BIOL251 MODULE 10 EXAM REVIEW:
MUSCULAR SYSTEM PHYSIOLOGY| 50
QUESTIONS | PORTAGE LEARNING
1. During the cross-bridge cycle, what specific action triggers the ‘power stroke’?
A. The binding of ATP to the myosin head
B. The release of inorganic phosphate from the myosin head
C. The hydrolysis of ATP into ADP and inorganic phosphate
D. The binding of calcium to tropomyosin
Answer: B
Conceptual Explanation: The power stroke occurs when the inorganic phosphate (Pi)
generated from the previous ATP hydrolysis cycle is released from the myosin head,
causing the head to pivot.
2. Which protein acts as a calcium sensor in skeletal muscle fibers?
A. Troponin C
B. Tropomyosin
C. Calmodulin
,D. Actin
Answer: A
Conceptual Explanation: Troponin C is the specific subunit of the troponin complex that
binds to calcium ions, initiating the shift of tropomyosin.
3. In the neuromuscular junction, the enzyme acetylcholinesterase is primarily responsible
for:
A. Stimulating the release of acetylcholine from synaptic vesicles
B. Synthesizing acetylcholine from choline and acetyl-CoA
C. Opening voltage-gated sodium channels on the sarcolemma
D. Breaking down acetylcholine to prevent continuous muscle stimulation
Answer: D
Conceptual Explanation: Acetylcholinesterase breaks down acetylcholine into choline and
acetate in the synaptic cleft to terminate the signal and allow the muscle to relax.
4. A motor unit is defined as:
A. All the muscle fibers in a specific muscle belly
B. A single motor neuron and all the muscle fibers it innervates
C. The collection of all motor neurons that control a single limb
D. A single muscle fiber and all the neurons that touch it
, Answer: B
Conceptual Explanation: A motor unit consists of one somatic motor neuron and every
muscle fiber that receives a signal from its axon terminals.
5. Which of the following occurs during the latent period of a muscle twitch?
A. Calcium is being pumped back into the sarcoplasmic reticulum
B. Cross-bridges are actively cycling and generating tension
C. The action potential travels down the sarcolemma and T-tubules
D. The muscle decreases in length significantly
Answer: C
Conceptual Explanation: The latent period is the delay between the stimulus and the
onset of tension, during which excitation-contraction coupling (action potential
propagation and Ca2+ release) occurs.
6. What is the primary role of Creatine Phosphate in muscle metabolism?
A. To store oxygen for use during aerobic respiration
B. To facilitate the transport of glucose into the sarcoplasm
C. To provide a rapid source of phosphate groups to replenish ATP
D. To catalyze the breakdown of glycogen into lactic acid
Answer: C
MUSCULAR SYSTEM PHYSIOLOGY| 50
QUESTIONS | PORTAGE LEARNING
1. During the cross-bridge cycle, what specific action triggers the ‘power stroke’?
A. The binding of ATP to the myosin head
B. The release of inorganic phosphate from the myosin head
C. The hydrolysis of ATP into ADP and inorganic phosphate
D. The binding of calcium to tropomyosin
Answer: B
Conceptual Explanation: The power stroke occurs when the inorganic phosphate (Pi)
generated from the previous ATP hydrolysis cycle is released from the myosin head,
causing the head to pivot.
2. Which protein acts as a calcium sensor in skeletal muscle fibers?
A. Troponin C
B. Tropomyosin
C. Calmodulin
,D. Actin
Answer: A
Conceptual Explanation: Troponin C is the specific subunit of the troponin complex that
binds to calcium ions, initiating the shift of tropomyosin.
3. In the neuromuscular junction, the enzyme acetylcholinesterase is primarily responsible
for:
A. Stimulating the release of acetylcholine from synaptic vesicles
B. Synthesizing acetylcholine from choline and acetyl-CoA
C. Opening voltage-gated sodium channels on the sarcolemma
D. Breaking down acetylcholine to prevent continuous muscle stimulation
Answer: D
Conceptual Explanation: Acetylcholinesterase breaks down acetylcholine into choline and
acetate in the synaptic cleft to terminate the signal and allow the muscle to relax.
4. A motor unit is defined as:
A. All the muscle fibers in a specific muscle belly
B. A single motor neuron and all the muscle fibers it innervates
C. The collection of all motor neurons that control a single limb
D. A single muscle fiber and all the neurons that touch it
, Answer: B
Conceptual Explanation: A motor unit consists of one somatic motor neuron and every
muscle fiber that receives a signal from its axon terminals.
5. Which of the following occurs during the latent period of a muscle twitch?
A. Calcium is being pumped back into the sarcoplasmic reticulum
B. Cross-bridges are actively cycling and generating tension
C. The action potential travels down the sarcolemma and T-tubules
D. The muscle decreases in length significantly
Answer: C
Conceptual Explanation: The latent period is the delay between the stimulus and the
onset of tension, during which excitation-contraction coupling (action potential
propagation and Ca2+ release) occurs.
6. What is the primary role of Creatine Phosphate in muscle metabolism?
A. To store oxygen for use during aerobic respiration
B. To facilitate the transport of glucose into the sarcoplasm
C. To provide a rapid source of phosphate groups to replenish ATP
D. To catalyze the breakdown of glycogen into lactic acid
Answer: C
