6 I think but I might be wrong
This is extremely vague, but assuming this is regarding concentration gradient in the nervous system, the Sodium-Potassium pump is responsible for transporting sodium and potassium.
The sentence that states that " When Donnie is unhappy with how an experiment has turned out, he chooses not to share his findings with the public or his colleagues"
"he continues performing an experiment until he reaches the conclusion that he wants and expects. "