1. What hypothesis did Miller and Urey test in their famous experiment?
What evidence did scientists use to determine the age of the planet and the composition of the ancient atmosphere?
How would the appearance of protocells have represented a key step in the origin of life?
What proposed energy sources existed on the early (pre-life) Earth?
How do scientists think macromolecules formed on the early (pre-life) Earth?

2. Identify environmental conditions that could result in punctuated equilibrium and conditions that result in gradualism.
State the endosymbiotic theory and provide 4 evidence.
List two processes that could increase the pace of speciation on the planet and explain how each did so.
Explain how oxygen first appeared in the atmosphere and how many living organisms responded to it.

3. Analyze the graph on atmospheric oxygen concentration over time on the planet and give potential explanations of each fluctuation.

5. Explain how sexual selection can result in speciation.
Describe how the appearance of a geographic barrier can result in speciation.
Why did life appear so late on land during the history of life on earth?
List three major evolutionary changes that must have occurred to support life on land.
What is meant by the Cambrian explosion 500 million years ago?

6. Stromatolites