1. Water Cycle (7 points) a. How was the water cycle demonstrated in the terrarium after the plants sprouted? (3 points)

b. Draw a diagram of the water cycle in a terrarium, including labels. (4 points)

2. Carbon Dioxide and Oxygen Cycles with Plants Only (7 points)
a. How did CO2 and O2 cycle in the terrarium when it contained only plants? (3 points)

b. Add arrows and labels to the diagram you drew for Step 1b to show how CO2 and O2 cycle in the terrarium. (4 points)

3. Carbon Dioxide and Oxygen Cycles with Plants and Animals (7 points)
a. How did adding animals change the cycles of CO2 and O2 in the terrarium? (3 points)

b. Add more arrows and labels to the diagram you drew for Step 1b to show how CO2 and O2 move when animals are also in the terrarium. (4 points)

4. Why did you have to start with live plants or wait until the seeds sprouted before adding the animals? Describe your answer in terms of how the CO2 and O2 might be out of balance in your terrarium. (3 points)

5. Did the amount of water that condensed at the top of the terrarium change as the plants sprouted and grew? Describe what you observed, using data from your experiment. Why do you think this happened? (3 points)

6. Think about whether it's easy or difficult to maintain life in a terrarium. (3 points)
a. Imagine having to design a terrarium that would include every living thing on Earth. Describe how easy or difficult you think this would be and why. (1 point)

b. Biosphere 2 is a large terrarium built near Tucson, Arizona. It takes up the space of several buildings, and it houses hundreds of species. Some people have suggested that we build a giant terrarium that people could live in on the Moon or Mars. Do you think building a giant, self-sustaining place somewhere else would be realistic? Why or why not? (1 point)

c. Terri Swearingen, an environmental activist, once said, "We are living on this planet as if we had another one to go to." What do you think about this quote? (1 point)