Final answer:
Carrier proteins require ATP to transport large molecules across the plasma membrane through active transport mechanisms.
Step-by-step explanation:
To transport large molecules across the plasma membrane, carrier proteins require ATP to facilitate movement in active transport. Carrier proteins such as uniporters, symporters, and antiporters move substances against their concentration gradients, which is a process that necessitates an energy input. Although they can also facilitate the movement of glucose and other small, uncharged organic molecules via facilitated diffusion, which does not require energy, active transport mechanisms like the Na+-K+ ATPase or the H+-K+ ATPase specifically use ATP as their energy source.