Question

multiple choice question
a difference in solute concentration can exist between the cytosol and the interstitial fluid because the ______ prevents their movement.

○ cholesterol

○ aquaporins

○ phospholipid bilayer

○ non - permeable gases

Explanation:

1. Analyze each option:

• Cholesterol: It is a component of the cell membrane that affects fluidity, not primarily a barrier for solute movement between cytosol and interstitial fluid.
• Aquaporins: These are channels for water movement, not for preventing solute movement.
• Phospholipid bilayer: The cell membrane's phospholipid bilayer is selectively permeable, preventing many solutes from freely moving between cytosol and interstitial fluid, allowing concentration differences.
• Non - permeable gases: Gases are generally permeable across cell membranes, and this option is incorrect in context.

Answer:

C. phospholipid bilayer