The Miller-Urey experiment of 1953 was designed to test the hypothesis that lightning supplied the energy needed to turn atmospheric gases into organic molecules such as amino acids. Which of the following describes why the Miller-Urey theory is widely accepted today?

A

The process of synthesizing organic molecules from a mixture of gases has been successfully modeled in the laboratory.

B

Amino acids spontaneously form from molecules in the atmosphere today.

C

Organic molecules are present today in extremely high concentrations.

D

No other alternative hypotheses have been introduced.

Answer: A. The process of synthesizing organic molecules from a mixture of gases has been successfully modeled in the laboratory.

Explanation:

The Miller-Urey experiment or Miller experiment was a chemical experiment that simulated the conditions thought at the time to be present on the early Earth and tested the chemical origin of life under those conditions. The experiment at the time supported Alexander Oparin's and J. B. S. Haldane's hypothesis that putative conditions on the primitive Earth favoured chemical reactions that synthesized more complex organic compounds from simpler inorganic precursors. Considered to be the classic experiment investigating abiogenesis, it was conducted in 1952 by Stanley Miller, with assistance from Harold Urey, at the University of Chicago and later the University of California, San Diego and published the following year.

After Miller's death in 2007, scientists examining sealed vials preserved from the original experiments were able to show that there were actually well over 20 different amino acids produced in Miller's original experiments. That is considerably more than what Miller originally reported, and more than the 20 that naturally occur in life. More recent evidence suggests that Earth's original atmosphere might have had a composition different from the gas used in the Miller experiment, but prebiotic experiments continue to produce racemic mixtures of simple-to-complex compounds under varying conditions.