Answer: Myosin.
- A Actin
- B Troponin
- C Tropomyosin
- D Myosin
Correct answer: D. Myosin
Explanation: Myosin forms the thick filaments of the sarcomere. Myosin heads (cross-bridges) bind to actin and pull the thin filaments inward during contraction, shortening the sarcomere.
A sarcomere (Z line to Z line): during contraction the I band and H zone shorten as thin filaments slide over thick, while the A band stays the same length. Image: SlothMcCarty, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.