PSIO 303 Unit 1 Quizzes Solved Correctly Latest Version 2025
Which of the following best describes what takes place when an ion channel opens?
A. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on the ATP
hydrolysis by the channel.
B. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on ion's
concentration gradient across the plasma membrane.
C. Ions flow through the channel in both directions but the rate of flow may be greater in one direction.
The rates of flow depend on both the ion's concentration gradient across the plasma membrane and the
membrane potential.
D. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on voltage
across the plasma membrane. - Answers C
Consider pancreatic beta cells that have been isolated and placed in culture medium. In an experiment,
the cells are deprived of oxygen for 8 hours, reducing the availability of cytoplasmic ATP almost to nil. A
scientist used an electrophysiology technique to measure the cell membrane potential (voltage across
the plasma membrane). Which of the statements best describes what she found when she compared
their membrane potential of oxygen-deprived cells to the membrane potential measured in untreated
(normal) cells?
A. Membrane potential was unchanged.
, B. Membrane potential was less negative. (The cells had depolarized)
C. Membrane potential was more negative. (The cells had hyperpolarized) - Answers B
Consider a cell that has normal cytoplasmic concentrations of sodium and potassium, immersed in a
solution that contains approximately 120 mM NaCl and 3 mM KCl. According to the Goldman equation,
which statement best describes the situation if the cell is found to have a membrane potential of +40
mV?
A. PNa is greater than PK
B. PNa and PCl both equal zero and PK is high
C. PK is greater than PNa but PCl equals zero
D. PK is greater than PNa - Answers A
Insulin receptors are integral membrane proteins found on the plasma membrane of several types of
cell. Which of the following statements best describes insulin receptors?
A. Insulin receptor protein does not have a hydrophobic region.
Which of the following best describes what takes place when an ion channel opens?
A. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on the ATP
hydrolysis by the channel.
B. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on ion's
concentration gradient across the plasma membrane.
C. Ions flow through the channel in both directions but the rate of flow may be greater in one direction.
The rates of flow depend on both the ion's concentration gradient across the plasma membrane and the
membrane potential.
D. Ions flow through the channel in one direction (a unidirectional flux) and the rate depends on voltage
across the plasma membrane. - Answers C
Consider pancreatic beta cells that have been isolated and placed in culture medium. In an experiment,
the cells are deprived of oxygen for 8 hours, reducing the availability of cytoplasmic ATP almost to nil. A
scientist used an electrophysiology technique to measure the cell membrane potential (voltage across
the plasma membrane). Which of the statements best describes what she found when she compared
their membrane potential of oxygen-deprived cells to the membrane potential measured in untreated
(normal) cells?
A. Membrane potential was unchanged.
, B. Membrane potential was less negative. (The cells had depolarized)
C. Membrane potential was more negative. (The cells had hyperpolarized) - Answers B
Consider a cell that has normal cytoplasmic concentrations of sodium and potassium, immersed in a
solution that contains approximately 120 mM NaCl and 3 mM KCl. According to the Goldman equation,
which statement best describes the situation if the cell is found to have a membrane potential of +40
mV?
A. PNa is greater than PK
B. PNa and PCl both equal zero and PK is high
C. PK is greater than PNa but PCl equals zero
D. PK is greater than PNa - Answers A
Insulin receptors are integral membrane proteins found on the plasma membrane of several types of
cell. Which of the following statements best describes insulin receptors?
A. Insulin receptor protein does not have a hydrophobic region.
