Practice IB Sports, exercise and health science (SEHS) Topic B.1.3 Muscular Function with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for B.1.3 Muscular Function and mirrors Paper 1A, 1B, 2 style where relevant.
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Cardiac troponin (cTn) is a key protein involved in the regulation of muscular contraction in cardiac muscle, through interaction with actin, tropomyosin, and calcium ions during the sliding filament mechanism. This study evaluated the effect of endurance exercise (marathon running) on cTn release in 151 athletes using serological data. Figure A shows the time course of exercise-induced cTn concentration changes. Figure B displays individual post-marathon cTnI levels relative to the upper reference limit (URL) for normal.
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.056208
Refer to Figure A. At what time interval is peak cTn concentration observed post-exercise?
Refer to Figure B. Calculate the percentage of individuals who had post-marathon cTn concentrations above the normal URL.
Cardiac troponin is part of the regulatory system in cardiac muscle contraction. Identify the role of troponin in the sliding filament mechanism.
Given that cTn concentrations return to normal within 72 hours, evaluate whether this pattern supports a physiological rather than pathological role for cTn release in endurance athletes.
The table below shows the primary joint actions of three muscles in the human body.
| Muscle | Primary Joint Action |
|---|---|
| Pectoralis major | Shoulder adduction |
| Triceps brachii | Elbow extension |
| X | Dorsiflexion |
Which muscle is represented by X in the table?
Which molecular event is necessary for the increased actin–myosin overlap shown from the first diagram to the third diagram?
Why are isometric contractions useful during early-stage rehabilitation when joint movement is limited?
Which event occurs immediately after ATP binds to myosin during the cross-bridge cycle (next mechanical event)?