University of Central Florida (UCF) BSC2010C Biology I Practice Exam 2

During passive transport, the concentration of molecules changes as they move from an area of higher concentration to an area of lower concentration. This process is driven by the concentration gradient, and it continues until the concentrations on both sides of the membrane reach equilibrium. At equilibrium, the molecules are distributed evenly, although they may still move across the membrane due to the inherent movement of particles.

This mechanism is essential for various biological processes, allowing cells to maintain homeostasis by regulating the internal concentration of substances without expending energy. Therefore, the correct choice reflects this dynamic movement towards a state of balance in concentrations, highlighting the fundamental principle of passive transport.