A Guide to the GRE/Buried Conclusions

The key points of the author are often hidden amidst thick text. Practice identifying them and picking them out.

Though commonly thought of as a theory on the origins of life, biological evolution in fact does not address this topic, but rather, the diversity of life. The concept of 5 the origins of life is called “abiogenesis” and was the question addressed by the famous Miller and Urey experiment. In 1952, the two namesakes of this experiment built a machine which applied 10 heat and electrical sparks to water and a plethora of gases to determine whether amino acids, a fundamental component of life on Earth, could form from these chemicals. The experiment produced over 15 twenty amino acids, but, while frequently cited as a milestone in the research of abiogenesis, the experiment is just as heavily disapproved by many for its inaccuracies. These criticisms are 20 heavily misplaced. Critics frequently point out that the gases used in the Miller and Urey experiment were probably quite different from those which made up the Earth's atmosphere 25 billions of years ago, and therefore, the experiment is inaccurate and its informative nature is limited. The point of the experiment, however, was never to attempt to simulate actual abiogenesis. 30 Miller and Urey were concerned with the question of whether or not amino acids could arise from gases, water, heat, and electricity, and in their research, they proved just what they set out to 35 determined. 1. What was the “Miller and Urey” experiment and what did it seek to accomplish?

2. How did the Miller and Urey experiment proceed? What was done in the experiment?

2. According to the passage, what is a common criticism of the Miller and Urey experiment, and how does the author feel with regard to this criticism?

3.06 Buried Conclusions

Answers to Practice Questions

1. The Miller and Urey experiment sought to see whether amino acids - a basic component of life - could be produced from naturally occurring gases through application of heat and electricity. The experiment was a success, and produced over twenty such amino acids.

2. The Miller and Urey experiment ran a group of different gases (“plethora”) through a machine which applied heat and electrical sparks to these gases as well as water.

2. The passage explains that the Miller and Urey experiment is commonly criticized because the gases used in it were probably quite different from the early atmosphere on Earth. However, the author claims that this is not a valid criticism. As the author explains, the purpose of the experiment wasn't to simulate how life arose on Earth. Rather, the purpose was to determine whether it was possible for amino acids to form naturally under certain circumstances. The experiment showed this, and thus was a success.