chapter 19 Flashcards
explain the process by which fossils are formed
sediment is transferred by water and the hard parts are replaced with minerals (layer=strata)
compare the 5 different types of fossils
permineralized- minerals are carried by water and decompose around structure (bone to rock)
natural casts- flowing water removes original tissue
trace fossils- record of activity of organisms
preserved remains- found in ice or peat bog
amberpreserved- preserved in tree resin
what types of info can paleontologists determine from fossils
structure
diet
predators
environment
distinguish between relative and radioactive dating
relative- age is determined by placement of fossils, lower layers contain older examples, and index fossils are used to compare ages
radioactive- uses radioactive isotopes to age fossils, they decay into nonradioactive elements at a steady rate
what is the half life of C14
5730 years
what other isotopes can be used to date older fossils
potassium 40
uranium 238
rubidium 87
describe the nebula hypothesis
gas and dust were swirling. some collided to build up and melt together. elements then arranged according to density
what allowed the oceans and skies to become blue
oceans- oxygen reacted with the iron in the oceans and it rusted. it sunk to the bottom
sky- the ozone formed ad oxygen levels increased, methane and hydrogen sulfide decreased causing sky to become blue
what was oparins hypothesis
gases went under chemical reactions, lighting then struck primitive oceans creating life (primordial soup model)
what was sydney fox’s contribution to the history of life
suggested that protenoid microspheres could have given rise to first cells
why do scientists think RNA evolved first
simpler
can help DNA replicate
can replicate itself (ribosome)
its a catalyst
what were the first organisms formed on earth
prokaryotic heterotrophs
what led to the first mass extinction
oxygen levels increased, methane and hydrogen sulfide decreased forming ozone. many died due to the presence of oxygen
describe lynn margulis’ theory
a large prokaryote consumed a smaller. host didnt digest and smaller didnt infect. evidence comes from mitochondria & chloroplast
(both have own dna and ribosomes similar to bacteria and can replicate independent of cell)
why is sexual reproduction important to evolution
it allowed it to occur at a faster rate which led to greater genetic diversity
what about the process of fossil formation makes the fossil record so incomplete
its a unique process, so some species may not have been fossilized. soft body organisms couldnt become fossils
list the geological time scale from largest to smallest
eon, era, period
what allowed primitive earth to cool
growing atmosphere
raining for millions of years
why is the precambrian time so incomplete
there are few soft fossils because they were all soft bodied organisms
what major event took place during the cambrian period
cambrian “explosion”
organisms developed hard parts and there were inverts (jellyfish, worms, brachiopods, trilobites, sponges)
when did the first land plants evolve
ordovician and sulurian periods
which period is known as the age of fishes
devonian period
when did animals move to land
devonian period
when did reptiles and winged-insects evolve
carboniferous and permian periods
