Question

question 1 if diffusion of na+ takes place using facilitated diffusion, which of the following must be true? a the cell membrane must have na+ channels. b the cell membrane must have na+/k+ pumps. c na+ diffuses directly across the cell membrane. d na+ must be at higher concentrations outside the cell. e na+ must be at higher concentrations inside the cell.

Explanation:

Facilitated diffusion of Na+ requires transport proteins like channels or carriers. Na+/K+ pumps are for active - transport, not for simple facilitated diffusion. Na+ does not diffuse directly across the cell membrane due to its charge. For facilitated diffusion of Na+, there must be a concentration gradient with higher Na+ outside the cell to drive the movement.

Answer:

D. Na+ must be at higher concentrations outside the cell.