BIOL251 MODULE 6 EXAM REVIEW:
THE MUSCULAR SYSTEM| 50
QUESTIONS | PORTAGE LEARNING
1. Which of the following describes the functional unit of a skeletal muscle fiber?
A. The myofibril
B. The sarcolemma
C. The sarcoplasmic reticulum
D. The sarcomere
Answer: D
Conceptual Explanation: The sarcomere is the smallest functional, contractile unit of a
muscle fiber, extending from one Z-disc to the next.
2. During the sliding filament mechanism, which protein acts as a ‘molecular motor’ by pulling
on the thin filaments?
A. Myosin
B. Tropomyosin
C. Troponin
,D. Actin
Answer: A
Conceptual Explanation: Myosin heads bind to actin and use ATP energy to perform the
power stroke, pulling the thin filaments toward the M-line.
3. What is the specific role of calcium ions in muscle contraction?
A. Binding to tropomyosin to move it off the actin binding sites
B. Binding to troponin to expose myosin-binding sites on actin
C. Activating the sodium-potassium pump on the sarcolemma
D. Providing the energy needed for the myosin head power stroke
Answer: B
Conceptual Explanation: Calcium binds to troponin, which undergoes a conformational
change that moves tropomyosin away from the myosin-binding sites on the actin filament.
4. Which connective tissue layer surrounds an entire muscle?
A. Endomysium
B. Epimysium
C. Perimysium
D. Hypodermis
Answer: B
, Conceptual Explanation: The epimysium is the outermost layer of dense irregular
connective tissue that surrounds the whole muscle.
5. A motor unit is defined as:
A. A single motor neuron and all the muscle fibers it innervates
B. All the myofibrils within a single muscle cell
C. A single muscle fiber and all the neurons that innervate it
D. The junction between a motor neuron and the sarcolemma
Answer: A
Conceptual Explanation: A motor unit consists of one somatic motor neuron plus all the
skeletal muscle fibers it stimulates.
6. What is the neurotransmitter released at the neuromuscular junction?
A. Acetylcholine
B. Norepinephrine
C. Serotonin
D. Dopamine
Answer: A
Conceptual Explanation: Acetylcholine (ACh) is the specific neurotransmitter used by
somatic motor neurons to signal muscle contraction at the motor end plate.
THE MUSCULAR SYSTEM| 50
QUESTIONS | PORTAGE LEARNING
1. Which of the following describes the functional unit of a skeletal muscle fiber?
A. The myofibril
B. The sarcolemma
C. The sarcoplasmic reticulum
D. The sarcomere
Answer: D
Conceptual Explanation: The sarcomere is the smallest functional, contractile unit of a
muscle fiber, extending from one Z-disc to the next.
2. During the sliding filament mechanism, which protein acts as a ‘molecular motor’ by pulling
on the thin filaments?
A. Myosin
B. Tropomyosin
C. Troponin
,D. Actin
Answer: A
Conceptual Explanation: Myosin heads bind to actin and use ATP energy to perform the
power stroke, pulling the thin filaments toward the M-line.
3. What is the specific role of calcium ions in muscle contraction?
A. Binding to tropomyosin to move it off the actin binding sites
B. Binding to troponin to expose myosin-binding sites on actin
C. Activating the sodium-potassium pump on the sarcolemma
D. Providing the energy needed for the myosin head power stroke
Answer: B
Conceptual Explanation: Calcium binds to troponin, which undergoes a conformational
change that moves tropomyosin away from the myosin-binding sites on the actin filament.
4. Which connective tissue layer surrounds an entire muscle?
A. Endomysium
B. Epimysium
C. Perimysium
D. Hypodermis
Answer: B
, Conceptual Explanation: The epimysium is the outermost layer of dense irregular
connective tissue that surrounds the whole muscle.
5. A motor unit is defined as:
A. A single motor neuron and all the muscle fibers it innervates
B. All the myofibrils within a single muscle cell
C. A single muscle fiber and all the neurons that innervate it
D. The junction between a motor neuron and the sarcolemma
Answer: A
Conceptual Explanation: A motor unit consists of one somatic motor neuron plus all the
skeletal muscle fibers it stimulates.
6. What is the neurotransmitter released at the neuromuscular junction?
A. Acetylcholine
B. Norepinephrine
C. Serotonin
D. Dopamine
Answer: A
Conceptual Explanation: Acetylcholine (ACh) is the specific neurotransmitter used by
somatic motor neurons to signal muscle contraction at the motor end plate.
