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Muscle and Motility · Paper 1 — Free Biology HL Practice Questions

What this topic covers

This theme is built on one repeated argument: structure exists because it does a job, and you can predict the job from the structure. Examiners test this exact logic at every scale — a motor protein's shape tells you which way it walks a microtubule, a red blood cell's missing nucleus tells you why it can pack more haemoglobin, a gill's countercurrent geometry tells you why it out-performs a lung-style parallel flow. Several chunks here — muscle and motility, enzyme kinetics, endosymbiotic theory, detailed phloem loading — exist only on the HL paper, and they're flagged below. Get the mechanism words right (troponin, not tropomyosin; ATP-binding, not hydrolysis) because that's where the marks actually sit.

Read the full Form and Function lesson notes →

1FoundationMCQMuscle structure and contraction mechanisms1 markPaper 1~2 min

A student examines a stained cross-section of human tissue under a light microscope. The cells are elongated and multinucleate, with nuclei positioned at the cell periphery. Striations are clearly visible, and the tissue is under voluntary control. Which additional microscopic feature would most specifically distinguish this tissue from all other muscle types?

Solutions

2MasteryMCQMuscle structure and contraction mechanisms1 markPaper 1~2 min

A researcher blocks ATP binding to myosin heads in a single sarcomere undergoing isometric contraction at a sarcomere length of

2.2\ \mu\text{m}

. Which of the following best describes the immediate effect on the cross-bridge cycle?

Solutions

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