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40 Difference Between Diffusion and Osmosis

Diffusion and Osmosis

Diffusion and osmosis are both basic biological procedures in which molecules or materials flow through cell membranes. They perform critical roles in cellular homeostasis and are required for a variety of physiological processes in living organisms.


Diffusion is a physical process that occurs when particles, such as molecules or ions, travel from a high concentration area to a low concentration area. This movement happens on its own and is caused by particles’ natural urge to spread out and become uniformly dispersed within a particular space. Diffusion is a passive process that requires no energy to operate.

The concentration gradient, or the differential in concentration of a material between two locations, is the driving force behind diffusion. There are more particles accessible to randomly travel, collide, and spread out in locations where a chemical concentration is higher. As particles move at random, they gradually disperse themselves in such a way that an even concentration is achieved over the available space. 

Diffusion is a fundamental process that occurs at numerous stages in daily existence, from the molecular level to larger scales. Diffusion can be seen in the spread of food aromas throughout a room, the mixing of two different liquids, and the exchange of oxygen and carbon dioxide between the lungs and bloodstream during respiration.


Osmosis is a sort of diffusion that occurs when water atoms travel through a semipermeable membrane. A semipermeable membrane permits certain substances, such as water, to pass through while preventing the passage of others. Osmosis occurs when the concentration of solutes (substances dissolved in the solvent, usually water) on each side of the membrane differs. In an attempt to equalise the solute concentration on both sides of the membrane, water travels from a lower solute concentration area to a higher solute concentration area.

At one stage osmosis results in the formation of an equilibrium in which the concentration of water molecules on both sides of the membrane is the same. Water particles continue to travel in both directions across the membrane at this moment, but there is no net movement of water, and the overall water concentration remains constant.

Also Read: Agglutination vs Precipitation- 20 Differences

Here are 40 differences between diffusion and osmosis:







Movement of particles from an area of higher concentration to lower concentration

Movement of solvent (usually water) from an area of lower solute concentration to higher solute concentration through a semi-permeable membrane


Type of Substances

Involves the movement of solute particles

Primarily involves the movement of solvent molecules


Driving Force

Driven by concentration gradients

Driven by differences in solute concentration


Membrane Requirement

Can occur in the absence of a membrane

Requires a semi-permeable membrane



Occurs in all directions

Typically involves solvent moving into the more concentrated solution



Generally faster than osmosis

Generally slower than diffusion


Affected by Temperature

Affected by temperature (increased temperature speeds up diffusion)

Affected by temperature (increased temperature speeds up osmosis)



Perfume spreading in a room, sugar dissolving in water

Water moving into or out of plant cells, red blood cells in hypertonic solutions


Importance in Biology

Essential for various cellular processes

Crucial for maintaining cell turgidity and proper functioning


Particles Moved

Any type of solute particles (e.g., ions, molecules)

Primarily involves water molecules


Facilitated by

Facilitated by a concentration gradient

Facilitated by a difference in solute concentration


Net Movement

Can result in a net movement in any direction

Generally results in a net movement of water into the more concentrated solution


Reverse Process

Can involve reverse diffusion

Osmosis in reverse can occur (reverse osmosis)


Size of Particles

Can involve particles of various sizes

Primarily involves smaller water molecules


Impact on Solutions

Tends to equalize solute concentrations

Tends to equalize solute concentrations, affecting solution properties


Role in Biological Systems

Plays a role in gas exchange in respiration

Critical for water transport in plants, kidney function, and cell hydration


Molecular Movement

Involves the movement of individual solute molecules

Primarily involves the movement of solvent molecules in clusters


Selectively Permeable Membrane

Not required; can occur in open systems

Requires a selectively permeable membrane



Demonstrated with diffusion in gases or liquids

Demonstrated with osmosis in solutions with semi-permeable membranes


Colligative Properties

Affects colligative properties of solutions

Affects colligative properties of solutions, particularly lowering the vapor pressure


Equilibrium State

Eventually reaches equilibrium

Can reach equilibrium or continue if the solute concentration gradient persists


Affected by Pressure

Affected by pressure differences in gases

Less affected by pressure differences


Application in Dialysis

Used in dialysis to remove waste products from blood

Utilized in dialysis to remove excess solutes from blood


Movement in Cells

Involves solute movement within and between cells

Crucial for water movement into and out of cells


Role in Kidney Function

Important for solute exchange in nephrons

Critical for urine formation and waste removal in the kidneys


Role in Plant Physiology

Less significant for plants in comparison to osmosis

Essential for plant turgor pressure, nutrient uptake, and cell structure


Impact on Cell Shape

May not significantly affect cell shape

Can affect cell shape and volume


Influence on Water Potential

Doesn’t directly influence water potential

Can significantly affect water potential


Role in Food Preservation

Used for processes like drying and salting

Osmotic pressure used in food preservation techniques like pickling

 Also Read: Check out the Principle, Preparation & Uses of Anticoagulants in Hematology Laboratory

Frequently Asked Questions (FAQS) 

Q.1 What is the definition of a selectively permeable membrane?

A selectively permeable membrane is a barrier that permits some chemicals to pass through while blocking others. It allows individual molecules or ions to move according to their size, charge, or other features.

Q.2 How does particle size affect diffusion and osmosis?

Smaller particles diffuse faster than larger particles because they have greater kinetic energy and move faster. The concentration gradient of solute particles, rather than the size of the solute particles themselves, influences the movement of water in osmosis.

Q.3 . What exactly is a concentration gradient?

The difference in concentration of a material between two regions is referred to as a concentration gradient. Diffusion and osmosis take place along concentration gradients, with nanoparticles moving from regions with greater concentrations to lower concentration areas.

Q.4 What factors influence diffusion rate?

The temperature (higher temperatures boost diffusion rates), gradient of concentration (larger gradients lead to more quickly diffusion), area of the surface (larger surface areas enable for more diffusion), and the properties of the material being diffused (size, charge, and solubility) are all factors that influence the rate of diffusion.

Q.5 Is osmosis possible in gases?

Yes, osmosis can take place in gases. It entails the transfer of gas molecules from a higher concentration location to a lower concentration area via a selectively permeable barrier.

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