A bilayer of phospholipids.
I think the best answer from the choices would be the first option. Icebergs float in the ocean since i<span>cebergs are composed of freshwater and freshwater is less dense then salt water. The ocean contains salts which contributes to its density which most likely would be higher with that of an iceberg.</span>
Cytoplasm is a jelly like substance that gives the cell its shape. All the organelles of a cell are located inside the cytoplasm
A concentration gradient must exist. hope this helps
