Chapter 2-Potentials

1. Which of the following substances can pass through the intermolecular space of plasma membrane by simple diffusion?

A. Oxygen

B. Amino acid

C. Glucose

D. Sodium ion

E. Potassium ion

2. Which of the following statements is correct?

A. Sodium ion is always transported by active mechanism

B. The only mechanism for glucose transport is carrier-mediated transport at any places.

C. Nitrogen can pass through the cell membrane by simple diffusion.

D. Protein can pass through the protein-formed membrane channel

E. Entry of glucose into muscle cells requires the presence of sodium ion.

3. Which of the following descriptions about carrier-mediated transport is not correct?

A. It has saturation phenomenon
B. It has competitive inhibition
C. It is highly specific
D. It requires no metabolic energy
E. It has nothing to do with membrane protein

4. Bacteria enters the cells by

A. Simple diffusion

B. Carrier-mediated diffusion

C. Phagocytosis

D. Channel-mediated transport

E. Exocytosis

5. The resting potential of a neuron is mainly caused by

A. Inward diffusion of potassium ions

B. Outward diffusion of potassium ions

C. Inward diffusion of sodium ions

D. Outward diffusion of sodium ions

E. Active transport of sodium pump

6. Which of the following substances can block transmission at neuromuscular junction?

A. Atropine

B. Acetylcholine

C. Carbacol

D. Alpha-bungarotoxin

E. Physostigmine

7. Which of the following substances is mainly responsible for the depolarization stage of an action potential of a neuron?

A. Sodium ion

B. Calcium ion

C. Potassium ion

D. Chloride ion

E. Magnesium ion

8. Which of the following ions couples the excitation to the contraction of muscle cells?

A. Sodium ion

B. Calcium ion

C. Chloride ion

D. Potassium ion

E. Magnesium ion

9. Voltage-gated sodium channel of a neuron can be blocked by

A. Tetrodotoxin (TTX)

B. Tetraethylammomium (TEA)

C. Atropine

D. Cs

E. Varapamil

10. At resting condition, the neuronal membrane is mainly permeable to

A. K+

B. Na+

C. Ca2+

D. Cl-

E. Mg2+

11. The value of overshoot of a neuronal action potential is almost equal to

A. EK+

B. E Na+

C. E Ca2+

D. ECl-

E. E K+ E Na+

12. To initiate skeletal muscle contraction, Ca 2+ must bind to

A. Troponin C

B. Troponin T

C. Troponin I

D. Binding site of actin filament

E. Head of cross bridge of myosin filament

13. Excitation-contraction coupling of skeletal muscle is mediated by

A. ACh

B. Ca2+

C. Na+

D. K+

E. N-2 cholinergic receptor

14. Which of the following characteristics of an axon is more dependent on its diameter?

A. The magnitude of its resting potential

B. The duration of its refractory period

C. The conduction velocity of its action potential

D. The overshoot of its action potential

E. The activity of its sodium-potassium pump

15. Membrane excitability will be increased by the greatest amount by

A. Increasing extracellualr Na+

B. Decreasing extracellualr K+

C. Decreasing extracellualr Cl-

D. Decreasing extracelluarl Ca2+

E. Decreasing extracellualr H+

16. In a nerve, the magnitude of the action potential overshoot is normally a function of

A. Magnitude of the stimulus

B. Intracellular potassium concentration

C. Extracellular sodium concentration

D. Resting membrane potential

E. diameter of the axon

17. Which of the following words or phrases is most closely associated with an end-plate potential at the neuromuscular junction?

A. “All-or-none response”

B. Depolarization

C. Hyperpolarization

D. Resting membrane potential

E. Electrically excitable gates

18. The amount of force produced by skeletal muscle can be increased by

A. Increasing extracellular Mg2+

B. Decreasing extracellular Ca2+

C. Increasing the activity of acetylcholinesterase

D. Decreasing the interval between contractions

E. Increasing the preload beyond 3,9μm

19. Periodic hyperkalemic paralysis is characterized by high potassium concentration and muscle weakness. Which of the following is likely to cause muscle weakness as a result of increased extracellular potassium concentration?

A. Hyperpolarization of muscle cells and neurons

B. Inactivation sodium channels in muscle cells and motor neurons

C. Increased release of neurotransmitters from alpha motor neurons

D. Decreased potassium conductance in muscle cells or neurons

E. Increased duration of action potentials produced by alpha motor neurons

20. The membrane potential will be depolarize by the greatest amount if the membrane permeability increases for

A. Potassium

B. Sodium and potassium

C. Chloride

D. Potassium and chloride

E. Sodium