Question

Which of the following is/are true regarding leak channels in a typical mammalian neuron?

1) the Na/K pump pumps Na and K in the same direction in which they flow through leak channels
2) leak channels are always open
3) there is an equal number of Na and K leak channels
4) two choices are true
5) three choices are true

Answer 1

In terms of leak channels in a typical mammalian neuron, only the statement that leak channels are always open is true. The sodium-potassium pump moves ions in opposite directions to leak channels at a specific ratio, and there's no requirement for an equal number of Na+ and K+ leak channels.

Step-by-step explanation:

The question relates to the leak channels in animal cell membranes and the sodium-potassium pump (Na+/K+ ATPase), which helps maintain the electrochemical gradient.

• 2) Leak channels are always open, which allows the ions to diffuse through the membrane according to the concentration gradient.
• The sodium-potassium pump does not pump Na+ and K+ ions in the same direction as they flow through leak channels; instead, it pumps three Na+ out for every two K+ ions moved into the cell, hence statement 1) is false.
• Regarding the number of Na+ and K+ leak channels, there is not necessarily an equal number (statement 3) is false).

Thus, only one choice is true, which is statement 2).