The document summarizes theories on the origins of life on Earth including the Miller-Urey experiment, formation of early cells around thermal vents, RNA as the first genetic material, and the endosymbiotic theory. The Miller-Urey experiment showed how organic molecules could form in conditions similar to early Earth. Early cells may have assembled around thermal vents where organic polymers could concentrate. The endosymbiotic theory proposes that mitochondria and chloroplasts in eukaryotic cells originated as prokaryotic endosymbionts that were engulfed by other cells and evidence supports some bacteria living within archaea or eukaryotes.

1. IB Biology: Origins of Cells (1.5) Review NAME:
1. In 1953, Miller and Urey performed a famous experiment that lent weight to the spontaneous generation hypothesis for the
origins of life on Earth:
a. Outline the central idea of the spontaneous generation hypothesis:
b. What aspects ofthe early Earth’s conditions did Miller and Urey include in their model?
c. Describe the Miller-Urey experiment and its findings:
2. Miller and Urey’s work showed how the first organic molecules might have formed, but the origins of the first cells, which
emerged on Earth 3.5-3.6 billion years ago, pose further questions:
a. Why do scientists hypothesize that simple organic molecules assembled into polymers around thermal vents?
b. Describe how the first cell membranes may have formed:
c. Identify at least two reasons that scientists believe RNA is was the most likely genetic material of the first cells:
3. What is explained by the Endosymbiotic Theory?
4. Annotate the diagram, below, to describe the theorized stages of endosymbiosis:
5. State at least four pieces of evidence that support the endosymbiotic theory: