BIOL251 Human Anatomy & Physiology I w/Lab 2026 | Module 5 Exam Review |90+ Questions and Answers Summary |LockDown Browser |Portage Learning

BIOL251 Human Anatomy & Physiology I w/Lab 2026 | Module 5
Exam Review |90+ Questions and Answers Summary |LockDown
Browser |Portage Learning



1. A person is lifting a heavy box. Which protein is responsible for performing the
"power stroke" by pulling on the actin filaments?
 A) Troponin

 B) Myosin

 C) Tropomyosin

 D) Titin

Explanation: Myosin is the "thick filament" with heads that bind to actin. When ATP is
hydrolyzed, the myosin head pivots, performing the power stroke that slides the
filaments toward the M-line.
2. Which structure in the muscle fiber stores and releases Calcium ions (


)?
 A) Sarcolemma

 B) Sarcoplasmic Reticulum

 C) T-tubule

 D) Mitochondria

Explanation: The Sarcoplasmic Reticulum (SR) is a specialized endoplasmic reticulum.
Its primary job is to sequester calcium and release it into the sarcoplasm when triggered
by an action potential.
3. What is the role of Acetylcholinesterase (AChE) in the neuromuscular junction?
 A) To stimulate more muscle contractions.

 B) To break down Acetylcholine and stop the contraction.

 C) To release calcium into the synapse.

, D) To bind to the sarcolemma receptors.

Explanation: Without AChE, the muscle would stay in a state of constant contraction
(tetany). AChE breaks down ACh so the muscle can relax and prepare for the next
signal.


4. If a patient is unable to "pucker" their lips to whistle, which muscle is likely
impaired?
 A) Zygomaticus major

 B) Orbicularis oris

 C) Buccinator

 D) Platysma

Explanation: The Orbicularis oris is the circular muscle surrounding the mouth; it is
often called the "kissing" or "whistling" muscle.
5. Which muscle is the primary mover for forced expiration (like coughing)?
 A) Diaphragm

 B) External intercostals

 C) Internal intercostals

 D) Scalenes

Explanation: While the diaphragm is the main muscle for inspiration, the internal
intercostals and abdominal muscles are used during forced expiration to depress the
ribcage.


6. Which muscle of the Rotator Cuff is responsible for the first 15° of arm
abduction?
 A) Infraspinatus

 B) Teres minor

 C) Supraspinatus

 D) Subscapularis

, Explanation: The Supraspinatus initiates abduction. After the first 15°, the Deltoid takes
over as the primary abductor.
7. Which muscle is part of the Quadriceps group and crosses two joints (hip and
knee)?
 A) Vastus lateralis

 B) Rectus femoris

 C) Vastus medialis

 D) Biceps femoris

Explanation: Unlike the three Vastus muscles which only cross the knee, the Rectus
femoris originates on the iliac spine, allowing it to flex the hip and extend the knee
8. During a muscle contraction, which protein myofilament is actively pulled
along?
 (a) Myosin

 (b) Actin

 (c) Troponin

 (d) Tropomyosin

Explanation: According to the Sliding Filament Theory, the thick myosin filaments stay
stationary while their "heads" grab and pull the thin actin filaments toward the center of
the sarcomere (M-line), causing the muscle to shorten.


9. What is the name of the "thick" myofilament found within a sarcomere?
 (a) Actin

 (b) Myosin

 (c) Titin

 (d) Sarcolemma

Explanation: Muscle fibers contain two primary types of myofilaments. Myosin is the
thick filament characterized by "heads" that form cross-bridges, while actin is the thin
filament.
10. To stop a muscle contraction, what must happen to the Calcium ions (