National League for Nursing (NLN PAX) Practice Exam

Facilitated diffusion is indeed the correct answer. This process is a form of passive transport, meaning it does not require any energy from the cell to move substances across the cell membrane. Instead, facilitated diffusion relies on the concentration gradient, allowing molecules to move from an area of higher concentration to an area of lower concentration.

Transport proteins in the membrane assist in this process, allowing certain substances—such as glucose or ions—that cannot pass freely through the lipid bilayer to enter or exit the cell more easily. This mechanism is crucial for maintaining the cell's internal environment and ensuring that it can efficiently take in nutrients and remove waste without expending energy.

In contrast, active transport involves moving substances against their concentration gradient, which does require energy, typically in the form of ATP. Both endocytosis and exocytosis are processes that transport large materials into and out of the cell, respectively, and they also require energy to facilitate the formation of vesicles that engulf or release materials. Thus, facilitated diffusion remains the only option among the choices listed that functions without the need for energy.