Osmosis
plasma membrane in cells
The plasma membrane is the boundary between the cell and its environment. It regulates what enters and exits the cell. Cells must maintain an appropriate amount of molecules to function inside them. They must also have a way to keep things out or to allow things to enter. It can be described as the guard of the city.
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diffusion
It is the random movement of molecules of a substance from an area of high concentration of that substance to an area of low concentration of that substance. This kind of activity does not require any energy.
osmosis
It is the movement of a solvent (usually water) through a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration. It is a kind of diffusion.
osmosis and the survival of cells
It is important for a cell’s survival to regulate osmosis in order to maintain an optimal internal environment. Therefore, osmosis can keep the concentration of substances within the cell at a safe range for the cell itself to survive. In order to regulate osmosis, a cell uses a fluid mosaic of lipids, proteins, and carbohydrates. This fluid structure is known as the cell membrane.