1). Why is the phospholipid molecule so appropriate as the primary structural component of plasma membranes?
a). Phospholipids are completely insoluble in water.
b). Phospholipids form strong chemical bonds between the molecules, forming a stable structure.
c). Phospholipids form a selectively permeable structure.
d). Phospholipids form chemical bonds with membrane proteins that keep the proteins within the membrane.
Answer: c
2). Which increases the fluidity of the plasma membrane?
a). having a large number of membrane proteins
b). the tight alignment of phospholipids
c). cholesterol present in the membrane
d). double bonds between carbon atoms in the fatty acid tails.
Answer: d
3). Which best describes the structure of a plasma membrane?
a). proteins embedded within two layers of phospholipids
b). phospholipids sandwiched between two layers of proteins
c). proteins sandwiched between two layers of phospholipids
d). a layer of proteins on top of a layer of phospholipids
Answer: a
4). What locks all transmembrane proteins in the bilayer?
a). chemical bonds that form between the phospholipids and the proteins
b). hydrophobic interactions between nonpolar amino acids of the proteins and the aqueous environments of the cell
c). attachment to the cytoskeleton
d). the addition of sugar molecules to the protein surface facing the external environment
Answer: b
5). The movement of sodium ions from an area of higher concentration to an area of lower concentration is called _____.
a). active transport
b). osmosis
c). diffusion
d). phagocytosis
Answer: c
6). A cell placed in distilled water will
a). shrivel up.
b). swell.
c). lose water.
d). result in no net diffusion of water molecules.
Answer: b
7). Sucrose cannot pass through the membrane of a red blood cell (RBC) but water and glucose can. Which solution would cause the RBC to shrink the most?
a). a hyperosmotic sucrose solution
b). a hyperosmotic glucose solution
c). a hypoosmotic sucrose solution
d). a hypoosmotic glucose solution
Answer: a
8). Which of the following processes requires membrane proteins?
a). exocytosis
b). phagocytosis
c). receptor-mediated endocytosis
d). pinocytosis
Answer: c
9). Exocytosis involves
a). the ingestion of large organic molecules or organisms.
b). the use of ATP.
c). the uptake of fluids from the environment.
d). the discharge of materials from cellular vesicles.
Answer: d
10). Molecules that are transported into the cell up their concentration gradients do so by
a). facilitated diffusion.
b). osmosis.
c). coupled transport
d). none of the above
Answer: c
