Final answer:
A Biochemist or Molecular Biologist conducts experiments on how pH affects enzyme function in digestion, as enzyme activity is sensitive to pH levels.
Step-by-step explanation:
An investigator who conducts an experiment to determine how changes in pH affect the function of enzymes on digestion is most likely to be a Biochemist or a Molecular Biologist. These scientists study the chemical processes and substances that occur within living organisms, and enzymes are key biomolecules in those processes. The activity of enzymes is highly dependent on pH levels since they are proteins that can be affected by the hydrogen ion concentration or pH. Some digestive enzymes, like pepsin in the stomach, require an acidic pH to function optimally, while others, like trypsin in the small intestine, work best in a neutral or slightly alkaline environment. Conducting experiments to evaluate the optimal pH for enzyme activity is a core aspect of research in molecular biology and biochemistry.