Q: Which of the following equations best represents the stoichiometry of the sodium-potassium pump?

$$3 \mathrm{Na}^+_{\text{in}} + 2 \mathrm{K}^+_{\text{out}} + \mathrm{ATP} \rightarrow 3 \mathrm{Na}^+_{\text{out}} + 2 \mathrm{K}^+_{\text{in}} + \mathrm{ADP} + \mathrm{P}_i$$

Question 1

Which of the following best describes the main function of the sodium-potassium pump as illustrated in the first image?

Accepted Answer

It uses ATP to move sodium ions out of the cell and potassium ions into the cell against their concentration gradients.

Question 2

In the sodium-potassium pump cycle, which step directly involves the hydrolysis of ATP?

Accepted Answer

When sodium ions bind to the pump and ATP is hydrolyzed, phosphorylating the pump.

Question 3

Refer to the first image. What is the correct order of events for the sodium-potassium pump cycle?

Accepted Answer

A, D, E, F, C, B

Question 4

How many sodium ions are transported out of the cell for each ATP molecule hydrolyzed by the sodium-potassium pump?

Accepted Answer

$$3$$

Question 5

How many potassium ions are transported into the cell for each ATP molecule hydrolyzed by the sodium-potassium pump?

Accepted Answer

$$2$$

Question 6

What is the primary energy source for the sodium-potassium pump?

Accepted Answer

ATP hydrolysis

Question 7

Which of the following best describes the function of the membrane protein on the left in the second image?

Accepted Answer

It is a channel protein allowing passive diffusion of molecules.

Question 8

Which process is illustrated by the membrane protein on the right in the second image?

Accepted Answer

Primary active transport

Question 9

What is the main difference between the two membrane proteins shown in the second image?

Accepted Answer

One is a channel protein for passive transport, the other is a pump protein for active transport.

Question 10

Which of the following equations best represents the stoichiometry of the sodium-potassium pump?

Accepted Answer

$$3 \mathrm{Na}^+_{	ext{in}} + 2 \mathrm{K}^+_{	ext{out}} + \mathrm{ATP} ightarrow 3 \mathrm{Na}^+_{	ext{out}} + 2 \mathrm{K}^+_{	ext{in}} + \mathrm{ADP} + \mathrm{P}_i$$

Question 11

Which of the following best explains why the sodium-potassium pump is essential for maintaining the resting membrane potential?

Accepted Answer

It creates a net negative charge inside the cell by exporting more sodium ions than it imports potassium ions.

Study Guide: Cell Structure and Membrane Transport (ANP College Level)

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