The ability of a muscle to contract and relax is dependent on the flow of what substance out of and into its storage site in the muscle cell?

The correct answer will be- Calcium

Explanation:

Muscle contraction and relaxation are dependent on the presence or absence of an element which controls the movement of troponin and tropomyosin in the muscles that are calcium.

Calcium help forms the cross-bridge as the troponin gets activated in the presence of calcium which causes conformational changes in the troponin which allows the movement of the tropomyosin from the myosin-binding sites. The movement of troponin-tropomyosin helps the formation of cross-bridge which allows muscle contraction and relaxation.

Thus, calcium is the correct answer.

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