Pretest Chapter 9
1) Which of the following is a recognized function of skeletal muscle?
A) produce movement
B) maintain posture
C) maintain body temperature
D) guard body entrances and exits
E) all of the above
2) Which of the following statements is incorrect?
A) The contractions of skeletal muscles pull on tendons and move bones of the skeleton.
B) Skeletal muscles store nutrient reserves.
C) Skeletal muscles are responsible for the pumping action of the heart.
D) Skeletal muscles support the weight of some internal organs.
E) Skeletal muscle contractions help maintain body temperature.
3) The dense layer of connective tissue that surrounds an entire skeletal muscle is the
A) tendon.
B) epimysium.
C) endomysium.
D) perimysium.
E) fascicle.
4) Nerves and blood vessels that service the muscle fibers are located in the connective tissues of
the
A) endomysium.
B) perimysium.
C) sarcolemma.
D) sarcomere.
E) myofibrils.
5) The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent
muscle fibers together is the
A) endomysium.
B) perimysium.
C) epimysium.
D) superficial fascia.
E) periosteum.
6) The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone
is called a(n)
A) fascicle.
B) tendon.
C) ligament.
D) epimysium.
E) myofibril.
7) Muscle fibers differ from "typical cells" in that muscle fibers
A) lack a plasma membrane.
B) have many nuclei.
C) are very small.
D) lack mitochondria.
E) both B and C
8) The advantage of having many nuclei in a skeletal muscle fiber is
A) the ability to contract.
B) the ability to produce more ATP with little oxygen.
C) the ability to store extra DNA for metabolism.
D) the ability to produce large amounts of the muscle proteins needed for growth and repair.
E) both C and D
9) The plasma membrane of skeletal muscle is called the
A) sarcolemma.
B) sarcomere.
C) sarcosome.
D) sarcoplasmic reticulum.
E) sarcoplasm.
10) Which of the following best describes the term sarcomere?
A) protein that accounts for elasticity of resting muscle
B) repeating unit of striated myofibrils
C) storage site for calcium ions
D) thin filaments are anchored here
E) largely made of myosin molecules
11) Which of the following best describes the term sarcoplasmic reticulum?
A) protein that accounts for elasticity of resting muscle
B) repeating unit of striated myofibrils
C) storage and release site for calcium ions
D) thin filaments are anchored here
E) largely made of myosin molecules
12) The repeating unit of a skeletal muscle fiber is the
A) sarcolemma.
B) sarcomere.
C) sarcoplasmic reticulum.
D) myofibril.
E) myofilament.
13) Interactions between actin and myosin filaments of the sarcomere are responsible for
A) muscle fatigue.
B) the conduction of neural stimulation to the muscle fiber.
C) muscle contraction.
D) muscle relaxation.
E) the striped appearance of skeletal muscle.
14) In a sarcomere, thick filaments are linked laterally by proteins of the
A) Z line.
B) M line.
C) H band.
D) A band.
E) I band.
15) Which of the following best describes the term Z line?
A) protein that accounts for elasticity of resting muscle
B) repeating unit of striated myofibrils
C) storage site for calcium ions
D) thin filaments are anchored here
E) largely made of myosin molecules
16) The region of the sarcomere containing the thick filaments is the
A) Z line.
B) M line.
C) H band.
D) A band.
E) I band.
17) The region of the sarcomere that always contains thin filaments is the
A) Z line.
B) M line.
C) H band.
D) A band.
E) I band.
18) The area in the center of the A band that contains no thin filaments is the
A) Z line.
B) M line.
C) H band.
D) I band.
E) zone of overlap.
19) Each thin filament consists of
A) two protein strands coiled helically around each other.
B) chains of myosin molecules.
C) six molecules coiled into a helical structure.
D) a rod-shaped structure with "heads" projecting from each end.
E) a double strand of myosin molecules.
20) The skeletal muscle complex known as the triad consists of
A) actin, myosin, and filaments.
B) a transverse tubule and two terminal cisternae.
C) filaments, myofibrils, and sarcomeres.
D) A bands, H bands, and I bands.
E) actin, myosin, and sarcomeres.
21) Cross-bridges are portions of
A) actin molecules.
B) myosin molecules.
C) troponin molecules.
D) tropomyosin molecules.
E) calcium ions.
22) At rest, active sites on the actin are blocked by
A) myosin molecules.
B) troponin molecules.
C) tropomyosin molecules.
D) calcium ions.
E) ATP molecules.
23) At rest, the tropomyosin molecule is held in place by
A) actin molecules.
B) myosin molecules.
C) troponin molecules.
D) ATP molecules.
E) calcium ions.
24) Each skeletal muscle fiber is controlled by a motor neuron at a single
A) synaptic knob.
B) sarcomere.
C) neuromuscular junction.
D) synaptic cleft.
E) transverse tubule.
25) The narrow space between the synaptic terminal and the muscle fiber is the
A) synaptic knob.
B) motor end plate.
C) motor unit.
D) synaptic cleft.
E) M line.
