Answer:B. Based on the frequency of the action potential.
Explanation:
Answer - D. Prokaryotes are only single-celled.
Reasoning - Reason why they are single-celled are unicellular is because they do not have a bound nucleus membrane.
<span>Animal-like protists are called protozoa. Protozoa are single-celled eukaryotes that share some traits with animals. Like animals, they can move, and they are heterotrophs.
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The correct answer is option B, that is, the release of calcium ions makes actin and myosin to combine with each other.
At the time of the stimulation for a muscle contraction, calcium is discharged into the fiber. It combines with troponin and instigates it to move tropomyosin, exposing the binding site for the myosin cross-bridge. Thus, the face of the actin filament is now free to combine with myosin heads to initiate contraction of the muscle.
