A smallest contractile unit of muscle contraction called sarcomere is the area between two:
Correct answer: C. Z- Line
- A. H- zone
- B. M- Line
- C. Z- Line
- D. A band
Explanation
A sarcomere extends from one Z-line to the next Z-line, and these boundaries move closer during contraction. Students may choose the M-line because it lies at the centre of the sarcomere, but it is a central landmark rather than a boundary.
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About Muscle Contraction
Muscle contraction is explained by the sliding filament model, in which myosin heads pull actin filaments within sarcomeres using ATP. The topic covers calcium, troponin, tropomyosin, the neuromuscular junction and relaxation, with attention to how filament length stays almost constant while the sarcomere shortens.
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