chap 18-19 Flashcards
What does LUCA stand for?
Last Universal Common Ancestor- believed to be the ancestor of all life on earth
What five molecules were found in Earths earlier atmosphere?
methane, ammonia, water, carbon dioxide, molecular nitrogen
Why led to oxygen becoming a component of Earths atmosphere?
the evolution of photosynthetic organisms that proceed oxygen during photosynthesis
What happened to most of the water vapor found in Earth’s early atmosphere?
it condensed to form the oceans
What are the four stages in the origin of life?
stage 1: organic monomers
stage 2: organic polymers
stage 3: protocells
stage 4: living cells
what is one piece of scientific evidence to support stage 1?
Stanley Miller’s 1953 experiment
What is one piece if scientific evidence to support stage 2?
RNA- first hypothesis
what is one piece of scientific evidence to support stage 3?
micelles merging your form vesicles- membrane-first hypothesis
What is one piece of scientific evidence to support stage 4?
Cairns-Smith hypothesis- RNA and proteins evolved simultaneously
remains and traces of past life
fossils
the study of fossil record
paleontology
What does the Law of Superposition explain?
the age of fossils within a given stratum (the lower the stratum, the older the fossil)
How are fossils dated?
by using the half-life of isotopes
Name the four eras in the history of life
precambrian, Paleozoic, Mesozoic, Cenozoic
Which of these eras represents most of the geological time scale?
precambrian- 87%
What important events happened during Precambrian times?
- prokaryotic cells evolved
- oxygen added to atmosphere (first by cyanobacteria)
- eukaryotic cells evolved
- multicellular organisms evolved
What is the Endosymbiotic hypothesis used to explain?
the origin of eukaryotic cells
What important event happened during the Paleozoic Era?
- included three major mass extinctions
- organisms invaded land: evolved exoskeletons so they wouldn’t dry out; evolved hinged limbs so they could walk
- nonvascular plants like mosses evolved
- seedless vascular plants like ferns evolved
- jawless and jawed fish appeared
What important events happened during the Mesozoic Ear? At which period did they occur?
Triassic period: non flowering seed plants dominant
Jurassic period: dinosaurs became huge, mammals remained small
Crest
