What is Diffusion?

Diffusion is defined as the process wherein the molecules merge as a result of their kinetic energy of random motion.


For instance:

Take a beaker filled with water. Add a few crystals of copper sulfate carefully and leave the unit undisturbed for some time. We can observe that the water in the beaker is uniformly colored. In this experiment, both copper sulfate and water diffuse independently.

Hence concentration gradient would be nothing other than the process by which particles known by the name of solutes travel through a solution from a higher particle numbered area to a lower numbered area.

 Examples of Diffusion

  • A teabag immersed in a cup of hot water will diffuse into the water and change its color.
  • A spray of perfume or room freshener will get diffused into the air by which we can sense the odor.
  • Sugar gets dissolved evenly and sweetens the water without having to stir it.
  • As we lit the incense stick, its smoke gets diffused into the air and spreads throughout the room.
  • By adding boiling water into the dried noodles, the water diffuses causing rehydration and making dried noodles plumper and saturated.

 Types of Diffusion

Since distribution occurs in a variety of conditions, the following are the terms that specify different types of diffusion. Simple diffusion and Facilitated diffusion are two different types of Diffusion

Simple diffusion

A process in which the substance moves through a semipermeable membrane without any help from transport proteins.  For example, Bacteria delivers small nutrients, water, and oxygen into the cytoplasm through simple diffusion

Facilitated diffusion

Facilitated diffusion

The diffusion of the content over a cell membrane by means of transport proteins. Facilitated diffusion is a passive movement of molecules across the cell membrane from the region of higher concentration to the region of lower concentration by means of a carrier molecule.

Dialysis: It is the diffusion of solutes across a selected permeable membrane. A selected permeable membrane is the one that allows specific content to pass through and other substances to pass slowly.

Osmosis: It is the movement of water molecules from the region of higher water concentration to the region of lower water concentration through a semipermeable membrane. It is the diffusion of the solvent across a selected permeable membrane. Since water is solvent in every living being, biologists define osmosis as the diffusion of water across a selected permeable membrane.

For example, Plants take water and mineral from roots with the help of osmosis.


Causes of Diffusion

Diffusion is a natural and physical process, which happens on its own, without stirring, shaking or wafting the solutions. In gases and liquids state of matter, particles move randomly from one place to another, during which the particles collide with each other or with the container. This brings the change in their direction.

Significance of Diffusion

Diffusion is an important process, which is involved in the different life processes. As mentioned above, it is the net movement of particles, ions, molecules, solution, etc. In all living species, diffusion plays an important role in the movement of the molecules during the metabolic process in the cells. There are various naturally occurring processes that depend on the diffusion of molecules, such as:

During the process of respiration, this process helps in diffusing the carbon dioxide gas out through the cell membrane into the blood.

Diffusion also occurs in plant cells. In all green plants, water present in the soil diffuses into plants through their root hair cells.

Factors Affecting Diffusion

There are a few factors that affect the process of diffusion, which individually and collectively alter the rate and extent of diffusion. These factors include:

  • Temperature.
  • Area of Interaction.
  • Size of the Particle.
  • The steepness of the concentration gradient.

Learn more about Diffusion, its types, importance and other related topics @ BYJU’S Biology

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