Question

How many longitudinal filaments are found in the wall of a microtubule?

• A. 9
• B. 11
• C. 13
• D. 15

Answer 1

The correct option is C 13

Microtubules are unbranched hollow tubules of indefinite length about 25nm of thickness with 15nm core and boundary formed of 13 helically arranged protofilaments of globular molecules of $\alpha$ and $\beta$- tubulins.

So, the correct answer is option C.