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5 Written questions

5 Matching questions

  1. True or false? Osmosis is a type of diffusion.
  2. Which of the following statements is true about the net movement of an ion across a membrane by passive diffusion through a membrane channel?

    a) The charge on the other side of the membrane is generally the opposite of the ion's charge.

    b) There is a higher concentration of ions on the side of the membrane toward which the ion diffuses.

    c) For every ion that diffuses through the membrane, a different ion diffuses in the opposite direction.

    d) The cell expends energy as the ion passes through the membrane.
  3. What name is given to the process by which water crosses a selectively permeable membrane?

    a) osmosis
    b) diffusion
    c) pinocytosis
    d) phagocytosis
    e) passive transport
  4. True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
  5. The movement of molecules through a plasma membrane channel protein is always _____.

    a) toward the inside of the cell

    b) down the molecule's concentration gradient

    c) against the molecule's concentration gradient

    d) "paid for" by an expenditure of cellular energy
  1. a a) osmosis (Osmosis is the passive transport of water.)
  2. b c) against the molecule's concentration gradient
  3. c True (Osmosis is the diffusion of water across a selectively permeable membrane.)
  4. d a) The charge on the other side of the membrane is generally the opposite of the ion's charge.

    (Ions tend to move toward regions of unlike charge.)
  5. e True (The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.)

5 Multiple choice questions

  1. c) Amphipathic nature
  2. a) Solution A: 1.4% (m/v) starch (The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.)
  3. b) The polarity of membrane phospholipids
  4. a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
  5. a) Transporter

    (The GLUT-1 transporter assists the diffusion of glucose through the membrane.)

5 True/False questions

  1. True or false? During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell.False
    (The sodium-potassium pump maintains a state in which the concentration of sodium is low inside the cell relative to the outside and the concentration of potassium is high inside the cell relative to the outside; thus, three sodium ions are pumped out of the cell and two potassium ions are pumped into the cell against the electrochemical gradient.)

          

  2. True or false? Active transport differs from passive transport in that active transport does not require an input of energy.False
    (The sodium-potassium pump maintains a state in which the concentration of sodium is low inside the cell relative to the outside and the concentration of potassium is high inside the cell relative to the outside; thus, three sodium ions are pumped out of the cell and two potassium ions are pumped into the cell against the electrochemical gradient.)

          

  3. Lipid vesicles are formed so that they contain pure water. If these vesicles are transferred to a solution that contains a rather high concentration of solutes, what will be the net direction of water movement?

    a) It will not move at all.

    b) It depends on what solute is dissolved in the exterior solution.

    c) It will move out of the vesicles.

    d) It will move into the vesicles.
    a) Hypotonic (The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst.)

          

  4. If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

    a) Hypotonic
    b) Hypertonic
    c) Osmotic
    d) Isotonic
    a) Hypotonic (The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst.)

          

  5. A semipermeable membrane is placed between the following solutions. Which solution will increase in volume?

    a) Solution C: 9% (m/v) NaCl
    b) Solution D: 12.4% (m/v) NaCl
    a) Solution A: 1.4% (m/v) starch (The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.)