Select all of the following that are characteristics of the plasma membrane. a. All living cells have an intact plasma membrane that separates the internal cellular components of the cell from its external environment.
b. The membrane is composed of phospholipids, large organic molecules with hydrophilic, fatty acid tails connected to a hydrophobic, phosphate head that serves a barrier blocking the movement of most molecules.
c. The selective permeability of a phospholipid bilayer membrane is also altered based on the presence of proteins embedded in the membrane.
d. The plasma membrane is able to regulate the movement of materials in and out of the cell because of its composition.