Question

1. muscle contractions will continue to occur as long as there is or available.

Explanation:

Muscle contractions rely on two key elements. Calcium ions (\(Ca^{2+}\)) play a crucial role in the process of muscle contraction by binding to troponin, which causes a conformational change that exposes the myosin - binding sites on actin. Adenosine triphosphate (ATP) is the energy currency of the cell. It provides the energy required for the myosin head to detach from actin (during the cross - bridge cycle) and for the re - uptake of calcium ions back into the sarcoplasmic reticulum. As long as these two (calcium ions and ATP) are available, the cycle of muscle contraction (attachment of myosin to actin, power stroke, detachment of myosin from actin, and re - cocking of the myosin head) can continue.

Answer:

Calcium ions (\(Ca^{2+}\)), Adenosine triphosphate (ATP)