We went to test how long it would take for the test tube to turn yellow and how much of the yellow liquid would deplete over the 48 hour time span. We filled the test tube with Bromothymol Blue Solution, allowing for the runner to blow into the liquid through a straw. After we completed the exercise part of the experiment, small plants were placed inside the test tubes and the test tubes were sealed away in a dark area. The objective was to see how exercise affects the disposal of carbon dioxide from cellular respiration and how light affects the absorption of carbon dioxide. According to the results, the longest time recorded was when the runner ran for a second time, while the shortest time was when the runner ran for the first time. For