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3 Written Questions

4 Matching Questions

  1. 20) The formulation of a model for a structure or for a process serves which of the following purposes?
    A) It asks a scientific question.
    B) It functions as a testable hypothesis.
    C) It records observations.
    D) It serves as a data point among results.
    E) It can only be arrived at after years of experimentation
  2. 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.
  3. 3) Singer and Nicolson's fluid mosaic model of the membrane proposed that
    A) membranes are a phospholipid bilayer.
    B) membranes are a phospholipid bilayer between two layers of hydrophilic proteins.
    C) membranes are a single layer of phospholipids and proteins.
    D) membranes consist of protein molecules embedded in a fluid bilayer of phospholipids.
    E) membranes consist of a mosaic of polysaccharides and proteins.
  4. 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.
  1. a a
  2. b d
  3. c b
  4. d c

5 Multiple Choice Questions

  1. e
  2. d
  3. c
  4. e
  5. a

5 True/False Questions

  1. 17) Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?
    A) transmembrane proteins
    B) integral proteins
    C) peripheral proteins
    D) integrins
    E) glycoproteins


  2. 38) What is the voltage across a membrane called?
    A) water potential
    B) chemical gradient
    C) membrane potential
    D) osmotic potential
    E) electrochemical gradient


  3. 40) The sodium-potassium pump is called an electrogenic pump because it
    A) pumps equal quantities of Na+ and K+ across the membrane.
    B) pumps hydrogen ions out of the cell.
    C) contributes to the membrane potential.
    D) ionizes sodium and potassium atoms.
    E) is used to drive the transport of other molecules against a concentration gradient


  4. 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.


  5. 44) Which of the following would increase the electrochemical potential across a membrane?
    A) a chloride channel
    B) a sucrose-proton cotransporter
    C) a proton pump
    D) a potassium channel
    E) both a proton pump and a potassium channel


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