The setup shows four test tubes. Tube 1 contains water only. Tube 2 contains a live snail. Tube 3 contains a live green water plant. Tube 4 contains both a live green water plant and a live snail. We know that plants can photosynthesize. We also know the product of photosynthesis is the reactant of cellular respiration. In this setup, which tubes contains an organism(s) carrying on cellular respiration?