| A | B |
|---|
| colony | collection of autonomously replicating cells of the same species |
| genetic annealing | production of a new genome through the transfer of part of the genome of one organism to another organism |
| geologic record | division of Earth’s history into periods |
| half-life | number of years it takes for 50% of an original sample of an isotope to decay |
| heterocyst | specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria |
| magnetic reversal | reversal of the polarity of Earth’s magnetic field |
| Pangaea | supercontinent formed when plate movements brought all the landmasses of Earth together |
| protobiont | aggregate of abiotically produced molecules surrounded by a membrane or membrane-like structure |
| radiometric dating | determining the ages of rocks and fossils based on the half-life of radioactive isotopes |
| ribozyme | enzymatic RNA molecule that catalyzes reactions during RNA splicing |
| serial endosymbiosis | cellular structures were formerly small prokaryotes that lived symbiotically inside larger cells |
| snowball Earth | glaciers covered the planet’s landmasses from pole to pole 750–570 million years ago |
| stromatolite | fossilized bacterial mat |
| three-domain system | classification based on three basic groups: Bacteria |
