49) In the fluid-mosaic model that describes plasma membranes,
A) there are three layers of glycerophospholipid molecules.
B) two layers of glycerophospholipid molecules have their nonpolar sections oriented to the inside of the
membrane.
C) two layers of glycerophospholipid molecules have their nonpolar sections along the outer surface of
the membrane.
D) A single row of glycerophospholipid molecules forms a barrier between the inside and outside of the
cell.
E) two layers of proteins separate the contents inside a cell from the surrounding fluids.
50) Channel proteins in cell membranes serve what function?
A) They add strength and rigidity to the membrane.
B) They provide pathways for water and electrolytes to move through cell membranes.
C) They form the bilayer portion of the membrane.
D) They allow nonpolar substances to move through the membrane.
E) They prevent interactions between the nonpolar tails of the phospholipids which gives the membrane
its fluidity.
51) According to the fluid-mosaic model of a cell membrane, the main component of a membrane is
A) a lipid bilayer.
B) a membrane protein.
C) a glycoprotein.
D) a steroid.
E) a prostaglandin.
52) The type of lipid that gives a cell membrane its shape is a
A) triacylglycerol.
B) glycerophospholipid.
C) prostaglandin.
D) bile salt.
E) wax.