Which of the following is a principle of the fluid mosaic model of cell membrane structure? a. Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains. b. The lipid bilayer is a solid at body temperature, thus protecting the cell. c. All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell. d. Phospholipids form a bilayer that is largely impermeable to water-soluble molecules.

The correct answer is option b. "The lipid bilayer is a solid at body temperature, thus protecting the cell".

Explanation:

The fluid mosaic model describes the fluid character of the cell's membrane structure as a dynamic arrangement of components that include phospholipids, proteins and carbohydrates. One of the principles of the fluid mosaic model is that the lipid bilayer that comprises the cell's membrane is solid at body temperature, thus it functions as a protective mechanism for the cell. The higher the temperature, the more fluid the cell membrane is.