Answer:
Microtubules, like actin filaments, are dynamic structures: they can grow and shrink quickly by the addition or removal of tubulin proteins. Also similar to actin filaments, microtubules have directionality, meaning that they have two ends that are structurally different from one another. I hope this helps :)
Answer:
c. Hydrogen
Explanation:
Do I really need to explain...
They give us the energy we need to move and to speak and to live they do that for all the organisms on earth