BIO 126 EXAM 3 QUESTIONS AND ANSWERS
During the course of muscle contraction, the potential energy stored in ATP is transferred to the
potential energy stored in _______. - CORRECT ANSWER✅✅the myosin head, the hydrolysis of ATP
causes the myosin head to change position, storing energy that will be used to contract the muscle.
The release of ______ ions from the sarcoplasmic reticulum is required for skeletal muscle contraction -
CORRECT ANSWER✅✅Calcium ions interact with proteins on the thin filament, resulting in the
exposure of the myosin-binding sites on the actin.
Myosin heads to _____, which they then pull and cause to slide toward the center of the sarcomere. -
CORRECT ANSWER✅✅Thin filaments. Myosin heads bind to thin filaments, release their bound ADP
and phosphate, and bend, sliding their thin filaments toward the center of the sarcomere.
Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is _____.
the pumping of calcium ions out of the cytoplasm and back into the sarcoplasmic reticulum
the release of myosin heads from the thin filament
thin filaments slide back to their relaxed positions
proteins on the thin filaments block actin's myosin-binding sites - CORRECT ANSWER✅✅the pumping
of calcium ions out of the cytoplasm and back into the sarcoplasmic reticulum
The thick filaments of sarcomeres are composed of ______. - CORRECT ANSWER✅✅myosin
The thin filaments of sarcomeres are mostly composed of ______. - CORRECT ANSWER✅✅actin
A single muscle cell is referred to as a _______. - CORRECT ANSWER✅✅muscle fiber
Which muscle type is involved in the function of the digestive tract and blood vessels? - CORRECT
ANSWER✅✅Smooth muscle functions in many systems of the body, including the digestive tract and
blood vessels
, How does cardiac muscle differ from the other types of muscle? - CORRECT ANSWER✅✅Only cardiac
muscle contains branched cells
True or false? Myofibrils are the alternating light-dark units that produce the banded appearance of
muscle fibers. - CORRECT ANSWER✅✅False. Sarcomeres are the alternating light-dark units that
produce the banded appearance of myofibrils, which are the strands that make up each muscle fiber.
Which molecules form the thick filaments of sarcomeres? - CORRECT ANSWER✅✅Myosin
Which of the following statements about the stimulation of muscle cells is true?
Calcium ions bind the actin-myosin complex to start the muscle contraction process.
Acetylcholine opens channels that allow calcium ions into the muscle cell.
Neurotransmitters are released into the synapse between two muscle cells.
An action potential in a muscle cell ultimately results in the release of calcium ions into the cell. -
CORRECT ANSWER✅✅An action potential in a muscle cell ultimately results in the release of calcium
ions into the cell. An action potential causes T tubules to depolarize, which stimulates the sarcoplasmic
reticulum to release calcium ions into the muscle cell.
Which step constitutes the power stroke of muscle contraction? - CORRECT ANSWER✅✅The phosphate
ion is released, and the myosin head moves back to its original position. The power stroke occurs when
the myosin head pivots, causing the actin filament to slide past the myosin filaments.
Which of the following interactions is the molecular basis of muscle contraction?
Sarcomeres and T tubules.
Myosin and thick filaments.
Myosin and thin filaments.
Troponin and tropomyosin. - CORRECT ANSWER✅✅myosin and thin filaments. The interaction of
myosin and thin filaments (actin) is the molecular basis of muscle contraction.
During the course of muscle contraction, the potential energy stored in ATP is transferred to the
potential energy stored in _______. - CORRECT ANSWER✅✅the myosin head, the hydrolysis of ATP
causes the myosin head to change position, storing energy that will be used to contract the muscle.
The release of ______ ions from the sarcoplasmic reticulum is required for skeletal muscle contraction -
CORRECT ANSWER✅✅Calcium ions interact with proteins on the thin filament, resulting in the
exposure of the myosin-binding sites on the actin.
Myosin heads to _____, which they then pull and cause to slide toward the center of the sarcomere. -
CORRECT ANSWER✅✅Thin filaments. Myosin heads bind to thin filaments, release their bound ADP
and phosphate, and bend, sliding their thin filaments toward the center of the sarcomere.
Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is _____.
the pumping of calcium ions out of the cytoplasm and back into the sarcoplasmic reticulum
the release of myosin heads from the thin filament
thin filaments slide back to their relaxed positions
proteins on the thin filaments block actin's myosin-binding sites - CORRECT ANSWER✅✅the pumping
of calcium ions out of the cytoplasm and back into the sarcoplasmic reticulum
The thick filaments of sarcomeres are composed of ______. - CORRECT ANSWER✅✅myosin
The thin filaments of sarcomeres are mostly composed of ______. - CORRECT ANSWER✅✅actin
A single muscle cell is referred to as a _______. - CORRECT ANSWER✅✅muscle fiber
Which muscle type is involved in the function of the digestive tract and blood vessels? - CORRECT
ANSWER✅✅Smooth muscle functions in many systems of the body, including the digestive tract and
blood vessels
, How does cardiac muscle differ from the other types of muscle? - CORRECT ANSWER✅✅Only cardiac
muscle contains branched cells
True or false? Myofibrils are the alternating light-dark units that produce the banded appearance of
muscle fibers. - CORRECT ANSWER✅✅False. Sarcomeres are the alternating light-dark units that
produce the banded appearance of myofibrils, which are the strands that make up each muscle fiber.
Which molecules form the thick filaments of sarcomeres? - CORRECT ANSWER✅✅Myosin
Which of the following statements about the stimulation of muscle cells is true?
Calcium ions bind the actin-myosin complex to start the muscle contraction process.
Acetylcholine opens channels that allow calcium ions into the muscle cell.
Neurotransmitters are released into the synapse between two muscle cells.
An action potential in a muscle cell ultimately results in the release of calcium ions into the cell. -
CORRECT ANSWER✅✅An action potential in a muscle cell ultimately results in the release of calcium
ions into the cell. An action potential causes T tubules to depolarize, which stimulates the sarcoplasmic
reticulum to release calcium ions into the muscle cell.
Which step constitutes the power stroke of muscle contraction? - CORRECT ANSWER✅✅The phosphate
ion is released, and the myosin head moves back to its original position. The power stroke occurs when
the myosin head pivots, causing the actin filament to slide past the myosin filaments.
Which of the following interactions is the molecular basis of muscle contraction?
Sarcomeres and T tubules.
Myosin and thick filaments.
Myosin and thin filaments.
Troponin and tropomyosin. - CORRECT ANSWER✅✅myosin and thin filaments. The interaction of
myosin and thin filaments (actin) is the molecular basis of muscle contraction.
