The early atmosphere on Earth is thought to have lacked which of the following gases?

Measurements indicate that a fossilized skull you unearthed has a carbon-14: carbon-12 ratio about 1/16th that of the skulls of present-day animals. What is the approximate age of the fossil? (The half-life of carbon-14 is 5,730 years.)

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora?The researchers know that correlation does not equal causation. However, can the absence of a correlation enable you to reject a hypothesis of causation? How would the R2 values be different in a scenario where a single trait was important to diversification in many phyla versus a scenario where different traits were important to diversification in different phyla?

SCIENTIFIC THINKING When Stanley Miller's experiment was published in 1953, his results made global headlines. The general public thought Miller had answered the question of how life on Earth began by creating life in a test tube. However, scientists understood that Miller's experiment was neither a final answer nor a recipe for life. Rather, it was the first test of a long-standing hypothesis about the origin of life. Write an essay describing how the process of science progresses over time toward understanding how nature works.

Why is the four-stage hypothesis for the abiotic origin of life useful?

Currently scientists think the early atmosphere probably consisted of __________.

The Miller and Urey abiotic synthesis experiment (and subsequent, similar experiments) showed that __________.

The early atmosphere may not have been as reducing as originally postulated by Haldane, Oparin, Miller, and Urey. In light of current thinking about the composition of the early atmosphere, what is regarded as a likely place for the abiotic synthesis of organic molecules to have occurred?

Abiotically produced vesicles display which of the following rudimentary qualities necessary for life?