Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[Q]: Question: The voltage of a voltaic cell can be determined by the reduction potentials of what? Answer: half reactions
[A]: The voltage of a voltaic cell can be determined by the reduction potentials of the half reactions.

[Q]: Question: Why are noninfectious diseases not contagious? Answer: non-pathogen caused
[A]: Noninfectious diseases are not contagious because they are not caused by pathogens. Instead, they are caused by such factors as lifestyle choices, environmental toxins, or mutations.

[Q]: Question: Where does the process of digestion start? Answer: mouth
[A]:
Digestion starts in the mouth. When food is swallowed, it travels through the esophagus to the stomach. In the stomach, digestion continues and a small amount of absorption of nutrients takes place.