Difference Between Osmosis and Diffusion

The question often arises as to what is the difference between osmosis and diffusion, which are two forms of biological transport. Osmosis is the movement of solvent particles from a solution that is diluted to a more concentrated one. In contrast, diffusion is the movement of particles from a higher concentration region to a region of lower concentration.

Definition of Osmosis

Osmosis refers to a type of diffusion in which a substance crosses a semipermeable membrane so as to balance the concentrations of another substance. Furthermore, in the field of biology, it happens when a solvent such as water flows into a cell or out of it on the basis of a solute’s concentration like salt. Also, the occurrence of osmosis takes place spontaneously without any use of cell energy.

Definition of Diffusion

Diffusion can be defined as a physical process that refers to the net movement of molecules from a region of high concentration to a lower concentration region. This definition certainly makes the difference between osmosis and diffusion more clear. Furthermore, the material that diffuses could be of any state of matter-solid, liquid, or gas.

Difference Between Osmosis and Diffusion

Important difference between osmosis and diffusion

Parameter	Osmosis	Diffusion
Type of substance	Only water or another solvent can move from a region of higher concentration to lower concentration.	Any type of substance can move from an area of higher concentration to lower concentration.
Semi-permeable membrane	It requires a semi-permeable membrane.	It has no need of a semi-permeable membrane.
Medium	It takes place only in a liquid medium.	It takes place in any medium- solid, liquid, or gas.
Concentration	The solvent’s concentration does not become equal on both of the membrane sides.	The diffusion substance’s concentration equalizes to fill the space available.
Dependence	It depends on solute potential. Furthermore, it mainly depends on the number of solute particles in the solvent.	It does not depend on solute potential, water potential, or pressure potential. Furthermore, it depends mainly on the presence of other particles.
Hydrostatic pressure and turgor pressure	These two pressures oppose osmosis.	These two pressures do not normally apply to diffusion.
Movement	The movement in osmosis is such that it seeks to equalize solvent concentration, though it does not happen.	The movement in diffusion equalizes concentration throughout the entire system.

More Details About Osmosis

In order to better understand the difference between osmosis and diffusion, let us delve into more details of these concepts. Osmosis is a process that deals with chemical solutions containing two parts- a solvent and a solute. Furthermore, when a solute dissolves in a solvent, a solution results as an end product.

There are three different types of solutions that influence cells due to osmosis. Moreover, the first type of solution is the isotonic solution that has the same concentration of solutes inside as well as outside the cell. Furthermore, in a hypotonic solution, there is a higher concentration of solutes inside the cell rather than outside. Finally, in a hypertonic solution, there is more solute outside the cell in comparison to inside.

Osmosis affects plant and animal cells in different manners because their cells can tolerate different concentrations of water. For example, in a hypotonic solution, an animal cell will fill an excessive amount of water and lyse, or burst open. However, plant cells have a higher requirement of water than animal cells, and their bursting does not occur due to their thick cell walls.

More Details About Diffusion

A major characteristic of diffusion is the movement of molecules along the concentration gradient. Furthermore, this movement does not has direct involvement of high-energy molecules such as adenosine triphosphate (ATP).

There is certainly a difference between diffusion and reverse osmosis. Furthermore, diffusion refers to a movement of molecules from higher to lower concentration region. In contrast, reverse osmosis happens when the movement of water is across the membrane against the concentration gradient, from lower to a higher concentration.

There is also a difference between diffusion and active transport. This is because active transport refers to a process of movement of molecules and ions against their concentration gradient with the expenditure of energy. In contrast, in diffusion, there is no expenditure of energy.

FAQs About Osmosis and Diffusion

Question 1: Give any one difference between osmosis and diffusion in a brief manner?

Answer 1: One difference between osmosis and diffusion can certainly be with regards to the type of medium. Furthermore, diffusion can happen in any medium-solid, liquid, or gas. In contrast, osmosis happens only in a liquid medium.

Question 2:  What is active transport?

Answer 2: Active transport refers to a process of movement of molecules and ions against their concentration gradient due to the expenditure of energy.