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Muscle contraction Knowledge-Based Practice

Biology · Human Body & Physiology · Biology · Support & Movement

5 Biology practice questions on Muscle contraction. Questions that assess core concepts and understanding.

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Questions

  1. 1.

    Which of the following processes is directly required for a skeletal muscle fiber to relax following contraction?

    • A) Passive diffusion of calcium ions out of the sarcoplasm through open ryanodine channels
    • B) Enzymatic degradation of troponin and tropomyosin complexes by sarcoplasmic proteases
    • C) Active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum
    • D) Influx of sodium ions across the sarcolemma via voltage-gated sodium channels
  2. 2.

    What is the primary function of transverse tubules (T-tubules) during excitation-contraction coupling in skeletal muscle fibers?

    • A) Storing and releasing the calcium ions that interact with the contractile apparatus
    • B) Rapidly propagating electrical action potentials deep into the interior of the muscle fiber
    • C) Hydrolyzing ATP to energize the cocking mechanism of the myosin globular heads
    • D) Directly pulling thin actin filaments toward the center of the sarcomere during shortening
  3. 3.

    According to the sliding filament theory, which of the following structural changes occurs within a sarcomere during skeletal muscle contraction?

    • A) The length of the A band decreases significantly.
    • B) The width of the H zone decreases as thin filaments slide toward the M line.
    • C) The distance between consecutive Z discs increases.
    • D) The thick filaments physically shorten along their longitudinal axis.
  4. 4.

    During the cross-bridge cycle of skeletal muscle contraction, which event directly causes the myosin head to detach from actin?

    • A) Binding of a new ATP molecule to the myosin head
    • B) Hydrolysis of ATP into ADP and inorganic phosphate
    • C) Release of inorganic phosphate from the myosin head
    • D) Active transport of calcium ions back into the sarcoplasmic reticulum
  5. 5.

    During the contraction of a skeletal muscle fiber, which of the following events occurs as a direct result of calcium ions binding to troponin?

    • A) ATP binds to the myosin head, causing it to detach from the actin filament.
    • B) Tropomyosin shifts away, exposing the myosin-binding sites on the actin filament.
    • C) The sarcoplasmic reticulum actively pumps calcium ions back into its lumen.
    • D) Acetylcholine diffuses across the synaptic cleft to bind to receptors on the sarcolemma.

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