1. Cholesterol maintains the fluidity of the phospholipid bilayer: if temperature is too cold it prevents them from crystallising and if it is too warm it prevents them from moving away from each other.
2. The plasma membrane regulates which molecules can pass in and out this is important because a cell must maintain a certain composition in order to continue functioning. The plasma membrane also seperates intracellular and extracellular fluid. This is important because intracellular fluid suits the internal environment of the cell and enables it to thrive. Extracellular fluid contains other things which may harm organelles.
3. They would diffuse directly through the phospholipids into the intracellular environment down their concentration gradient via simple diffusion.
4. B oxygen molecules
5. A
6. A- exocytosis
B- endocytosis (is that pinocytosis?
I cannot tell whether it is a liquid)
C - endocytosis (phagocytosis)