Changes in membrane potential graphed an action potential

Question

Assignment:

(1) Solution A and B are separated by a membrane that is permeable to Mg²⁺ and impermeable to C1-. Solution A contains 0.1 mM MgC1₂. solution B contains 100 mM MgC1₂.

Mgt⁺ will be at electrochemical equilibrium when solution A is around_____ mV.

A. + 180 mV

B. - 180 mV

C. + 90 mV

D. - 90 mV

E. + 60 mV

F. - 60 mV

(2) Refer to the figure showing changes in membrane potential graphed during an action potential production. For step 3 in the figure,

A. Voltage-gated K⁺ channels are open.

B. Voltage-gated Na⁺ channels are open.

C. Voltage-gated Ca²⁺ channels are open.

D. Voltage-gated Mg²⁺ channels are open.

E. Voltage-gated C1-hannels are open.