The preferential use of phosphatidylinositol and phosphatidylethanolamine in the cytoplasmic leaflet of membranes leads to increased:
a. fluidity in the cytoplasmic leaflet.
b. negative charge on the cytoplasmic leaflet.
c. association with positively charged amino acids by the cytoplasmic leaflet. curvature toward the cytoplasmic face.
d. all of the answers are correct.

The best answer to the question: The preferential use of phosphatidylinositol and phosphatidylethanolamine in the cytoplasmic leaflet of membranes leads to increased:___ would be, D: All of the answers are correct.

Explanation:

There is still a lot of debate among scientists as to the exact way in which phospholipids are distributed between the two leaflets of a cell´s plasma membrane, but what they do know is that there are four kinds, and that phosphatidylinositol (a sterol) and phosphatidylethanolamine appear most commonly on the cytosolic, or cytoplasmic side of the membrane. They also believe that it is this particular arrangement which allows the cytoplasmic side of the membrane to be slightly negatively charged and this role will play a major part in a membrane´s ability to generate an action potential. Also, it is known that these negatively charged ends of the bilayer will allow certain proteins, positively charged ones, to be inserted, and connected to it, to become transporters, or mediators in action potentials and normal activities of cells. Finally, since fatty acids and cholesterol are associated with phospholipids, but have a tendency to be attracted to these particular two types, they tend to give the overall structure fluidity, but also permit  the inner leaflet to assume its particular circular shape around the cytoplasm. This is why the answer is D.