The molecules which form the bilayer region of the cell membrane have hydrophilic regions on the outer surface and hydrophobic regions on the inner surface.

The answer is: phospholipid molecules

Explanation:

The plasma membrane of a cell is consists of a lipid bilayer. This lipid bilayer, also known as the phospholipid bilayer, is a polar membrane composed of two layers of lipid molecules, usually amphipathic phospholipid molecules.

The amphipathic phospholipid molecules have a hydrophilic phosphate head on the exterior and a hydrophobic tail consisting of fatty acid chain on the interior of the membrane.

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.