B is not one of the three domains of life
Microtubules are composed of two different types of tubulin. Namely, these simpler units are called alpha-tubulin and beta-tubulin. These subunits are essentially tightly bound together to form heterodimers. In the microtubule structure, they are arranged in an organized manner in such a way that they in parallel direction with protofilaments.
Earths elliptical orbit around the sun with winter occurring when the earth is far away from the sun and summer is closest to it how ever our planets distance from the sun has a little effect on the onset of seasons
hope this makes sense if not just message me and ill try to put it in a more understanding way :)
These are the ones i was taught
1. molecule transport
2. signal receptors
3. intercellular junctions
4. cell to cell communication and recognition
5. gives the cell structure
6. protects the cell
7. acts as enzymes
