Muscle contraction Quiz
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5 questions, one answer each
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1. What happens to the H zone during contraction?
- A. It gets wider
- B. It stays the same
- C. It gets narrower
- D. It becomes the A band
2. Which protein binds calcium ions to start contraction?
- A. Actin
- B. Troponin
- C. Myosin
- D. Tropomyosin
3. What is the immediate result of ATP binding to a myosin head?
- A. The head binds to actin
- B. The power stroke occurs
- C. Calcium is released
- D. The head detaches from actin
4. What would happen to a muscle fibre if calcium release was blocked?
- A. Contraction would be stronger
- B. Tropomyosin would continue to block the binding sites, so no contraction
- C. Cross-bridges would form but not detach
- D. The A band would shorten
5. In rigor mortis the muscle is stiff because:
- A. Myosin heads cannot detach from actin
- B. Too much ATP is present
- C. Tropomyosin covers the binding sites
- D. Actin filaments have shortened