Question

sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? voltage - gated channels ligand - gated channels leak channels sodium - potassium atpases

Explanation:

To determine the correct channel for sodium and potassium ion diffusion across cell plasma membranes:

• Voltage - gated channels open/close based on membrane potential changes, not for constant ion diffusion.
• Ligand - gated channels open/close when a ligand (molecule) binds, not for passive, constant ion movement.
• Leak channels (or “leakage channels”) are always open, allowing continuous, passive diffusion of ions like Na⁺ and K⁺ across the membrane, which matches the description of “diffuse across... of all cells” (constant, passive movement).
• Sodium - potassium ATPases are active transporters (use ATP) to pump ions against gradients, not for diffusion.

Answer:

C. Leak channels