Question

sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

sodium-potassium atpases

leak channels

ligand-gated channels

voltage-gated channels

Explanation:

• Sodium - potassium ATPases are pumps that use energy (ATP) to move ions against their concentration gradients, not for passive diffusion.
• Ligand - gated channels open in response to a ligand (a chemical signal) binding to them.
• Voltage - gated channels open in response to a change in membrane potential.
• Leak channels are always open (or have a relatively high probability of being open) and allow ions like sodium and potassium to diffuse across the plasma membrane down their concentration gradients.

Answer:

B. Leak channels