Question

Read the assertion and reason carefully to mark the correct option in question


Assertion: Lipids present in the outer and inner side of the bilayer membrane are commonly different.

Reason: Oligosaccharides are attached to external surface as well as inner surface of a biomembrane.

• A. If both assertion and reason are false.
• B. If both assertion and reason are true but the reason is not the correct explanation of the assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are true and the reason is the correct explanation of the assertion.

Answer 1

The correct option is C If assertion is true but reason is false.

Elaboration:

The plasma membrane is primarily composed of phospholipid bilayer, membrane proteins and carbohydrates. The phospholipid bilayer on the outer side comprises of lipids like phosphatidylcholine and sphingomyelin, whereas on the inner side are present lipids like phosphatidylethanolamine and phosphatidylserine. Thus the lipids present in the outer surface and inner side of the bilayer membrane are commonly different.

The oligosaccharides like glycolipids and glycoproteins are attached on the external surface and not to the inner surface of a biomembrane.
Hence, assertion is true but the reason is false.

Final answer: (C) If assertion is true but reason is false