#1
What is the function of skeletal muscles in the body?
To produce movement
ExplanationSkeletal muscles generate force and motion by contracting and relaxing.
#2
Which of the following is NOT a structural component of a skeletal muscle?
Tendon
ExplanationTendons connect muscles to bones and are not part of the muscle structure itself.
#3
What is the role of acetylcholine in the neuromuscular junction?
To trigger muscle contraction
ExplanationAcetylcholine initiates the muscle contraction process by transmitting signals at the neuromuscular junction.
#4
What is the primary neurotransmitter released at the neuromuscular junction?
Acetylcholine
ExplanationAcetylcholine is the main neurotransmitter responsible for transmitting signals at the neuromuscular junction.
#5
What is the purpose of the motor end plate in the neuromuscular junction?
To propagate action potentials
ExplanationThe motor end plate facilitates the transmission of action potentials from neurons to muscle fibers.
#6
What is the name of the protein that covers the binding sites on actin molecules, preventing myosin from binding to them in a muscle at rest?
Tropomyosin
ExplanationTropomyosin acts as a barrier on actin, preventing myosin binding and muscle contraction at rest.
#7
Which of the following is a characteristic of fast-twitch muscle fibers?
Low myoglobin content
ExplanationFast-twitch muscle fibers have lower myoglobin levels, affecting their oxygen storage capacity.
#8
Which molecule binds to calcium ions to initiate muscle contraction?
Troponin
ExplanationTroponin binds to calcium ions, allowing the muscle contraction process to begin.
#9
What is the role of ATP in muscle contraction?
To bind to myosin heads and release them from actin
ExplanationATP provides energy for myosin-actin interactions, enabling muscle contraction.
#10
Which of the following is responsible for the rapid release of calcium ions into the muscle cell during muscle contraction?
Sarcoplasmic reticulum
ExplanationThe sarcoplasmic reticulum releases calcium ions, triggering muscle contraction.
#11
Which of the following statements about muscle fatigue is true?
It is the result of a buildup of lactic acid in the muscle
ExplanationAccumulation of lactic acid contributes to muscle fatigue during prolonged activity.
#12
During muscle contraction, what happens to the distance between the Z-lines in a sarcomere?
It decreases
ExplanationThe Z-lines in a sarcomere move closer together during muscle contraction.
#13
What is the role of calcium ions in muscle contraction?
To bind to troponin and remove the blocking action of tropomyosin
ExplanationCalcium ions bind to troponin, enabling the release of tropomyosin blockage and initiating muscle contraction.