26) Receptors for acetylcholine are located on the
A) synaptic knob.
B) motor end plate.
C) sarcomere.
D) synaptic cleft.
E) transverse tubule.
27) The action potential is conducted into a skeletal muscle fiber by
A) motor end plates.
B) neuromuscular junctions.
C) transverse tubules.
D) triads.
E) sarcoplasmic reticulum.
28) Active sites on the actin become available for binding after
A) actin binds to troponin.
B) troponin binds to tropomyosin.
C) calcium binds to troponin.
D) calcium binds to tropomyosin.
E) myosin binds to troponin.
29) In response to action potentials arriving along the transverse tubules, the sarcoplasmic
reticulum releases
A) acetylcholine.
B) sodium ions.
C) potassium ions.
D) calcium ions.
E) hydrogen ions.
30) Which of the following acts as an ATPase during the contraction cycle of muscle?
A) actin molecules
B) troponin molecules
C) tropomyosin molecules
D) the head portion of the myosin molecule
E) the tail portion of the myosin molecule
31) The most important factor in decreasing the intracellular concentration of calcium ion after
contraction is
A) active transport of calcium across the sarcolemma.
B) active transport of calcium into the sarcoplasmic reticulum.
C) active transport of calcium into the synaptic cleft.
D) diffusion of calcium out of the cell.
E) diffusion of calcium into the sarcoplasmic reticulum.
32) Which of the following become connected by myosin cross-bridges during muscle
contraction?
A) thin filaments and thick filaments
B) thick filaments and titin filaments
C) z disks and actin filaments
D) thick filaments and t-tubules
E) thin filaments and t-tubules
33) When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually
increases to a steady maximum tension. This is called
A) incomplete tetanus.
B) complete tetanus.
C) a twitch.
D) wave summation.
E) recruitment.
34) A muscle producing tension that peaks and falls at intermediate stimulus rates is said to be in
A) incomplete tetanus.
B) complete tetanus.
C) treppe.
D) wave summation.
E) recruitment.
35) If a second stimulus arrives before the relaxation phase has ended, a second, more powerful
contraction occurs. This is called
A) incomplete tetanus.
B) complete tetanus.
C) treppe.
D) wave summation.
E) recruitment.
36) The increase in muscle tension that is produced by increasing the number of active motor
units is called
A) incomplete tetanus.
B) complete tetanus.
C) treppe.
D) wave summation.
E) recruitment.
37) The type of contraction in which the muscle fibers do not shorten is called
A) tetany.
B) treppe.
C) concentric.
D) isotonic.
E) isometric.
38) Creatine phosphate
A) is produced by the process of anaerobic respiration.
B) can replace ATP in binding to myosin molecules during contraction.
C) acts as an energy reserve in muscle tissue.
D) is only formed during strenuous exercise.
E) cannot transfer its phosphate group to ADP.
39) During anaerobic glycolysis
A) ATP is produced.
B) pyruvic acid is produced.
C) oxygen is not consumed.
D) all of the above
E) B and C only
40) During the recovery period following exercise, all of the following are true, except
A) lactic acid is removed from muscle cells.
B) the muscle actively produces ATP.
C) muscle fibers are unable to contract.
D) oxygen is consumed at above the resting rate.
E) heat is generated.
41) Fast fibers
A) have low resistance to fatigue.
B) rely on aerobic metabolism.
C) have many mitochondria.
D) have twitches with a very brief contraction phase.
E) both A and D
42) The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
A) fast
B) slow
C) intermediate
D) anaerobic
E) high-density
43) Muscular force can be adjusted to match different loads by
A) varying the frequency of action potentials in motor neurons
B) recruiting larger motor units
C) recruiting more motor units
D) A, B, and C
E) None of the above muscle contraction is all-or-none.
44) During activities requiring aerobic endurance
A) glycogen and glycolysis are the primary sources of reserve energy.
B) oxygen debts are common.
C) most of the muscle's energy is produced in mitochondria.
D) fatigue occurs in a few minutes.
E) oxygen is not required.
45) Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in
response to
A) repeated, exhaustive stimulation.
B) sustained low levels of muscle activity.
C) high amounts of oxygen.
D) increased levels of testosterone.
E) prolonged periods of inactivity.
46) When a skeletal muscle fiber contracts,
A) the H bands and I bands get smaller.
B) the zones of overlap get larger.
C) the Z lines get closer together.
D) the width of the A band remains constant.
E) all of the above
47) Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten,
the muscle fiber
A) lengthens.
B) shortens.
C) strengthens.
D) weakens.
E) not enough information to say
48) The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the
neurotransmitter
A) epinephrine.
B) norepinephrine.
C) acetylcholine.
D) antidiuretic hormone.
E) all of the above
49) Which statement about excitation-contraction coupling is incorrect?
A) Calcium ion is released from the transverse tubule.
B) Calcium ion is released from the sarcoplasmic reticulum.
C) Tropomyosin moves to expose myosin binding sites on actin.
D) Troponin binds calcium ion and signals tropomyosin to move.
