Choose the best answer to fill in the blanks. A scientist designs a study to investigate the relationship between heart rate and physical activity in 25 subjects. The results indicate that heart rate increased significantly following 20 minutes of physical activity. In this experiment, the dependent variable is ______________ and the independent variable is _______________.

MCQs on the physiological processes that occur within the human body, with particular attention on enzyme activity, cell signaling, metabolic processes, protein synthesis, and movement.