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Unformatted text preview: Concept 8.3 Passive transport is diffusion of a substance across a membrane with no energy investment Diffusion is the tendency of molecules of any substance to spread out in the available space. Diffusion is driven by the intrinsic kinetic energy (thermal motion or heat) of molecules. Movements of individual molecules are random. However, movement of a population of molecules may be directional. Imagine a permeable membrane separating a solution with dye molecules from pure water. If the membrane has microscopic pores that are large enough, dye molecules will cross the barrier randomly. The net movement of dye molecules across the membrane will continue until both sides have equal concentrations of the dye. At this dynamic equilibrium, as many molecules cross one way as cross in the other direction....
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.
- Fall '10