The problem of this experiment is--at which pH does this enzyme work most effectively? Hypotheses to be tested include: this enzyme works best at an acidic pH, or, this enzyme works best at an alkaline pH, or, this enzyme works best at a neutral pH. The way to find out is to allow it to react at various pH values and to collect the amount of product that forms. Enzymes perform best at optimal conditions of pH, temperature and concentration. By analyzing the data collected during this experiment, one could learn at which pH this enzyme works optimally. An example in the human body is gastric protease which is an enzyme that performs best in an acidic pH. The stomach contains hydrochloric acid which provides the environment for the protease to perform its job--hydrolyze protein. In the experiment described by your data, the independent variable is the pH values that are varied during the experiment and the dependent variable is the amount of product produced.