n order for muscle contraction to occur during exercise calcium must bind to which of the following proteins? troponin. tropomyosin. myosin. actin.

In order for muscle contraction to occur during exercise, calcium must bind to troponin.

Explanation:

During muscle contraction, the interaction between actin and myosin filaments is crucial. However, for this interaction to happen, specific proteins must undergo a conformational change. Troponin is a complex of three proteins that is found on the thin filament of the muscle fiber. When calcium ions are released into the muscle cells (for example, during exercise), they bind to troponin, causing it to change shape. This change in shape moves tropomyosin — a protein that normally blocks the binding sites on actin — away from these sites, exposing them for binding with myosin. This exposure allows myosin heads to attach to actin, leading to muscle contraction.

Therefore, the correct answer to your question is troponin.