Question

Assertion :Nuclear membrane or karyotheca forms an envelope-like structure called nuclear envelope around the nuclear contents. Reason: Each membrane is not 70-90 $\mathring{A}$ thick and lipoproteinous in nature.

• 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

Answer: (B)

In eukaryotes, nuclear material is surrounded by a double membrane called as nuclear membrane or karyotheca. Each of the two membranes of the nuclear envelope appears to have a trilaminar unit membrane structure made up of lipoproteins similar to that of the endoplasmic reticulum. The membranes are 7 to 8 nanometer in stained thin sections and 10 nanometers in the freeze-etched material. The outer nuclear membrane communicates with the endoplasmic reticulum and has ribosomes on the outer side. Thus, the correct answer is option B