Scientists think that earth formed more than 4 billion years ago by the gravitational accumulation of dust and debris moving through space
Isotopes are atoms with varying numbers of neutrons
The ages of rocks and other materials cam be determined by measuring the amount of radioactive decay that has occurred in radioactive isotopes found in samples of those materials
an isotope's half-life is the time that one-half of a sample of the isotope takes to decay.
The first simple organic compounds on early Earth may have formed under conditions of heat energy and in an atmosphere very different from that of today's Earth
Meteorites may have brought organic compounds to earth.
Three Major scientific inferences about the first living things on earth
- Scientists think that little or no oxygen gas existed on early earth
- oldest fossils are thought to be the same size and shape of prokaryotes
- First cells might have developed in an environment filled w/ organic molecules for food
Further chemical reactions may have converted simple organic compounds into the complex macromolecules important to life
cell- like structures, including microspheres and coacervates, form spontaneous in certain kinds of solutions.
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