Apr 10, 2019 · Diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration. Passive diffusion is the movement of molecules across a membrane, such as a cell membrane. The movement does not require energy. In facilitated diffusion, a molecule is transported across a membrane with the help of a carrier protein. Passive transport is of four main types, which are, facilitated transport, diffusion, filtration and osmosis. In filtration, solids are restrained while liquids are allowed to freely pass. In diffusion, there is spread of molecules in a random manner from their higher concentration gradient to their lower concentration gradient.
Jan 01, 2001 · Facilitated diffusion or uniport is the simplest form of passive carrier-mediated transport and results in the transfer of large hydrophilic molecules across the cell membrane. Cotransport or symport is a form of secondary active transport.