Biology Chapter 19

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Terms in this set (...)

extinct
The death of every member of a species
paleontologist
scientist who specializes in the study of fossils and ancient forms of life
relative dating
any method of determining whether an event or object is older or younger than other events or objects
index fossil
a fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found
radiometric dating
the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products
half-life
The time required for one half of the atoms of a radioisotope to emit radiation an decay products (like an "atomic clock", used to figure out how old something is)
geologic time scale
scale used by paleontologists to represent evolutionary time
era
A unit of geologic time larger than a period. Example: Mesozoic = Age of Middle Life
period
A unit of geologic time smaller than an era. Example Jurassic
plate tectonics
The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle. (Newer version of Continental Drift).
macroevolutionary patterns
grand transformations that usually take place in clades larger than a single species
background extinction
normal, low-level rate of extinction of species b/c of naturally changing environment conditions
mass extinction
event in which many types of living things become extinct at the same time: often catostrophic
gradualism
SLOW AND STEADY EVOLUTION- The theory that evolution occurs slowly but steadily
punctuated equalibrium
STOPS and SPURTS of EVOLUTION- Theory that evolutions occurs with relatively sudden periods of speciation followed by long terms of stability
adaptive radiation
process by which a single species or a small group of species evolves into several different forms that evolve in different ways
convergent evolution
Evolution toward similar characteristics in unrelated species
coevolution
Process by which two species evolve in response to changes in each other
endosymbiotic theory
a theory that states that certain kinds of prokaryotes began living inside of larger cells and evolved into the organelles of modern-day eukaryotes. EX; mitochondria were simple creatures that were "enslaved"/engulfed by larger cells to make ATP
Miller-Urey Experiment
Two scientists attempted to reproduce the condition of the (assumed) earth's primitive ocean's under a reducing atmosphere. They produced some of the key molecules to life (amino acids and nucleotides) but had started with much simpler inorganic ingredients.
Chemical Evolution
The formation of complex organic molecules from simpler inorganic molecules through chemical reactions in the oceans during the early history of the Earth; the first step in the development of life on this planet. The period of chemical evolution lasted less than a billion years.
cyanobacteria
a simple bacterium that can carry out photosynthesis, such as a blue-green alga; though to be one of the first living things
Primordial Earth
Big ball of magma that slowly cooled until it had a solid crust. dense material sank to core & light material floated to surface
Primoridial Soup
A somewhat playful term used to describe the chemical broth on ancient Earth within which life evolved like a volcanic crock pot over hundreds of millions of years. (What the start of the Miller-Urey experiment tried to recreate.)
Age of the Earth
Approximately 4.6 Billion Years Old. 4,600,000,000 years old.

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