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Chapter 12:History of Life on Earth

STUDY
PLAY
Radiometric dating
The estimation of the age of an object by measuring its content of certain radioactive isotopes
Radioisotopes
Charged particles (radiation)
Half-Life
The time required for half of a sample of radioactive substance to disintegrate by radioactive decay or by natural processes
Microspheres
Short chains of amino acids can gather into tiny water droplets
Fossil
The preserved or mineralized remains (bone, tooth, or shell) or imprint of an organism that lived long ago
Cyanobacteria
Photosynthetic prokaryotes
Eubacteria
Prokaryotes that contain a chemical called peptidoglycan in their cell walls
Archaebacteria
Prokaryotes that lack peptidoglycan in their cell walls and have unique lipids in their cell membranes
Endosymbiosis
The theory that mitochondria are descendants of symbiotic, aerobic (oxygen-requiring) eubacteria and chloroplasts are descendents of symbiotic, photosynthetic eubacteria
Protists
Make up a large, varied group that includes both multicellular and unicellular organisms
Extinction
The death of all members of a species
Mass extinction
And episode during which large numbers of species become extinct
Mycorrhizae
Symbiotic associations between fungi and the roots of plants
Arthropod
A kind of animal with a hard outer skeleton, a segmented body, and paired, jointed limbs
Continental drift
The movement of Earth's land masses over Earth's surface through geologic time