Anatomy and Physiology (ANAPHY) Battery Practice Exam

Facilitated diffusion is indeed an example of passive movement across a cell membrane because it involves the movement of molecules from an area of higher concentration to an area of lower concentration without the use of energy. This process utilizes specific transport proteins embedded in the membrane to assist large or polar molecules, such as glucose or ions, in crossing the lipid bilayer. Since it does not require cellular energy (ATP), it falls under the category of passive transport.

In contrast, active transport involves the movement of substances against their concentration gradient, requiring energy input to transport molecules from areas of lower concentration to areas of higher concentration. Endocytosis and exocytosis are processes that involve the bulk movement of materials into and out of the cell, respectively, and also require energy. Thus, facilitated diffusion stands out as the sole process that exemplifies passive movement across the cell membrane.