I put snails and Elodea plants into test tube bottles that contains Bromothymol Blue. The left four were put under dark light and the right four were put under bright light. Explain what each of the test tubes went through (photosynthesis, cellular respiration, both, or neither) Test tube 2 has a snail. Test tube 3 has a elodea plant. And test tube number 4 has both of them. All of them were a green color (medium level of carbon dioxide) at the beginning.