Arrange the following list of biochemical events in the correct sequence.
(1) An action potential is conducted deep into the muscle fiber by the T tubule.
(2) Calcium ions bind to troponin.
(3) The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
(4) Calcium ions diffuse into the sarcoplasm around the myofibril.
(5) The troponin-tropomyosin complex moves exposing active sites.
A. 1, 5, 2, 3, 4
B. 1, 3, 4, 2, 5
C. 1, 2, 3, 4, 5
D. 1, 3, 2, 5, 4
E. 1, 4, 3, 2, 5
(
Question 2) T tubules
A. provide nutrients to the muscle fiber.
B. generate new muscle fibers.
C. conduct action potentials deep into the muscle cell.
D. release acetylcholine.
E. store calcium ions.
(
Question 3) Too much acetylcholinesterase causes
A. continuous stimulation of the muscle fiber.
B. rapid degradation of acetycholine.
C. voltage-gated calcium ion channels opening in the presynaptic terminal.
D. an increase in sodium uptake by the muscle fiber.
E. exocytosis of synaptic vesicles.
(
Question 4) Which of the following events occurs on the postsynaptic membrane?
A. acetylcholine production
B. rapid degradation of acetylcholine
C. release of neurotransmitter
D. neurotransmitter combines with a receptor molecule
E. release of calcium ions
(
Question 5) If sodium ions cannot enter a muscle fiber in response to a stimulus,
A. contraction cannot occur.
B. relaxation cannot occur.
C. sodium ions will be released from the sarcoplasmic reticulum instead.
D. the active sites are left exposed.
E. the action potential travels into the muscle anyway.
(
Question 6) T tubules are invaginations of the
A. sarcoplasmic reticulum.
B. sarcomere.
C. myofibril.
D. sarcoplasm.
E. sarcolemma.
(
Question 7) When an action potential reaches the presynaptic terminal,
A. calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.
B. acetylcholine moves into the presynaptic terminal.
C. a local potential is generated in the presynaptic terminal.
D. ligand-gated ion channels in the presynaptic terminal are opened.
E. nothing else happens.
(
Question 8) Lack of acetylcholinesterase in the synaptic cleft would result in
A. a decrease in acetylcholine production by the motor neuron.
B. continuous stimulation of the postsynaptic membrane.
C. rapid degradation of acetylcholine.
D. relaxation of the muscle.
E. continuous stimulation of the presynaptic membrane.
(
Question 9) Acetylcholine is released from the presynaptic terminal by the process of
A. exocytosis.
B. diffusion.
C. phagocytosis.
D. active transport.
E. endocytosis.
(
Question 10) Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in
A. hyperpolarization.
B. depolarization.
C. hypoplarization.
D. no change in membrane potential.
E. There is not enough information to predict the outcome.
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