I think the correct answer is ions.
An action potential occurs when a neuron sends information down an axon, away from the cell body. A neuron that emits an action potential, or nerve impulse is said to fire. These action potentials are generated by special types of voltage hated ion channels that are embedded in the plasma membrane of the cell.
It would show that is universe in not expanding but contracting
A I think but can you get a better picture of the questions
The answer is NAD+.
In the process of glycolysis, NAD+ is reduced to form NADH+ and H+. If NAD+ is not present, glycolysis will not be able to continue. Under anaerobic conditions, the regeneration of NAD is coupled to the reduction of pyruvate. The anaerobic regeneration of NAD is called fermentation.
In animal tissues , fermentation occurs as pyruvate acts as a makeshift hydrogen acceptor and gets reduced to lactate when NADH transfers electrons to pyruvate. This enzyme catalyzed reaction occurs whenever the available oxygen has been consumed.