Question

Which of the following is a function of the steep Na+/K+ gradient across the cell membrane?

A. provides energy for coupled transport
B. creates electrochemical impulses
C. maintains osmotic pressure
D. All apply.

Answer 1

The Na+/K+ gradient across the cell membrane has several functions: it provides energy for coupled transport of substances, creates electrochemical impulses for nerve transmission, and maintains osmotic pressure within the cell. The correct answer is that all listed functions apply to the role of the Na+/K+ gradient.

Step-by-step explanation:

The steep Na+/K+ gradient across the cell membrane serves several critical functions:

• A. Provides energy for coupled transport: The energy of the electrochemical gradient established by the primary active transport (like the sodium-potassium pump) is used to transport substances like amino acids and glucose into the cell.
• B. Creates electrochemical impulses: The movement of Na+ into the cell during an action potential, which is facilitated by the electrochemical gradient, is essential for the transmission of nerve impulses.
• C. Maintains osmotic pressure: Proper ion balance is necessary to regulate osmotic pressure within the cell, preventing excessive swelling or shrinking due to water movement.

Therefore, the correct answer to the student's question is D. All apply. Each of the functions listed is a critical role played by the Na+/K+ gradient across the cell membrane.