Answer the following four questions. Responses must be justified using material from the lecture, text, and/or other references. Each response should be about half a page or 5-8 sentences.

1) What is the definition of an organic compound? Why are Si, P, and S considered to be possible elements that could also support life? What type of environment might be more suitable in this situation?

2) What was the purpose of the solar eclipse experiment? How many observations are needed to conduct this experiment? What conclusions were drawn from the results?

3) What does it mean to say that the universe is homogeneous and isotropic? Why are these assumptions important in the field of astronomy?

4) Briefly describe the process of UV photolysis. Why is it important to the search for life elsewhere in the universe? What problem does it help solve?