Download Muscle Contraction Web Practice

Muscle Contraction Web Practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. During the contraction of a vertebrate skeletal muscle fiber, calcium ions
a. break cross-bridges by acting as a cofactor in the hydrolysis of ATP.
b. bind with troponin, changing its shape so that the myosin-binding sites on actin are
exposed.
c. transmit action potentials from the motor neuron to the muscle fiber.
d. spread action potential through the T tubules.
e. reestablish the polarization of the plasma membrane following an action potential.
2. Which of the following changes occurs when a skeletal muscle fiber contracts?
a. The A bands shorten.
b. The I bands shrink.
c. The Z lines slide farther apart.
d. The thin filaments contract.
e. The thick filaments contract.
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3. A single muscle cell is referred to as a
a. myofibril.
b. muscle fiber.
c. muscle neuron.
d. sarcolemma.
e. sarcomere.
4. During the course of muscle contraction the potential energy stored in ATP is transferred to potential energy
stored in
a. the myosin head.
b. the myosin tail.
c. the thin filament.
d. actin.
e. the Z line.
5. Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is
a. the pumping of calcium ions out of the cytoplasm and back in the sarcoplasmic reticulum.
b. the release of myosin heads from the thin filament.
c. thin filaments slide back to their relaxed positions.
d. proteins on the thin filaments block actin's myosin-binding sites.
e. All of these events occur simultaneously.
Figure 36–2
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6. Which diagram(s) in Figure 36–2 show(s) muscles that are striated?
a. A and B
c. C
b. B
d. A and C
7. Where is the protein called actin located in the body?
a. ATP molecules
c. myosin filaments
b. thin filaments
d. acetylcholine neurotransmitters
8. What happens when the thin filaments in a muscle fiber slide over the thick filaments?
a. A muscle contracts.
b. A muscle relaxes.
c. A muscle both contracts and relaxes.
d. A muscle neither contracts nor relaxes.
9. According to the sliding-filament model, which of the following steps does NOT occur in muscle contraction?
a. Myosin and actin filaments come near each other.
b. Myosin filaments form cross-bridges with actin filaments.
c. Cross-bridges pull the two filaments past each other.
d. Actin filaments return to their original positions.
10. Which of the following is the largest?
a. myofibril
c. fascicle
b. myofilament
d. muscle fiber
11. Which muscle property involves the abaility to respond to nerve stimulation?
a. contractility
c. extensibility
b. excitability
d. elasticity
12. Whci of the following is a part of the thin filaments?
a. troponin
c. tropomyosin
b. sarcoplasmic reticulum
d. myosin binding sites
13. What specific action trigger a power stroke?
a. the release of inorganic phosphate from
c. the release of ADP from the myosin head.
the myosin head.
b. the hydrolization of the ATP.
d. the addition of a new ATP to the myosin
head.
14.
What specific action triggers the release of the myosin head from the actin?
a. the release of inorganic phosphate from
c.
the release of ADP from the myosin
the myosin head.
head.
b. the hydrolization of the ATP
d. the addition of a new ATP to the myosin
head.
Completion
Complete each statement.
15. What are the two types of myofilaments?
16. When the action potential goes down the motor neuron to the presynaptic bulb, a release of
________________ causes the vesicles full of acetylcholine to migrate to the cell membrane of the motor
neuron.
Short Answer
17. Each muscle fiber has an all-or-none response. How, then, can the strength of the muscle contraction vary?
18. How are the muscle fascia and sarcolemma similar in function?
19. The binding of the acetylcholine on the motor end plate (the sarcolemma of a muscle fiber) cause what to
occur?
Essay
20. Describe the roles of acetylcholine and the enzyme that destroys this chemical at the neuromuscular junction.
Muscle Contraction Web Practice
Answer Section
MULTIPLE CHOICE
1.
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11.
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14.
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B
B
B
A
A
D
36.2.1
B
36.2.2
A
36.2.2
D
36.2.2
C
B
B
A
D
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1
1
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I | F.1
1
I | F.1
1
I | F.1
1
I | F.1
1
1
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1
1
TOP:
TOP:
TOP:
DIF:
KEY:
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Web/CD Activity: Skeletal Muscle Structure
Web/CD Activity: Muscle Contraction
Web/CD Activity: Muscle Contraction
L2
REF: p. 926 | p. 927
application
L2
REF: p. 928
comprehension
L1
REF: p. 928
knowledge
L2
REF: p. 928
application
COMPLETION
15. ANS: actin & mysoin
PTS: 1
16. ANS: calcium
PTS: 1
SHORT ANSWER
17. ANS:
A muscle is made up of many muscle fibers. The strength of a muscle contraction varies depending upon the
total number of individual muscle fibers that contract.
PTS: 1
DIF: L3
REF: p. 929
OBJ: 36.2.2
NAT: I | F.1
KEY: analysis
18. ANS:
They are both covering (protection/holding things inside). The fascia on the actual muscle and the
sarcolemma along the muscle fiber (cell).
PTS: 1
19. ANS:
It cause a new stimulus to run across the sarcolemma. This stimulus goes down the T-tubules to stimulate the
release of Calium from the S.R.
PTS: 1
ESSAY
20. ANS:
Vesicles in the axon terminals of the motor neuron release acetylcholine. Acetylcholine molecules diffuse
across the synapse, producing an impulse in the cell membrane of the muscle fiber. The impulse causes the
release of calcium ions within the cell. A muscle fiber will remain in a state of contraction until the
production of acetylcholine stops. An enzyme, also produced at the neuromuscular junction, destroys
acetylcholine, permits the reabsorption of calcium ions into the muscle cell, and terminates the contraction.
PTS: 1
NAT: I | F.1
DIF: L2
REF: p. 929
KEY: comprehension
OBJ: 36.2.2