IB SEHS B.1.3 Muscular Function

What is the first step in the sliding filament theory of muscle contraction?

• Relaxation of the muscle fibers

• Contraction of the myosin heads

• Release of calcium ions from the sarcoplasmic reticulum

• Binding of troponin to tropomyosin

Which protein binds to calcium ions during muscle contraction?

• Troponin

• Myosin

• Calmodulin

• Actin

What happens to the myosin heads during the power stroke?

• The myosin heads detach from actin filaments.

• The myosin heads move away from the center of the sarcomere.

• The myosin heads pivot towards the center of the sarcomere.

• The myosin heads remain stationary.

What is the role of ATP in muscle contraction according to the sliding filament theory?

• ATP is only needed for muscle stretching, not contraction.

• ATP causes muscle relaxation instead of contraction.

• ATP is produced by actin filaments during muscle contraction.

• ATP provides energy for myosin heads to bind, detach, and reset during muscle contraction.

During muscle relaxation, what happens to the actin and myosin filaments?

• They contract and bind tightly together.

• They remain stationary and do not move.

• They disintegrate and break apart.

• They slide apart and detach from each other.

What is the function of tropomyosin in muscle contraction?

• Initiates muscle contraction

• Stabilizes the sarcomere

• Regulates the interaction between actin and myosin

• Promotes the release of calcium ions

What is the final step in the sliding filament theory of muscle contraction?

• Binding of myosin heads to actin filaments

• Detachment of myosin heads from actin filaments

• Relaxation of the muscle fibers

• Release of calcium ions from the sarcoplasmic reticulum

What is the basic mechanism involved in muscle contraction?

• Muscles push on the bones

• Muscles pull on the bones

• Muscles remain the same length

• Muscles contract and relax

What causes the filaments to slide in muscle contraction?

• Release of calcium ions

• Presence of troponin and tropomyosin

• Interaction of myosin and actin molecules

• Detachment of myosin from actin molecule

What is the energy source for muscle relaxation?

• Adenosine Triphosphate (ATP)

• Calcium ions

• Myosin crossbridges

• Troponin and tropomyosin