Question

Which of the following processes cause substances to move across membranes without the expenditure of cellular energy?

• A. Endocytosis
• B. Exocytosis
• C. Active transport
• D. Diffusion

Answer 1

Answer: (D)

Diffusion

Endocytosis is an energy-using process by which cells absorb molecules by engulfing them.
Exocytosis is also an energy consuming process by which a cell directs the contents of secretory vesicles out of the cell membrane and into the extracellular space.
Active transport is the movement of molecules across a cell membrane in the direction against their concentration gradient, i.e., moving from a low concentration to a high concentration and this uses cellular energy.
Passive transports like diffusion do not require additional expenditure of cellular energy during the movement of a substance from a region of high concentration to a region of low concentration, i.e., along with the concentration gradient.