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Biology - Chapter 14
Terms in this set (39)
When do scientists believe the earth formed?
Is there any direct evidence of earth's earliest history?
Where do scientists believe life originated?
Is the fossil record complete?
What is a fossil?
evidence of an organism that lived long ago that is preserved in Earth's rocks
What are the five types of fossils?
trace fossils, cast, mold, petrified / permineralized fossils, and amber-preserved or frozen fossils
What are the conditions needed for a fossil to form?
hard parts, rapid burial, anoxic conditions
What is a paleontologist?
a scientist who studies ancient life
What are the three criteria that aid in becoming a fossil, and how do they aid in becoming a fossil?
- hard parts - bones, teeth, shells, chiton (in exoskeleton)
- rapid burial - decomposition slows down, scavengers can't get to it, protection (helpful if in mud, sand, or clay)
- anoxic conditions : little or no oxygen present (less bacteria to break down tissues)
What is relative dating?
the science of determining the relative order of past events, without necessarily determining their absolute age
What are the four laws of relative dating?
Law of Superposition, The Cross-Cutting Law, Law of Inclusions, and Law of Folds or Tilts
What is radiometric dating?
Scientists utilize radioactive isotopes in rocks to find specific ages of rock & compare how much radioactive isotope is in a rock compared with its daughter nuclei (what the isotope decayed into)
What radioactive isotope is used to date once-living organisms? What is it's half-life?
Carbon-14, half life 5730 years
What are the four main eras of the geologic time scale in order of oldest to youngest?
Precambrian, Paleozoic, Mesozoic, and Cenozoic
What is the oldest fossil?
stromatolite - dome-shaped structures - evidence of existence of photosynthetic organisms
(this modern organism resembles cyanobacteria)
What structures helped put oxygen into the atmosphere?
What were the main organisms in the Precambrian time?
prokaryotes and eukaryotes
What happened during the Paleozoic?
Cambrian Explosion - sudden appearance in the fossil record of complex animals with mineralized skeletal remains (diversity)
What was important about the Cambrian period?
accounts for about 87% of earth's history
What were the main organisms of the Paleozoic?
trilobites, archaeocyathids (like armored sponges), and brachiopods - or vertebrae, fish, and land plants
What happened at the end of the Paleozoic?
the Permian extinction
What were the main organisms of the Mesozoic?
dinosaurs, small mammals, birds, and flowering plants
What happened at the end of the Mesozoic?
a mass extinction (smaller than one at end of Permian, almost 2/3 of all living species became extinct)
What is the idea of Pangea?
theory of continental drift - one large supercontinent (when all continents were joined into one landmass like puzzle pieces), broke apart into Laurasia and Gondwana
What five pieces of evidence support the idea of Pangea?
- Shape of continents fit together like puzzle pieces
- Climate clues from tropical fossils being found in polar regions
- Similar fossils between edges of continents
- Similar rocks and minerals between edges of continents
- Magnetic reversal at sea floor spreading locations
What were the main organisms of the Cenozoic?
mammals, primates, modern human species first appeared
What is the idea of spontaneous generation?
idea that nonliving material can produce life
Who disproved spontaneous generation?
Who is Francesco Redi?
(1668) disproved spontaneous generation in large organisms, and experimented with meat & maggots
Who is Louis Pasteur?
disproved the idea of virtual force in the air for spontaneous generation of microorganisms
What is biogenesis?
idea that living organisms came only from other living organisms
Compare biogenesis and spontaneous generation
biogenesis - living produce life
spontaneous generation - nonliving produce life
Who was Alexander Oparin, what did he theorize?
1930's Russian Scientist - believed life began in oceans & that energy from the sun, lightning, and Earth's heat trigged chemical reactions to produce the small organic compounds. Then rain washed molecules into oceans to form the primordial soup
Who were Stanley Miller and Harold Urey? What was their famous experiment?
(1953) tested Oparin's hypothesis : mixed water vapor (steam) with ammonia, methane and hydrogen gases (believed to be in early atmosphere) - sent an electric current through it - cooled mixture and one week later analyzed the results. Found presence of amino acids, sugars, and other small organic molecules - Supported Oparin's hypothesis!
Who was Sidney Fox, what was his famous experiment?
1992 American scientist that demonstrated how first cells might have occurred, heated solution of amino acids and produced protocells
What are Archeabacteria?
prokaryotic, live in harsh environments (deep sea vents, hot springs, etc.)
Why did photosynthesizing prokaryotes come after chemosynthetic prokaryotes?
What is the endosymbiont theory?
proposed that eukaryotes evolved through a symbiotic relationship between ancient prokaryotes
Who is Lynn Margulus? What was her famous theory?
1960's American biologist - proposed that eukaryotes evolved through a symbiotic relationship between ancient prokaryotes -
prokaryote ingested some aerobic bacteria and aerobes became mitochondria & some prokaryotes also ingested some cyanobacteria, which contain photosynthetic pigments - became chloroplasts
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