That should be the cell membrane. The cell membrane acts as a filter in and out.
<span>tubulin, the microtubule protein</span>
Answer is the first option Place a metal paper clip on a table and slowly bring each electromagnet closer to the paper clip to see which can attract the paper clip from a greater distance.
I don't know why but I find your questions a bit too easy..
D! Commensalism is one organism benefits and the other is unaffected !