Ions cannot cross through which part of the plasma membrane?
Correct answer: A. Phospholipid bilayer
- A. Phospholipid bilayer
- B. Channel proteins
- C. Both A and B
- D. None of the above
Explanation
The correct answer is the phospholipid bilayer, as this structure acts as a barrier to ions due to its hydrophobic nature. Ions, being charged particles, cannot easily diffuse through the bilayer without the help of membrane proteins. In contrast, channel proteins are specifically designed to facilitate the passage of ions across the plasma membrane, allowing for regulated transport. Therefore, while the phospholipid bilayer restricts the movement of ions, channel proteins enable it. Options C and D are incorrect because they misrepresent the roles of these components in ion transport.
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