What is an example of a substance that uses these types of transport?Diffusion, Facilitated Diffusion, Osmosis and Active Transport.

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bandmanjoe eNotes educator| Certified Educator

For diffusion and osmosis, water would would be a good example.  Diffusion is where a substance of higher concentration goes to an area of lower concentration in an attempt to equal out the two concentrations.  Osmosis is specifically diffusion by water, where water will diffuse across the cell membrane to an area, inside the cell or outside the cell, to equalize the water concentration in both areas.

For facilitated diffusion, or passive transport, the transfer of the larger glucose molecule (C6H12O6) would be a good example.  This process follows the natural trend of diffusion and osmosis, going from a higher concentration to a lower one, without the expenditure of energy.

For the last one, active transport, energy is required, usually in the form of ATP.  The sodium-potassium pump is a specialized area in the cell membrane that allows the passage of molecules from an area of low concentration to an area of high concentration.  This goes against the natural tendency, so energy is required.