Question

Which statement accurately states what happens when a muscle contracts?

A) Calcium combines with ATP to produce sarcomeres
B) Myosin head attach to and pull on a series of actin-binding sites
C) Actin produces myosin and ATP
D) Calcium produces contractions

Answer 1

B) myosin head attach to and pull on a series of actin-binding sites

Answer 2

B) Myosin head attach to and pull on a series of actin-binding sites

Step-by-step explanation:

Myosin head have ADP and Pi bound to it and binds to active site on actin filament to form a cross bridge. This is followed by release of inorganic phosphate from myosin head to trigger the power stroke during which myosin head pulls the actin filament towards the center of sarcomere. ADP is also released from the myosin head during power stroke. Binding to ATP to the myosin head restore its energized state to begin the cycle again. During each power stroke, movement of actin filament towards the center of sarcomere shorten the muscle.