Chapter 13 Membrane Channels and Pumps 3 7 The interconversion between two conformations of a transporter is sometimes referred to as Ans:eversion Section:13.2 8 Tetrodotoxin,isolated from puffer fish,binds tightly and specifically to channels in nerve cells. Ans:Na,sodium Section:13.4 9 The acetylcholine receptor is an example of a -gated channel. Ans:ligand Section:13.4 10 are an important class of channels that increase the rate at which water flows through membranes. Ans:Aquaporins Section:13.6 Multiple Choice Questions 1 A channel that opens in response to binding a particular molecule is called a channel. A) passive diffusion D) All of the above. B) symport E) None of the above. C) ligand-gated Ans:C Section 13.4 2 Channels that open in response to membrane depolarization are called channels A) voltage-gated D) All of the above. symport E) None of the above. C) ligand-gated Ans:A Section 13.4 3 When a molecule moves from a concentration of 10-M to 10-2M,is the process spontaneous,at equilibrium,or does it require an input of energy? A) at equilibrium D) All of the above B) input of energy required E) None of the above. spontaneous Ans:B Section:13.1 4 Which of the following is correct concerning the sarcoplasmic reticulum Ca2+ATPase? A)It is an example of an ABC transporter. B) It transports Ca2+from the sarcoplasmic reticulum into the cytoplasm. C) This P-type ATPase maintains a calcium ion concentration of approximately 0.1 uM in the cytosol and 1.5 uM in the sarcoplasmic reticulum D) One Ca2+is transported for each ATP hydrolyzed. E)None of the above. Ans:C Section:13.2Chapter 13 Membrane Channels and Pumps 3 7 The interconversion between two conformations of a transporter is sometimes referred to as __________________. Ans: eversion Section: 13.2 8 Tetrodotoxin, isolated from puffer fish, binds tightly and specifically to ___________ channels in nerve cells. Ans: Na + , sodium Section: 13.4 9 The acetylcholine receptor is an example of a ____________-gated channel. Ans: ligand Section: 13.4 10 ___________________ are an important class of channels that increase the rate at which water flows through membranes. Ans: Aquaporins Section: 13.6 Multiple Choice Questions 1 A channel that opens in response to binding a particular molecule is called a ________ channel. A) passive diffusion D) All of the above. B) symport E) None of the above. C) ligand-gated Ans: C Section 13.4 2 Channels that open in response to membrane depolarization are called __________ channels. A) voltage-gated D) All of the above. B) symport E) None of the above. C) ligand-gated Ans: A Section 13.4 3 When a molecule moves from a concentration of 10 4M to 10 2 M, is the process spontaneous, at equilibrium, or does it require an input of energy? A) at equilibrium D) All of the above. B) input of energy required E) None of the above. C) spontaneous Ans: B Section: 13.1 4 Which of the following is correct concerning the sarcoplasmic reticulum Ca 2+ ATPase? A) It is an example of an ABC transporter. B) It transports Ca 2+ from the sarcoplasmic reticulum into the cytoplasm. C) This P-type ATPase maintains a calcium ion concentration of approximately 0.1 M in the cytosol and 1.5 M in the sarcoplasmic reticulum. D) One Ca 2+ is transported for each ATP hydrolyzed. E) None of the above. Ans: C Section: 13.2