Question

which two myofilaments (protein molecules) must engage to create a muscle contraction?
○ fascicle & actin
○ actin & perimysium
○ troponin & tropomyosin
○ actin & myosin

Explanation:

To determine the correct myofilaments for muscle contraction, we analyze each option:

• "fascicle & actin": A fascicle is a bundle of muscle fibers, not a myofilament, so this is incorrect.
• "actin & perimysium": Perimysium is connective tissue around fascicles, not a myofilament, so this is incorrect.
• "troponin & tropomyosin": These are regulatory proteins associated with actin, not the main contractile myofilaments that engage to cause contraction.
• "actin & myosin": Actin (thin myofilament) and myosin (thick myofilament) interact (cross - bridge formation) to produce muscle contraction.

Answer:

D. actin & myosin