Question

Plasma membrane does not have carrier molecules for

• A. Active transport
• B. Simple diffusion
• C. Faciliated diffusion
• D. $N{a}^{+}-K^{+}$ pump

Answer 1

The correct option is B Simple diffusion

In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.
For active transport, as the movement is against the concentration gradient, carriers or pumps are required. Similarly with Na-K pump.
Simple diffusion is just the movement of molecules from a place of higher concentration to lower concentration without any carrier molecules.
Thus, the correct answer is option (B).