E) Relaxation requires uptake of calcium ion by the sarcoplasmic reticulum.
50) Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria
are characteristics of
A) slow fibers.
B) intermediate fibers.
C) fast fibers.
D) red muscles.
E) fatty muscles.
51) When contraction occurs,
A) the H bands get smaller.
B) the Z lines move closer together.
C) the width of the A band remains constant.
D) the I bands get smaller.
E) all of the above
52) In rigor mortis
A) the myosin heads are attached to actin.
B) ATP is depleted.
C) muscles are inextensible.
D) cross-bridge cycling is absent.
E) all of the above
53) The following is a list of the events that occur during a muscle contraction.
1.
2.
3.
4.
5.
6.
Myosin cross-bridges bind to the actin.
The free myosin head splits ATP.
Calcium ion is released from the sarcoplasmic reticulum.
The myosin head pivots toward the center of the sarcomere.
Calcium ion binds to troponin.
The myosin head binds an ATP molecule and detaches from the actin.
The correct sequence of these events is
A) 1, 3, 5, 4, 6, 2.
B) 5, 1, 4, 6, 2, 3.
C) 3, 5, 1, 2, 4, 6.
D) 3, 5, 1, 4, 6, 2.
E) 1, 4, 6, 2, 3, 5.
54) After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic
reticulum into the sarcoplasm. This results in a condition known as
A) tetany.
B) treppe.
C) depolarization.
D) rigor mortis.
E) oxygen debt.
55) How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
A) It would make the muscles less excitable.
B) It would produce muscle weakness.
C) It would cause spastic paralysis (muscles are contracted and unable to relax).
D) It would cause flaccid paralysis (muscles are relaxed and unable to contract).
E) It would have little effect on skeletal muscles.
56) When acetylcholine binds to receptors at the motor end plate, the end plate membrane
becomes
A) more permeable to sodium ions.
B) less permeable to sodium ions.
C) more permeable to calcium ions.
D) less permeable to potassium ions.
E) repolarized.
57) Triggering of the muscle action potential occurs after
A) acetylcholine binds to chemically gated channels in the end plate membrane.
B) acetylcholinesterase binds to receptors on the end plate.
C) calcium ion binds to channels on the end plate.
D) the nerve action potential jumps across the neuromuscular junction.
E) Any of the above can produce an action potential in the muscle cell.
58) How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal
muscle?
A) It would make the muscles more excitable.
B) It would produce uncontrolled muscle spasms.
C) It would cause spastic paralysis (muscles are contracted and unable to relax).
D) It would cause flaccid paralysis (muscles are relaxed and unable to contract).
E) It would have little effect on skeletal muscles.
59) Synaptic vesicles containing neurotransmitters are released by ________ when the action
potential arrives.
A) endocytosis
B) apoptosis
C) exocytosis
D) hydrolysis
E) sodium
60) The muscle weakness of myasthenia gravis results from
A) insufficient acetylcholine release from presynaptic vesicles.
B) loss of acetylcholine receptors in the end-plate membrane.
C) the motor neuron action potential being too small to shock the muscle fibers.
D) excessive acetylcholinesterase that destroys the neurotransmitter.
E) All of the above probably contribute to the weakness.
61) Which of the following best describes the term muscle origin?
A) broad tendon sheet
B) connective tissue that surrounds a single muscle fiber
C) tendon attachment that doesn't move
D) tendon attachment that moves
E) connective tissue that surrounds an entire muscle
62) What is released from the structure labeled "9"?
A) sarcoplasm
B) acetylcholine
C) protein
D) calcium ions
E) acetylcholinesterase
63) Identify the structure labeled "1."
A) mitochondria
B) glycogen
C) ATP
D) myofibril
E) synaptic vesicle
64) Where would calcium ion be predominately found?
A) 1
B) 2
C) 4
D) 8
E) 9
65) What physiological process occurs in the structure labeled "7"?
A) release of neurotransmitter
B) conduction of the action potential into the cell interior
C) activity of acetylcholinesterase
D) release of protein into the muscle fiber
E) the sliding filament theory
66) Where are the myosin molecules located?
A) 4
B) 5
C) 6
D) 7
E) 8
67) Which structure contains the motor end plate?
A) 1
B) 2
C) 3
D) 5
E) 8
68) Which structure actively pumps calcium ions out of the sarcoplasm to produce relaxation?
A) 6
B) 7
C) 1
D) 3
E) 2
109) Which of the following are found in the structure labeled "3"?
A) actin
B) myosin
C) titin
D) tropomyosin
E) all of the above
Answer: E
Diff: 2
Skill: Level 2 Questions: Reviewing Concepts
110) Identify the structure where ATP is produced.
A) 6
B) 7
C) 1
D) 3
E) 2
Answer: C
Diff: 2
Skill: Level 2 Questions: Reviewing Concepts
111) Where is ATP is consumed?
A) 1
B) 2
C) 3
D) 6
E) 3 and 6
Answer: E
Diff: 2
Skill: Level 2 Questions: Reviewing Concepts