Practice IB Biology Topic B3.3 Muscle and Motility with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for B3.3 Muscle and Motility and mirrors Paper 1A, 1B, 2 style where relevant.
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| Sarcomere Region | Resting Length (μm) | Contracted Length (μm) |
|---|---|---|
| A-band | 1.8 | 1.8 |
| I-band | 0.7 | 0.4 |
| H-zone | 0.4 | 0.1 |
Based on the data, which conclusion best supports the sliding filament mechanism?
Which change would be observed in the diagram if the forearm were flexed instead of extended?
What is the role of calcium ions released from the sarcoplasmic reticulum?
The table shows events occurring during the contraction of a skeletal muscle fibre.
| Process | Immediate cause | |
|---|---|---|
| I | Power stroke | ATP binding to the myosin head |
| II | Myosin detachment | Tropomyosin moving to cover the actin filament |
| III | Exposure of binding sites | Calcium ions binding to troponin |
| IV | Myosin head re-cocking | Release of ADP and inorganic phosphate |
Which row correctly matches a process with its immediate cause?
The diagram below shows the structure of a sarcomere in a relaxed muscle fibre.
During muscle contraction, which of the labelled regions maintains a constant width?