Regarding plasma membranes, which of the following statements is false?
(a) cholesterol can increase the fluidity of plasma membranes that are rich in saturated fatty acids.
(b) the thickness of the plasma membrane is only about 1 nm
(c) the er, golgi, and secretory vesicles of the endomembrane system are all involved in plasma membrane biosynthesis
(d) plasma membrane channel and carrier proteins are amphipathic

The correct answer to the question: Regarding plasma membranes, which of the following statements is false, would be, B: The thickness of the plasma membrane is only about 1 nm.

Explanation:

The plasma membrane is the structure of the cell that provides a protective barrier, between a cell´s intracellular environment and the extracellular matrix. Furthermore, aside from providing structural support, and protection, a cell´s membrane also serves as a communication media between the cells, and between a cell and all other elements outside of it. This membrance is formed by a phospholipid bilayer, with a space in between the two layers where the tail ends meet and it also has in its structure cholesterol and other lipids that allow the membrane to be fluid, but also structurally strong. However, what is not true is the thickness, as it is known that plasma membranes´ thickness actually lies between 7.5 to 10 nm, and not merely 1 nm. This is why the answer is B.