Chapter 13 Membrane Channels and Pumps 4 5 Multidrug resistance in tumor cells is A)due to the action of a membrane pump which transports small molecules out of the cells. B) the development of resistance to several drugs following an initial resistance to a single drug. C) caused by a mutation in the cystic fibrosis gene. D) a and b. E)All of the above. Ans:D Section:13.2 6 Which of the following is NOT correct concerning the ABC proteins? A) They undergo conformational changes upon ATP binding B) All are also members of the P-loop NTPase superfamily. C) The ATP-binding domains are referred to as ATP-binding cassettes. D) The substrate only binds after the ATP is bound. E)None of the above;they are all true statements. Ans:D Section:13.2 7 Membrane transporters that couple downhill flow of one species to the uphill flow of another species in the opposite direction are called A)antiporters. D All of the above. B) symporters. E) None of the above. c) exchangers. Ans:A Section:13.3 28.Ion channels A) can be selective. B) exist in open and closed states. C) in the open state often spontaneously convert into an inactivated state. D) a and b. E) a.b,and c. Ans:E Section:13.5 29.What are the similarities between sodium,potassium,and calcium ion channels? A)All allow passage of various ions. B) They contain homologous domains in the membrane spanning regions C) They all contain five peptides that combine to form the channel. D) All of the above. E)None of the above. Ans:B Section:13.4 30.As potassium moves through the ion channel,the associated water molecules A)are shed. D)All of the above. B) remain bound. E) None of the above. C)are rearranged around the ion. Ans:A Section:13.4Chapter 13 Membrane Channels and Pumps 4 5 Multidrug resistance in tumor cells is A) due to the action of a membrane pump which transports small molecules out of the cells. B) the development of resistance to several drugs following an initial resistance to a single drug. C) caused by a mutation in the cystic fibrosis gene. D) a and b. E) All of the above. Ans: D Section: 13.2 6 Which of the following is NOT correct concerning the ABC proteins? A) They undergo conformational changes upon ATP binding. B) All are also members of the P-loop NTPase superfamily. C) The ATP-binding domains are referred to as ATP-binding cassettes. D) The substrate only binds after the ATP is bound. E) None of the above; they are all true statements. Ans: D Section: 13.2 7 Membrane transporters that couple downhill flow of one species to the uphill flow of another species in the opposite direction are called A) antiporters. D) All of the above. B) symporters. E) None of the above. C) exchangers. Ans: A Section: 13.3 28. Ion channels A) can be selective. B) exist in open and closed states. C) in the open state often spontaneously convert into an inactivated state. D) a and b. E) a, b, and c. Ans: E Section: 13.5 29. What are the similarities between sodium, potassium, and calcium ion channels? A) All allow passage of various ions. B) They contain homologous domains in the membrane spanning regions. C) They all contain five peptides that combine to form the channel. D) All of the above. E) None of the above. Ans: B Section: 13.4 30. As potassium moves through the ion channel, the associated water molecules A) are shed. D) All of the above. B) remain bound. E) None of the above. C) are rearranged around the ion. Ans: A Section: 13.4