Critical concentration is

A) the concentration of tubulin dimers at which assembly is balanced with disassembly.
B) the concentration of tubulin dimers at which assembly occurs primarily.
C) the concentration of G-actin in most muscle cells.
D) required before nucleation can occur.
E) both choices A and D.

A

Explanation:

Critical concentration is the concentration of tubulin dimers at which assembly is balanced with disassembly, means no net increase or decrease.

The critical concentration is the concentration of either G-actin or the alpha, beta- tubulin complex at which the end will remain in an equilibrium state with no net increase or decrease  It occurs when one end of a filament grows or increase and the other end decrease or shrink.

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.