Outline how the ATP-PCr system provides energy for immediate muscle contraction. (3 marks)
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Sample Answer
- Muscle contraction begins when stored ATP splits into ADP and inorganic phosphate, releasing immediate energy for movement.
- Phosphocreatine (PCr) rapidly breaks down, donating its phosphate group to ADP, regenerating ATP within milliseconds.
- This phosphate transfer continues without oxygen requirement, sustaining maximal effort for 10-15 seconds until PCr depletes.
- The system’s speed results from PCr stores being located directly in muscle cells, eliminating transport time and enabling explosive movements.
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Sample Answer
- Muscle contraction begins when stored ATP splits into ADP and inorganic phosphate, releasing immediate energy for movement.
- Phosphocreatine (PCr) rapidly breaks down, donating its phosphate group to ADP, regenerating ATP within milliseconds.
- This phosphate transfer continues without oxygen requirement, sustaining maximal effort for 10-15 seconds until PCr depletes.
- The system’s speed results from PCr stores being located directly in muscle cells, eliminating transport time and enabling explosive movements.