Which of the following is true about the movement of ions across excitable living membranes?
A) Ions always move actively across membranes through leakage channels.
B) Sodium gates in the membrane can open in response to electrical potential changes.
C) Ions always move passively across membranes.
D) Ions always move from an area of higher concentration to an area of lower concentration.

Question

Quizplus · Accepted Answer

Sodium channels in excitable living membranes can open in response to changes in electrical potential, allowing sodium ions to move across the membrane. This is an example of active transport, as it requires the use of energy to move ions against their concentration gradient. Passively, ions can move across membranes through leakage channels, but this does not always occur. Ions may also move from an area of higher concentration to an area of lower concentration, but this is only true for passive transport, not active transport.

Which of the Following Is True About the Movement of Ions