Portage Learning | BIOD 151 — Essential Human Anatomy & Physiology I |
Module 5 Exam — A&P I | Muscular System · Origin & Insertion · Innervation ·
Contraction | 2026 Update | PSI · Respondus LockDown Browser | 100 Points ·
60 Minutes
1. What is the specialized plasma membrane of a muscle cell called?
A. Sarcoplasmic reticulum
B. Sarcolemma
C. Perimysium
D. Myofibril
Answer: B
Rationale: The sarcolemma is the specific name for the plasma membrane of a muscle
fiber.
2. Which connective tissue layer surrounds an entire muscle?
A. Epimysium
B. Perimysium
C. Endomysium
D. Deep fascia
Answer: A
Rationale: The epimysium is the outermost layer of connective tissue that wraps the entire
muscle.
,3. A sarcomere is the region between two ________.
A. M-lines
B. H-zones
C. Z-discs
D. I-bands
Answer: C
Rationale: A sarcomere, the functional unit of a muscle fiber, is defined as the distance
between two consecutive Z-discs.
4. Which protein makes up the thick filaments of a myofibril?
A. Actin
B. Troponin
C. Myosin
D. Tropomyosin
Answer: C
Rationale: Thick filaments are composed of the protein myosin.
5. What is the function of the sarcoplasmic reticulum (SR) in muscle
contraction?
A. To generate ATP
B. To conduct action potentials
C. To store and release calcium ions
D. To synthesize myosin
Answer: C
Rationale: The SR is a specialized endoplasmic reticulum that regulates intracellular
calcium levels.
, 6. Which neurotransmitter is released at the neuromuscular junction to initiate
contraction?
A. Acetylcholine
B. Serotonin
C. Dopamine
D. Norepinephrine
Answer: A
Rationale: Acetylcholine (ACh) is the neurotransmitter used by motor neurons to signal
muscle contraction.
7. During the sliding filament model, which of the following shortens?
A. A-band
B. I-band
C. Actin filaments
D. Myosin filaments
Answer: B
Rationale: As filaments slide, the I-bands and H-zones shorten, while the A-band remains
the same length.
8. What molecule must bind to the myosin head to cause it to detach from
actin?
A. ATP
B. Calcium
C. ADP
D. Phosphate
Answer: A
Rationale: The binding of a new ATP molecule causes the myosin head to release its grip
on the actin filament.
Module 5 Exam — A&P I | Muscular System · Origin & Insertion · Innervation ·
Contraction | 2026 Update | PSI · Respondus LockDown Browser | 100 Points ·
60 Minutes
1. What is the specialized plasma membrane of a muscle cell called?
A. Sarcoplasmic reticulum
B. Sarcolemma
C. Perimysium
D. Myofibril
Answer: B
Rationale: The sarcolemma is the specific name for the plasma membrane of a muscle
fiber.
2. Which connective tissue layer surrounds an entire muscle?
A. Epimysium
B. Perimysium
C. Endomysium
D. Deep fascia
Answer: A
Rationale: The epimysium is the outermost layer of connective tissue that wraps the entire
muscle.
,3. A sarcomere is the region between two ________.
A. M-lines
B. H-zones
C. Z-discs
D. I-bands
Answer: C
Rationale: A sarcomere, the functional unit of a muscle fiber, is defined as the distance
between two consecutive Z-discs.
4. Which protein makes up the thick filaments of a myofibril?
A. Actin
B. Troponin
C. Myosin
D. Tropomyosin
Answer: C
Rationale: Thick filaments are composed of the protein myosin.
5. What is the function of the sarcoplasmic reticulum (SR) in muscle
contraction?
A. To generate ATP
B. To conduct action potentials
C. To store and release calcium ions
D. To synthesize myosin
Answer: C
Rationale: The SR is a specialized endoplasmic reticulum that regulates intracellular
calcium levels.
, 6. Which neurotransmitter is released at the neuromuscular junction to initiate
contraction?
A. Acetylcholine
B. Serotonin
C. Dopamine
D. Norepinephrine
Answer: A
Rationale: Acetylcholine (ACh) is the neurotransmitter used by motor neurons to signal
muscle contraction.
7. During the sliding filament model, which of the following shortens?
A. A-band
B. I-band
C. Actin filaments
D. Myosin filaments
Answer: B
Rationale: As filaments slide, the I-bands and H-zones shorten, while the A-band remains
the same length.
8. What molecule must bind to the myosin head to cause it to detach from
actin?
A. ATP
B. Calcium
C. ADP
D. Phosphate
Answer: A
Rationale: The binding of a new ATP molecule causes the myosin head to release its grip
on the actin filament.
