Question

a sodium-potassium pump within a cell membrane requires energy to move sodium and potassium ions into or out of a cell. the movement of glucose into or out of a cell does not require energy. which statement best describes the movement of these materials across a cell membrane?
a sodium and potassium ions move by active transport, and glucose moves by osmosis.
b sodium and potassium ions move by active transport, and glucose moves by facilitated diffusion.
c sodium and potassium ions move by facilitated diffusion, and glucose moves by osmosis.
d sodium and potassium ions move by facilitated diffusion, and glucose moves by active transport.

Explanation:

1. Recall transport types: Active transport needs energy (ATP), facilitated diffusion is passive (no energy, uses proteins), osmosis is water movement.
2. Analyze sodium - potassium pump: It requires energy, so this is active transport.
3. Analyze glucose movement: It doesn't need energy, so it's not active transport. Osmosis is for water, so glucose can't move by osmosis. Facilitated diffusion is passive (no energy) and uses transport proteins for glucose.
4. Evaluate options:

• Option A: Glucose moving by osmosis is wrong (osmosis is for water). Eliminate A.
• Option B: Sodium - potassium (active transport, needs energy) and glucose (facilitated diffusion, no energy, uses proteins) matches.
• Option C: Sodium - potassium moving by facilitated diffusion is wrong (they need energy, so active transport). Eliminate C.
• Option D: Both sodium - potassium (should be active) and glucose (osmosis wrong) are incorrect. Eliminate D.

Answer:

B. Sodium and potassium ions move by active transport, and glucose moves by facilitated diffusion.