1. In reference to skeletal muscle contraction, which of the following statements is false?

A. the size of the A band decreases.
B. the size of the H band decreases.
C. The size of the I band decreases.
D. Z lines are drawn closer to the M line.
E. The Z lines are drawn closer together.

2. One of the genetic myopathies is characterized by a defect in glycogenolysis. Which one of the following symptoms would be expected to characterize this disorder?

A. Presence of relatively short sarcomeres
B. Absence of voltage-gated Ca+2 channels
C. Ability to perform short durations of low-level muscle activity but inability to sustain high levels of muscle activity
D. Failure to propagate action potentials along motor neurons
E. Constant crossbridge cycling

3. Excitation-contraction coupling in skeletal muscle involves all the following events EXCEPT:

A. generation of end-plate potential.
B. binding of Calcium to myosin.
C. formation of cross-linkages between actin and myosin.
D. depolarization along transverse tubules.
E. hydrolysis of ATP to ADP.

4. The diagram below shows the Isometric point for muscle I and muscle II, which are the same size and made of the same type of muscle fibers. What conclusion (concerning muscle I and muscle II) would not be supported by the following diagram?

A. The action potential frequency innervating muscle II is greater than I.
B. Muscle II is innervated by fewer motor neurons than Muscle I.
C. Muscle II is at 145% of its muscle length and Muscle I is at 85%.
D. Contraction by Muscle I involves a smaller motor unit size than Muscle II.
E. Muscle fibers in Muscle I have a smaller diameter than those of Muscle II.

5. Which is true of Smooth muscle?

A. Phosphorylation is required to relax smooth muscle.
B. Calcium regulation of crossbridge cycling involves thick and thin filaments.
C. Gap junctions in smooth muscle are less important than those in skeletal muscle.
D. Contractions initiated by hormones are always inhibitory and those induced by neurotransmitters are always excitatory.
E. Calcium influx across the plasma membrane is not a mechanism by which contraction is initiated.

6. The latched state of smooth muscle contraction is important because:

A. it accelerated the extrusion of calcium from the cytoplasm.
B. it creates longer action potential durations by holding sodium channels open longer.
C. calcium is more tightly bound to calmodulin, which extends contraction times.
D. calcium is more weakly bound to calmodulin to speed relaxation.
E. ATP consumption is reduced.