What you are seeing in this homemade biosphere is photosynthesis and cellular respiration in action. When sunlight strikes the plants, bubbles of oxygen stream off the leaves into the water giving life sustaining oxygen to the shrimp and snail in this sealed system. Elodea is used in college level experiments to demonstrate this phenomena that can be seen in this biosphere. We have all heard that plants give off oxygen, but seeing is believing. It is light that provide energy for the life in this jar and also our planet. The famous equation that goes with this is… 6H2O + 6CO2 + Light energy → C6H12O6 + 6O2 or water plus carbon dioxide plus light produces cellulose and oxygen