Answer:
The correct answer will be-
A) Myosin head forms a cross-bridge with actin
B) Myosin pulls actin toward center of sarcomere
C) Myosin binds ATP
D) Myosin hydrolyzes ATP to ADP and Pi
E) Cross-bridge between myosin and actin is broken
F) Myosin releases Pi
G) Myosin head extends.
Explanation:
The sarcomere is the structural and functional unit of the muscle which when contracts and relaxes causes the muscle movement.
The sarcomere is composed of actin and myosin filaments which respond in the presence and absence of calcium ions.
When the calcium ions are present, the myosin head binds the actin. The binding of myosin to actin pulls the thin filament shortening the sarcomere and contraction of the muscle.
The myosin head then attaches the ATP molecule which leads to the detachment of the myosin from the actin. This is followed by the breakdown of the ATP into ADP and Pi by ATPase activity. This allows the myosin head to extend and ready to bind actin again and the cycle continues.