AIIMS 2017 Zoology Sliding Filament Theory MCQ Question

In the sliding filament theory, muscle contraction continues as long as ATP binds to the myosin head, allowing it to detach from actin and re-cock for another power stroke. When ATP binds, it hydrolyzes to ADP and inorganic phosphate (Pi), which are necessary for the myosin head to reset and continue the contraction cycle. Option B is incorrect because ADP binding alone does not sustain contraction; ATP is essential for detachment. Options C and D are also incorrect as the presence of calcium ions in the sarcoplasm (C) initiates contraction, but ATP is required for its continuation, while polymerization of the myosin head (D) is not a relevant factor in the contraction process.