Myosin not only binds to actin, but is also an enzyme that hydrolyzes ATP to ADP. Which of the following is false? An action potential in the muscle cell activates contraction by releasing Ca2+ within the muscle. A single action potential at the neuromuscular junction is sufficient to cause a muscle to twitch. Summation of twitches is an "all-or-none" phenomenon that occurs in a single muscle fiber. The tension generated by a muscle can be varied by controlling how many of its motor units are active.

Summation of twitches is an "all-or-none" phenomenon that occurs in a single muscle fiber

Explanation:

The all-or-none principle states that the strength at which the nerve or muscle fiber responds to a stimulus is not dependent on the strength of the stimulus.

In a summation of twitches, the tension of the muscle increases with each twitch. Therefore as the action potential increases its firing, the muscle contraction increases, thus increasing muscle tension.

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

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3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.