160 Chapter 6
- If a poison such as cyanide stopped the production of ATP,
which of the following transport processes would cease?
a. The movement of Na^1 out of a cell
b. Osmosis
c. The movement of K^1 out of a cell
d. All of these - Red blood cells crenate in
a. a hypotonic solution.
b. an isotonic solution.
c. a hypertonic solution.- Plasma has an osmolality of about 300 mOsm. The
osmolality of isotonic saline is equal to
a. 150 mOsm.
b. 300 mOsm.
c. 600 mOsm.
d. none of these. - Which of these statements comparing a 0.5 m NaCl solution
and a 1.0 m glucose solution is true?
a. They have the same osmolality.
b. They have the same osmotic pressure.
c. They are isotonic to each other.
d. All of these are true. - The most important diffusible ion in the establishment of the
membrane potential is
a. K^1. c. Ca^2 1.
b. Na^1. d. Cl^2. - Which of these statements regarding an increase in blood
osmolality is true?
a. It can occur as a result of dehydration.
b. It causes a decrease in blood osmotic pressure.
c. It is accompanied by a decrease in ADH secretion.
d. All of these are true. - In hyperkalemia, the resting membrane potential
a. moves farther from 0 millivolts.
b. moves closer to 0 millivolts.
c. remains unaffected.- Which of these statements about the Na^1 /K^1 pump is true?
a. Na^1 is actively transported into the cell.
b. K^1 is actively transported out of the cell.
c. An equal number of Na^1 and K^1 ions are transported
with each cycle of the pump.
d. The pumps are constantly active in all cells.- Which of these statements about carrier-mediated facilitated
diffusion is true?
a. It uses cellular ATP.
b. It is used for cellular uptake of blood glucose.
c. It is a form of active transport.
d. None of these are true.
12. Which of these is not an example of cotransport?
a. Movement of glucose and Na^1 through the apical
epithelial membrane in the intestinal epithelium
b. Movement of Na^1 and K^1 through the action of the Na^1 /
K^1 pumps
c. Movement of Na^1 and glucose across the kidney tubules
d. Movement of Na^1 into a cell while Ca^2 1 moves out
13. The resting membrane potential of a neuron or muscle cell is
a. equal to the potassium equilibrium potential.
b. equal to the sodium equilibrium potential.
c. somewhat less negative than the potassium equilibrium
potential.
d. somewhat more positive than the sodium equilibrium
potential.
e. not changed by stimulation.
14. Suppose that gated ion channels for Na^1 or Ca^2 1 opened
in the plasma membrane of a muscle cell. The membrane
potential of that cell would
a. move toward the equilibrium potential for that ion.
b. become less negative than the resting membrane potential.
c. move farther away from the potassium equilibrium
potential.
d. all of these.
15. Which of the following questions regarding second
messengers is false?
a. They are needed to mediate the action of nonpolar
regulatory molecules.
b. They are released from the plasma membrane into the
cytoplasm of cells.
c. They are produced in response to the binding of
regulatory molecules to receptors in the plasma
membrane.
d. They produce the intracellular actions of polar regulatory
molecules.
Test Your Understanding- Describe the conditions required to produce osmosis and
explain why osmosis occurs under these conditions. - Explain how simple diffusion can be distinguished from
facilitated diffusion and how active transport can be
distinguished from passive transport. - Compare the resting membrane potential of a neuron with
the potassium and sodium equilibrium potentials. Explain
how this comparison relates to the relative permeabilities of
the resting plasma membrane to these two ions. - Describe how the Na^1 /K^1 pumps contribute to the resting
membrane potential. Also, describe how the membrane
potential would be affected if (1) gated Na^1 channels were
to open, and (2) gated K^1 channels were to open. - Explain how the permeability of a membrane to glucose
and to water can be regulated by the insertion or removal of
carrier proteins, and give examples.