Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which type of transport requires energy to move substances across the plasma membrane?

1. Facilitated diffusion

2. Diffusion

3. Active transport

4. Osmosis

The correct answer is: Active transport

Active transport is the process that requires energy to move substances across the plasma membrane against their concentration gradient. This means that molecules are moved from an area of lower concentration to an area of higher concentration, which is not a spontaneous process and therefore requires energy typically in the form of ATP. In contrast, facilitated diffusion, diffusion, and osmosis are passive processes that do not require energy. Facilitated diffusion uses transport proteins to help move substances across the membrane without the input of energy, while diffusion refers to the movement of particles from a region of higher concentration to one of lower concentration until equilibrium is reached. Osmosis is a specific type of diffusion that involves the movement of water across a selectively permeable membrane. Since all these processes rely on existing concentration gradients, they do not require additional energy input. Thus, the requirement for energy in active transport distinguishes it from these other transport mechanisms.