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Worksheets22. Sliding Filament Theory
Total questions: 20
Worksheet time: 11mins
Which ion is essential for initiating the sliding filament mechanism in muscle contraction?
Sodium ions
Calcium ions
Potassium ions
Chloride ions
What is the basic contractile unit of a myofibril in skeletal muscle?
Sarcomere
Myosin
Actin
H zone
Which protein forms the thick filaments in the sliding filament theory?
Actin
Myosin
Troponin
Tropomyosin
What structure marks the boundary between adjacent sarcomeres?
H zone
I band
A band
Z line
Which band of the sarcomere contains only thin filaments and appears lighter under a microscope?
A band
I band
H zone
Z line
What is the function of ATPase in muscle contraction?
Stores calcium ions
Forms cross-bridges
Breaks down ATP to release energy
Binds to actin
Which protein blocks the myosin-binding sites on actin when the muscle is at rest?
Troponin
ATPase
Myosin
Tropomyosin
What is the role of troponin in muscle contraction?
Binds to ATP
Binds to calcium ions and moves tropomyosin
Forms the thick filament
Stores energy
Where are sarcomeres located?
Muscle fibre
Fascicle
Perimysium
Myofibril
What forms the cross-bridges during muscle contraction?
Actin heads attaching to myosin
Myosin heads attaching to actin
Troponin binding to tropomyosin
ATP binding to calcium
What is the main energy source for muscle contraction?
Glucose
ATP
Calcium ions
Oxygen
Which structure is composed of repeating units of sarcomeres?
Myofibril
Z line
H zone
Troponin
What happens to the Z lines during muscle contraction?
Move further apart
Close up completely
Remains the same
Move closer together
Which molecule blocks the active site on actin when muscles are relaxed?
Tropomyosin
Calcium
Troponin
ATP
What is the function of calcium ions in the sliding filament theory?
Provide energy for contraction
Bind to troponin to expose binding sites on actin
Form cross-bridges
Block myosin heads
Which protein filament is described as the 'thin filament' in muscle fibres?
Myosin
Troponin
Actin
ATPase
What is the role of ATP in the detachment of myosin heads from actin?
It causes the myosin head to attach to actin
It provides energy for the myosin head to detach from actin
It blocks the binding site
It stores calcium ions
Which of the following best describes the sliding filament theory?
Actin and myosin filaments shorten during contraction
Only myosin filaments move during contraction
Only actin filaments move during contraction
Actin and myosin filaments slide past each other, shortening the sarcomere
What is the correct sequence of events in muscle contraction according to the sliding filament theory?
ATP binds to myosin → Myosin attaches to actin → Calcium released → Cross-bridge forms
Calcium released → Binds to troponin → Tropomyosin moves → Myosin binds to actin
Myosin binds to actin → Calcium released → ATP binds to myosin → Cross-bridge forms
Tropomyosin moves → Calcium released → Myosin binds to actin → ATP binds to myosin
Actin are the (a) and myosin are the (b) filaments.
