Experiments often involve two main variables: the independent variable and the dependent variable. In an experiment, the dependent variable is always the main factor being studied; also, this is "dependent" because it is affected by other factors. In the case presented, the dependent variable is seed growth because this is the specific phenomenon that is being analyzed. Moreover, this factor is affected by the changes in pH. On the other hand, the pH, which is the second factor is the independent variable because this is not affected by the first variable and it is manipulated on purpose.
