GENERAL HISTOLOGY

Detailed explanation-1: -Passive transport does not require the cell to expend any energy and involves a substance diffusing down its concentration gradient across a membrane.

Detailed explanation-2: -Facilitated diffusion is a passive process: the solutes move down their concentration gradient and do not require the expenditure of cellular energy for this process. Carrier proteins and channel proteins allow for the diffusion of molecules across the cell membrane.

Detailed explanation-3: -Like simple diffusion, facilitated diffusion occurs down an electrochemical potential gradient; thus it requires no input of metabolic energy.

Detailed explanation-4: -Three transport processes that do not require energy are; diffusion, osmosis and facilitated diffusion.

Detailed explanation-5: -Simple diffusion does not require energy: facilitated diffusion requires a source of ATP. B. Simple diffusion can only move material in the direction of a concentration gradient; facilitated diffusion moves materials with and against a concentration gradient.