Diffusion

Diffusion is the net movement of molecules of a substance from a region of their higher concentration to a region of their lower concentration. Net movement means there are more molecules moving in one direction than in the opposite direction.

Example: Opening a bottle of perfume in a room will result in the gradual diffusion of the perfume from the region of higher concentration (the bottle) out into the room. Diffusion will continue until the perfume has a more or less uniform concentration throughout the bottle and room.

Osmosis

It can be defined as the movement of water molecules from a higher water concentration area to the area of less water concentration through a semipermeable membrane. For example, water in the roots of plants is transported through osmosis.

Difference between diffusion and osmosis:

Osmosis

Diffusion

It happens only in the liquid state.

It occurs in all states of matter i.e., solids, liquids or gases.

It should be movement of only water or solvent through semipermeable membrane from lower concentration to higher concentration.

Any type of substance that moves from higher concentration area to lower concentration area.

It is applied only for the solvent part of the solution.

Diffusion is applied to all states of matter.

 

It requires semipermeable membrane.

This phenomenon does not require semipermeable membrane.

Osmotic Solutions

There are three different types of solutions:

Isotonic Solution
Hypertonic Solution
Hypotonic Solution

An isotonic solution is one that has the same concentration of solutes both inside and outside the cell.

A hypertonic solution is one that has a higher solute concentration outside the cell than inside.

A hypotonic solution is one that has a higher solute concentration inside the cell than outside.

 

Types of Osmosis

Osmosis is of two types:

Endosmosis– When a substance is placed in a hypotonic solution, the solvent molecules move inside the cell and the cell becomes turgid or undergoes de plasmolysis. This is known as endosmosis.
Exosmosis– When a substance is placed in a hypertonic solution, the solvent molecules move outside the cell and the cell becomes flaccid or undergoes plasmolysis. This is known as exosmosis.


 

 

 

 

 

Diffusion and Osmosis

Diffusion and Osmosis

Diffusion: It is the movement of any substance from higher concentration to lower concentration. Have you noticed the fragrance of your favorite food at your home when it surprisingly cooked for you by your mom. This is due to the process diffusion. When it is being cooked in kitchen its fragrant  molecules from kitchen start moving out into the kitchen’s surroundings and with time get dispersed in the air. The diffusion is seen in solids, liquids and gases but the rate of diffusion is faster in gases. This is because gas particles are energetic as they possess high kinetic energy. The movement of gases in and out from the cell occurs by diffusion

Osmosis: It is the movement of pure liquid from  higher concentration to lower concentration across the semipermeable membrane . For example: if you take two flasks and fill one with low sugar so lution and other flask with highly concentrated sugar solution. Both the beakers are separated by a semipermeable membrane. Then we will notice that the water will move from the beaker where it is more to the side where it is less. The membrane allows only water to pass through it not sugar as it is semi-permeable that is selectively permeable.

Types of solutions

We can make three different types of solutions that is :

1. Hypotonic solution – The solution that has higher water concentration.

2. Hypertonic solution- The solution that has less water concentration.

3. Isotonic solution-The solution that has the same concentration of water as in cell.

Now let’s do an activity in which we will be placing a cell say red blood cell in three different solutions. Let’s see what happens:

Cells placed in different types of solutions

This is because when it is placed in a hypotonic solution, the water from solution moves into cell (endo-osmosis) due to  which cell starts swelling up .The fully swollen cell in which the protoplasm almost touches the cell membrane is called Turgid cell.

Have you seen the red blood cell kept in hypertonic solution looks flaccid This is because when it is placed in a hypertonic solution, the water from cell moves into solution (exo-osmosis) occurs due to which cell starts shrinking up .The cell whose protoplasm almost gets shrunk is called flaccid cell.

Have you seen the cell in isotonic solution It remains as such. Nothing happens. The reason being the concentration of cell and a solution is the same.

Q. Have you noticed that sometimes when you forget to water plants especially in summers they droop, dry and ultimately they are about to die .

A. This is because the water from the plant is moving out due to transpiration. So, when there is no water left in them they start to droop. This basically occurs due to exo-osmosis. But when it is watered again, the endo osmosis occurs and it again become turgid .this is called plasmolysis (shrinkage) and deplasmolysis (again becoming healthier).