- A It serves as the single primary fuel source that sustains prolonged, long-duration aerobic endurance exercise lasting many hours overall in most cases under typical conditions
- B It is a rapid phosphate buffer; donates phosphate to ADP to regenerate ATP immediately at start of intense exercise, before other metabolic pathways activate
- C It serves as the main intracellular calcium storage reservoir located mainly within the muscle sarcoplasm near the SR according to standard textbooks in general practice
- D It directly and physically forms the actual actin-myosin cross-bridge structure itself during each cycle of muscle contraction as frequently described in most textbook accounts
Correct answer: B. It is a rapid phosphate buffer; donates phosphate to ADP to regenerate ATP immediately at start of intense exercise, before other metabolic pathways activate
Explanation: Creatine phosphate (phosphocreatine) provides the fastest ATP regeneration: CP + ADP → C + ATP (creatine kinase). This buffer lasts only 10-15 seconds of maximal effort. After this, glycolysis and then oxidative phosphorylation become the primary ATP sources.
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.