Simple diffusion and osmosis
Movement of molecules from a region of high concentration to an area where there is low concentration is called diffusion. On the other hand, osmosis is described as the movement of water from a region where there is a low less concentration of particles that are dissolved to an area of high concentration of suspended particles.
Similarities
The term (simple) in simple diffusion, means the process of diffusion takes place without any external pressure or energy. Thus the similarity between simple diffusion and osmosis is that both happen without the need for energy.
Both osmosis and diffusion lead to equal concentration in two solutions to a membrane. They also work together in making sure that water molecules move from a region of high concentration to low.
Differences
One of the main differences between diffusion and osmosis in relation to the movement of molecules is that diffusion can easily take place in any mixture, either when the two solutions are separated or not, that is diffusion can take place even when solutions are separated by a semipermeable membrane. On the other hand, osmosis occurs only across a semipermeable membrane.
The flow of particles and molecules in osmosis always occurs in one direction, while in diffusion, the movement of molecules and particles moves in all directions. Movement of molecules in osmosis requires water molecules while in diffusion movement of molecules do not necessarily need water. The processes of osmosis can be stopped or reversed by the use of external pressure on the side of the solution, while the whole process of diffusion can never be stopped or reversed.
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