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The estimation of the age of an object by measuring its content of certain radioactive isotopes
The time required for half of a sample of radioactive substance to disintegrate by radioactive decay or by natural processes
The preserved or mineralized remains (bone, tooth, or shell) or imprint of an organism that lived long ago
Prokaryotes that lack peptidoglycan in their cell walls and have unique lipids in their cell membranes
The theory that mitochondria are descendants of symbiotic, aerobic (oxygen-requiring) eubacteria and chloroplasts are descendents of symbiotic, photosynthetic eubacteria
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