splehem

Okay, so heres the deal. I have a paper due tomorrow about how i plan on making an ecosystem in a bottle, and what im going to test. But i have NO idea where to start. Mostly i need an idea for an experiment. It has to test how ecosystems work etc..not just the plants in it. What should i test? i was thinking maybe seeing if plants grow better on their own or with other types of plants inside of the bottle, is this a good idea? any ideas?