5 Written questions
2 Matching questions
- 22) Which of the following is true of the evolution of cell membranes?
A) Cell membranes have stopped evolving now that they are fluid mosaics.
B) Cell membranes cannot evolve if the membrane proteins do not.
C) The evolution of cell membranes is driven by the evolution of glycoproteins and glycolipids.
D) All components of membranes evolve in response to natural selection.
E) An individual organism selects its preferred type of cell membrane for particular functions.
- 45) The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on?
A) It will be on the cytoplasmic side of the ER.
B) It will be on the side facing the interior of the ER.
C) It could be facing in either direction because proteins are properly reoriented in the Golgi apparatus.
D) It doesn't matter, because the pump is not active in the ER.
- a a
- b d
5 Multiple choice questions
5 True/False questions
23) Why are lipids and proteins free to move laterally in membranes?
A) The interior of the membrane is filled with liquid water.
B) Lipids and proteins repulse each other in the membrane.
C) Hydrophilic portions of the lipids are in the interior of the membrane.
D) There are only weak hydrophobic interactions in the interior of the membrane.
E) Molecules such as cellulose can pull them in various directions. → c
37) Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
A) simple diffusion
C) active transport pumps
E) facilitated diffusion → e
33) In which of the following would there be the greatest need for osmoregulation?
A) an animal connective tissue cell bathed in isotonic body fluid
B) cells of a tidepool animal such as an anemone
C) a red blood cell surrounded by plasma
D) a lymphocyte before it has been taken back into lymph fluid
E) a plant being grown hydroponically (in a watery mixture of designated nutrients) → b
Cystic fibrosis is a genetic disease in humans in which the CFTR protein, which functions as a chloride ion channel, is missing or nonfunctional in cell membranes.
73) In the small airways of the lung, a thin layer of liquid is needed between the epithelial cells and the mucus layer in order for cilia to beat and move the mucus and trapped particles out of the lung. One hypothesis is that the volume of this airway surface liquid is regulated osmotically by transport of sodium and chloride ions across the epithelial cell membrane. How would the lack of a functional chloride channel in cystic fibrosis patients affect sodium ion transport and the volume of the airway surface liquid?
A) Sodium ion transport will increase; higher osmotic potential will increase airway surface liquid volume.
B) Sodium ion transport will increase; higher osmotic potential will decrease airway surface liquid volume.
C) Sodium ion transport will decrease; lower osmotic potential will decrease airway surface liquid volume.
D) Sodium ion transport will decrease; lower osmotic potential will increase the airway surface liquid volume.
E) Sodium ion transport will be unaffected; lack of chloride transport still reduces osmotic potential and decreases the airway surface liquid volume. → e
34) When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
A) The cell will burst.
B) The cell membrane will lyse.
C) Plasmolysis will shrink the interior.
D) The cell will become flaccid.
E) The cell will become turgid. → e