Question

Choose the incorrect statement regarding cell membrane.

• A. Generally smaller molecules pass easily and readily than large molecules
• B. Water soluble substance pass through it less readily than lipid soluble substances
• C. Membranes are selectively permeable
• D. None of these

Answer 1

Answer: (D)

None of these

• Phospholipid bilayer is amphiphilic i.e., they have both hydrophilic and hydrophobic end.
• The hydrophilic portion of a phospholipid has a head having a negative charge. It faces outward and contacts with the watery fluid both inside and outside of the cell. It is the polar end.
• The hydrophobic part of a phospholipid layer has a long, nonpolar fatty acid tails. So, it can easily interact with none polar molecules than water. Due to this, it is more favorable for phospholipid to cross the lipid then water because of the interaction of the lipid layer with the interior and exterior of the cell.
• Membrane are selectively permeable because it doesn't allow all the molecules to inside the cell. It selects few molecules which are necessary or can pass through this bilipid layer due to their solubility in this layer.
• So, the correct answer is " none of these" .