Ch. 25 Quiz Flashcards
an RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing
ribozymes
a method for determining the absolute ages of rocks and fossils, based on the half-life of radioactive isotopes
radiometric dating
the amount of time it takes for 50% of a sample of a radioactive isotope to decay
half-life
the division of Earth’s history into time periods, grouped into three eons-Archaean, Proterozoic, and Phanerozoic-and further subdivided into eras, periods, and epochs
geologic record
layered rock that results from the activities of prokaryotes that bind thin films of sediment together
stromatolites
a process in which a unicellular organism engulfs another cell, which lives within the host cell and ultimately becomes an organelle in the host cell
endosymbiosis
a hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells
serial endosymbiosis
a relatively brief time in geologic history when large, hard-bodied forms of animals with most of the major body plans known today appeared in the fossil record
Cambrian explosion
period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill vacant ecological roles in their communities
adaptive radiations
evolutionary change in the timing or rate of an organism’s development
heterochrony
the retention in an adult organism of the juvenile features of its evolutionary ancestors
paedomorphosis
any of the master regulatory genes that control placement and special organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells
homeotic genes
a collection of abiotically produced molecules surrounded by a membrane or membrane-like structure
protobionts
