the pressure. Process cannot be stopped or reversed. 
Similar types of solutions are needed to facilitate the process. Similar and dissimilar types of solutions are needed to facilitate the process
The solvent concentration does not equalise on both the sides of the solution. The concentration of the diffusing particles equalise on both the sides of the space.
Dependent on the solute potential. Independent on the solute potential. 
It is not associated with the uptake of any minerals or any nutrients. It is associated with the uptake of any minerals or any nutrients.

What type of diffusion is osmosis?

Osmosis is categorised mostly under the simple diffusion, where water molecules tend to pass from a higher range of concentrated area to a lower range of concentrated area through the semipermeable membrane. 

is osmosis diffusion
Diffusion across plasma membrane from Wikimedia

Is osmosis facilitated diffusion?

In most cases, it is noticed that osmosis can occur unassisted within the cells where the water molecules can pass through the phospholipid layer easily but there are cases of osmosis involving facilitated diffusion where the water molecules are transported across the membrane using aquaporins. 

Some of the aquaporins only engage in transporting water molecules across the semipermeable membrane of the cells, but some co-transport other molecules with water like glucose, urea, ammonia, carbon dioxide or ions. Aquaporins are carrier proteins that are allosterically regulated to meet the specific water balance requirements by the cells. 

Osmosis and facilitated diffusion similarities

One prime similarity between osmosis and facilitated diffusion are that both fall under the passive transport category as both do not require any form of extra energy in order to facilitate the activity. Also, both are involved in moving ions or molecules from one place to the other to facilitate physiological processes. 

Osmosis vs facilitated diffusion

The differences between the osmosis and facilitated diffusion are as follows: 

Factors Osmosis Facilitated Diffusion
Molecule typesMovement of only water molecules is initiated. Movement of various insoluble compounds like amino acids, ions, sugars and more are initiated. 
Concentration gradientMolecules are passed down the concentration gradient which is from lower gradient to higher gradient of concentration.Molecules move from a higher gradient to lower gradient of concentration. 
Membrane present Semipermeable membrane is important in order to create the concentration gradient. Requirement of the membrane is not mandatory, can occur in the absence of the membrane as well. 
Requirement of carriers. Requirement of the carriers is not mandatory, and can occur in the absence of the carriers as well.Requirement of the membrane is mandatory and cannot occur in the absence of the carriers.
Water molecules Water requirement is there for solute movement. Water requirement is not mandatory for the movement of the particles.
Occurrence The medium surrounding the cells would need to have lower concentration of the water molecules than within the cells. The medium surrounding the cells would need to have higher concentration of the molecules than within the cells. 

Is osmosis simple diffusion?

Osmosis is mostly considered under the category of simple diffusion, as the water molecules engage in passing from a higher range of concentrated area to a lower range of concentrated area through the semipermeable membrane without utilising any form of external energy. 

Osmosis and simple diffusion similarities

Both osmosis and simple diffusion processes engage in moving ions or molecules from one place to the other to facilitate physiological processes. Also, both the processes fall under the passive transport category as both do not require any form of extra energy in order to facilitate the activities. 

Osmosis vs simple diffusion

One basic difference between the two processes is that, Water requirement is there for solute movement in osmosis whereas water requirement is not mandatory for the movement of the particles in simple diffusion. 

Next, a semipermeable membrane is an important requirement for osmosis but not for simple diffusion. Also, simple diffusion can occur in mediums like gases, liquids and solids but osmosis is restricted to only liquids.  

Is osmosis bulk transport? 

Osmosis is not considered to be under the category of bulk transport, as it is categorised under passive transport. Bulk transport is the process which engages the movement of macromolecules which would include polysaccharides or proteins into as well as out of the cells. Bulk transport is mostly of two types, exocytosis and endocytosis. 

Conclusion 

In conclusion, it can be stated that osmosis is an important physiological process which is a specialised simple diffusion and is largely categorised under passive transport. 

Sayantani Misra

Hi, I am Sayantani Mishra, a science enthusiast trying to cope with the pace of scientific developments with a master’s degree in Biotechnology. Let's connect through LinkedIn-https://www.linkedin.com/mwlite/in/sayantani-misra-a54a83200

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