Will has an aquarium with water, plants, and fish that eat the plants. It is sealed so no material can get in or out, and has glass sides that allow sunlight to come
in. The aquarium can also be covered to prevent light from entering.
The amount of carbon in the aquarium's water started out high. Now, the amount
of carbon in the water is decreasing.
Is the aquarium now in sunlight or is it covered? What is happening to the number
of energy storage molecules in the plants and fish as a result?