,BIOD151/BIOD 151 Module 5 Exam | Essential Human
Anatomy & Physiology I with Lab | Portage Learning | Q & A |
2026/2027 Edition (PDF)
1. Which of the following statements about muscle tissue types is TRUE?
A) Skeletal muscle is under involuntary control
B) Cardiac muscle is striated and involuntary
C) Smooth muscle is striated and voluntary
D) Cardiac muscle is non-striated and involuntary
Correct Answer: Cardiac muscle is striated and involuntary
Rationale: Cardiac muscle is striated like skeletal muscle but is under involuntary control, meaning it
contracts without conscious thought. Smooth muscle is non-striated and involuntary, while skeletal
muscle is striated and voluntary.
2. What percentage of our total body weight does skeletal muscle tissue make up?
A) 20%
B) 30%
C) 40%
D) 50%
Correct Answer: 40%
Rationale: Skeletal muscle tissue accounts for approximately 40% of our total body weight. This makes it
the most abundant tissue type in the body, reflecting its crucial role in movement, posture, and heat
production.
3. What is the functional contractile unit of a skeletal muscle fiber?
A) Myofibril
B) Sarcomere
,C) Myosin filament
D) Actin filament
Correct Answer: Sarcomere
Rationale: The sarcomere is the basic functional unit of a skeletal muscle fiber, extending from one Z line
to the next. It contains overlapping thick (myosin) and thin (actin) filaments whose sliding interaction
produces muscle contraction.
4. Which of the following correctly describes the arrangement of filaments within a sarcomere?
A) Thick filaments are composed of actin; thin filaments are composed of myosin
B) Thick filaments are composed of myosin; thin filaments are composed of actin
C) Both thick and thin filaments are composed of myosin
D) Both thick and thin filaments are composed of actin
Correct Answer: Thick filaments are composed of myosin; thin filaments are composed of actin
Rationale: Sarcomeres contain two types of protein filaments: thick filaments made from myosin and
thin filaments made from actin. During contraction, these filaments slide past one another, shortening
the sarcomere.
5. What happens to the Z lines of a sarcomere during muscle contraction?
A) They move farther apart
B) They move closer together toward the M line
C) They remain in the same position
D) They disappear completely
Correct Answer: They move closer together toward the M line
, Rationale: When a muscle contracts, the Z lines move closer together toward the M line as the
sarcomere shortens. This occurs because the actin filaments slide past the myosin filaments, reducing
the distance between adjacent Z lines.
6. Which band of the sarcomere appears light when stained because it contains only thin filaments?
A) A band
B) H zone
C) I band
D) M line
Correct Answer: I band
Rationale: The I band appears light when stained because it contains only thin (actin) filaments. In
contrast, the A band contains both thick and thin filaments and stains darker.
7. What is the role of acetylcholine at the neuromuscular junction?
A) To break down the motor nerve ending
B) To bind to receptors on the muscle fiber and trigger sodium channels to open
C) To directly cause the muscle fiber to contract
D) To prevent calcium from entering the muscle cell
Correct Answer: To bind to receptors on the muscle fiber and trigger sodium channels to open
Rationale: Acetylcholine is released from the motor nerve ending and binds to receptors on the muscle
cell membrane. This binding triggers the opening of sodium channels, allowing sodium to flow into the
sarcoplasm and initiate the depolarization that leads to contraction.
8. Which of the following correctly describes the difference between a tendon and a ligament?
A) Tendons connect bone to bone; ligaments connect muscle to bone
B) Tendons connect muscle to bone; ligaments connect bone to bone
Anatomy & Physiology I with Lab | Portage Learning | Q & A |
2026/2027 Edition (PDF)
1. Which of the following statements about muscle tissue types is TRUE?
A) Skeletal muscle is under involuntary control
B) Cardiac muscle is striated and involuntary
C) Smooth muscle is striated and voluntary
D) Cardiac muscle is non-striated and involuntary
Correct Answer: Cardiac muscle is striated and involuntary
Rationale: Cardiac muscle is striated like skeletal muscle but is under involuntary control, meaning it
contracts without conscious thought. Smooth muscle is non-striated and involuntary, while skeletal
muscle is striated and voluntary.
2. What percentage of our total body weight does skeletal muscle tissue make up?
A) 20%
B) 30%
C) 40%
D) 50%
Correct Answer: 40%
Rationale: Skeletal muscle tissue accounts for approximately 40% of our total body weight. This makes it
the most abundant tissue type in the body, reflecting its crucial role in movement, posture, and heat
production.
3. What is the functional contractile unit of a skeletal muscle fiber?
A) Myofibril
B) Sarcomere
,C) Myosin filament
D) Actin filament
Correct Answer: Sarcomere
Rationale: The sarcomere is the basic functional unit of a skeletal muscle fiber, extending from one Z line
to the next. It contains overlapping thick (myosin) and thin (actin) filaments whose sliding interaction
produces muscle contraction.
4. Which of the following correctly describes the arrangement of filaments within a sarcomere?
A) Thick filaments are composed of actin; thin filaments are composed of myosin
B) Thick filaments are composed of myosin; thin filaments are composed of actin
C) Both thick and thin filaments are composed of myosin
D) Both thick and thin filaments are composed of actin
Correct Answer: Thick filaments are composed of myosin; thin filaments are composed of actin
Rationale: Sarcomeres contain two types of protein filaments: thick filaments made from myosin and
thin filaments made from actin. During contraction, these filaments slide past one another, shortening
the sarcomere.
5. What happens to the Z lines of a sarcomere during muscle contraction?
A) They move farther apart
B) They move closer together toward the M line
C) They remain in the same position
D) They disappear completely
Correct Answer: They move closer together toward the M line
, Rationale: When a muscle contracts, the Z lines move closer together toward the M line as the
sarcomere shortens. This occurs because the actin filaments slide past the myosin filaments, reducing
the distance between adjacent Z lines.
6. Which band of the sarcomere appears light when stained because it contains only thin filaments?
A) A band
B) H zone
C) I band
D) M line
Correct Answer: I band
Rationale: The I band appears light when stained because it contains only thin (actin) filaments. In
contrast, the A band contains both thick and thin filaments and stains darker.
7. What is the role of acetylcholine at the neuromuscular junction?
A) To break down the motor nerve ending
B) To bind to receptors on the muscle fiber and trigger sodium channels to open
C) To directly cause the muscle fiber to contract
D) To prevent calcium from entering the muscle cell
Correct Answer: To bind to receptors on the muscle fiber and trigger sodium channels to open
Rationale: Acetylcholine is released from the motor nerve ending and binds to receptors on the muscle
cell membrane. This binding triggers the opening of sodium channels, allowing sodium to flow into the
sarcoplasm and initiate the depolarization that leads to contraction.
8. Which of the following correctly describes the difference between a tendon and a ligament?
A) Tendons connect bone to bone; ligaments connect muscle to bone
B) Tendons connect muscle to bone; ligaments connect bone to bone
