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
which period is known as the age of reptiles
triassic period (mesozoic era)
when did the first birds evolve
jurassic period (close to dinosaurs)
when did flowering plants evolve
cretaceous period (another mass extinction, 1/2 disappeared)
when did dinosaurs go extinct
cretaceous period (mesozoic era)
when did whales and dolphins evolve
tertiary period (cenozoic era)
when did the ice ages occur
quarternary period (cenozoic era)
what are the characteristics of primates
long fingers and toes nails not claws arms can rotate around shoulder joints strong clavicle(stabilize shoulder) binocular vision well-developed cerebrum
what are the 2 major groups of primates
prosimians (lemurs, lorises, tarsiers)
anthropoids (human-like primates)
distinguish between new and old world monkeys
new world- central and south america, live almost entirely in trees, have prehensile tails (spider monkey)
old world- africa and asia, sometimes in trees, lack prehensile tails (langurs, macagues)
what makes humans different from other hominoids
changes in skeleton allowed for bipedalism
opposable thumbs
larger brains
list the ancestors of humans and characteristics of each
Homo habilis- used tools Homo ergaster- larger brain, downward facing nostrils Homo erectus- migrated out of africa Homo neaderthalensis- cave man Homo sapien- skeletons identical to ours
how did members of the genus Homo change over time
used tools
developed larger brain
smaller jaw
migrated
describe how miller and urey tested oparins hypothesis
they boiled a flask of water
added methane, ammonia, and hydrogen to water vapor
passed gases through electrodes to simulate lightning
passed through condensation chamber cooling and forming drops
produced 21 amino acids
