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Question: Thin and thick filaments are organized into functional units called ________.
Choices:
myofibrils
myofilaments
T-tubules
sarcomeres
Question: During muscle contraction, the cross-bridge detaches when ________.
Choices:
the myosin head binds to an ADP molecule
the myosin head binds to an ATP molecule
calcium ions bind to troponin
calcium ions bind to actin
Question: Which element is important in directly triggering contraction?
Choices:
sodium (Na+)
calcium (Ca++)
potassium (K+)
chloride (Cl-)
Question: Which of the following properties is not common to all three muscle tissues?
Choices:
excitability
the need for ATP
at rest, uses shielding proteins to cover actinbinding sites
elasticity
Question: The correct order for the smallest to the largest unit of organization in muscle tissue is ________.
Choices:
fascicle, filament, muscle fiber, myofibril
filament, myofibril, muscle fiber, fascicle
muscle fiber, fascicle, filament, myofibril
myofibril, muscle fiber, filament, fascicle
Question: The cell membrane of a muscle fiber is called ________.
Choices:
myofibril
sarcolemma
sarcoplasm
myofilament
Question: Depolarization of the sarcolemma means ________.
Choices:
the inside of the membrane has become less negative as sodium ions accumulate
the outside of the membrane has become less negative as sodium ions accumulate
the inside of the membrane has become more negative as sodium ions accumulate
the sarcolemma has completely lost any electrical charge
Question: Muscle relaxation occurs when ________.
Choices:
calcium ions are actively transported out of the sarcoplasmic reticulum
calcium ions diffuse out of the sarcoplasmic reticulum
calcium ions are actively transported into the sarcoplasmic reticulum
calcium ions diffuse into the sarcoplasmic reticulum
Question: In relaxed muscle, the myosin-binding site on actin is blocked by ________.
Choices:
titin
troponin
myoglobin
tropomyosin
Question: According to the sliding filament model, binding sites on actin open when ________.
Choices:
creatine phosphate levels rise
ATP levels rise
acetylcholine levels rise
calcium ion levels rise
Question: Muscle that has a striped appearance is described as being ________.
Choices:
elastic
nonstriated
excitable
striated
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