Question

Assertion :A Cell membrane shows fluid behaviour. Reason: A membrane is a mosaic of lipids and proteins.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

A Cell membrane shows fluid behaviour. It was explained by Fluid-Mosaic model. According to this model, the membrane does not have a uniform disposition of lipids and proteins but is instead a mosaic of the two. Further, the membrane is not solid but is quasifluid. The quasifluid nature of the membrane is shown by their properties of quick repair, dynamic nature, ability to fuse,expand and contract, grow during cell growth and cell division, secretion, endocytosis and formulation of intercellular junctions. Fluid-Mosaic model postulates that the lipid molecules are present in a viscous bilayer as in lamellar model. Protein molecules occur at places both inside and on the outer side of lipid bilayer- protein icebergs in a sea of lipids. The internal proteins are called intrinsic or integral proteins while the external ones are known as extrinsic or peripheral proteins.