11-1 Which of the following phenomena will be observed if a cell's membrane is pierced?
(a) the membrane reseals
(b) the membrane collapses
(c) a tear is formed
(d) the membrane expands - A
11-2 The plasma membrane serves many func ons, many of which depend on the presence of
specialized membrane proteins. Which of the following roles of the plasma membrane could s ll occur if
the bilayer were lacking these proteins?
(a) intercellular communica on
(b) selec ve permeability
(c) cellular movement
(d) import/export of molecules - B
11-4 Which type of lipids are the most abundant in the plasma membrane?
(a) phospholipids
(b) glycolipids
(c) sterols
(d) triacylglycerides - A
11-6 Which of the following membrane lipids does not contain a fa y acid tail?
(a) phospha dylcholine
(b) a glycolipid
(c) phospha dylserine
(d) cholesterol - D
, 11-7 Forma on of a lipid bilayer is energe cally favorable. How does this arrangement result in higher
entropy for the system, and thus make bilayer forma on energe cally favorable?
(a) Polar head groups form a hydrogen-bonding network at the interface with water.
(b) Water molecules form cagelike structures around hydrophobic molecules.
(c) Hydrogen bonds form between neighboring polar head groups in the bilayer.
(d) Fa y acid tails are highly saturated and flexible. - B
11-8 Which of the following statements is true?
(a) Phospholipids will spontaneously form liposomes in nonpolar solvents.
(b) In eukaryotes, all membrane-enclosed organelles are surrounded by one lipid bilayer.
(c) Membrane lipids diffuse within the plane of the membrane.
(d) Membrane lipids frequently flip-flop between one monolayer and the other. - C
11-9 A bacterium is suddenly expelled from a warm human intes ne into the cold world outside. Which
of the following adjustments might the bacterium make to maintain the same level of membrane
fluidity?
(a) Produce lipids with hydrocarbon tails that are longer and have fewer double bonds.
(b) Produce lipids with hydrocarbon tails that are shorter and have more double bonds.
(c) Decrease the amount of cholesterol in the membrane.
(d) Decrease the amount of glycolipids in the membrane. - B
11-12 Some lipases are able to cleave the covalent bonds between the glycerol backbone and the
a ached fa y acid. What final products do you expect to accumulate through the ac on of the enzyme
monoacylglycerol lipase?
(a) phosphoglycerol and free fa y acid
(b) sterol and glycerol
(c) free phosphate and glycerol
(d) glycerol and free fa y acid - D
11-13 Which of the following phospholipid precursors is the most hydrophobic?