Chapter 25 Flashcards
___________________ represents the sequence and the dates of the major events the history of earth
geological time scale
three eons compromise earth’s history
- archean
- proterozoic
- phanerozoic
most ancient eon
archaean
archaean and proterozic are collectively referred to as
precambrian
middle eon
protereozoic
current eon
phanerozoic
each eon is divided into
eras
three eras of the phanerozoic eon
- paleozoic
- mesozoic
- cenozoic (current)
eras are divided into
periods
periods are divided into
epochs
age of earth
4.6 billion
the boundaries of geological time scales eon, eras, and certain periods correspond to
- mass extinction events
- a major adaptive radiation (rapid speciation) of survivors
the sequence of fossils
provides relative dates not numerical dates
____________ enables determination of numerical dates
radiometric dating
radiometric dating is based on the decay of
radioactive isotopes
while alive organisms assimilate different isotopes of an element into their bodies in the same proportion as the isotopes abundance in the environment
once dead, organisms stop assimilating isotopes, the non radio isotopes remain fixed but he radioactive isotopes begin to decay
a radioactive isotopes ________________ is the number of years it takes for half of the isotope to decay
half-life
half life is a _____________________
constant value
isotopes of carbon include
C12
C13
C14
Radio active carbon ____________
half-life: ________________________
C14
5730
example a fossil is discovered with 1/4 the carbon 14.
The fossil has gone through 2 half lives
1/2 * 1/2 =1/4
The fossil is 11460
other radioactive isotopes live much longer so older dates can be determines example ____________________________
including uranium 4.5 billion year half life
each existed without life for
1.1 billion years. The atmosphere and oceans had yet to form.
life first evolved
3.5 billion years ago
all organism arise from preexisting organisms
and all cells arise from pre existing cells
early each was a very different environment
the original atmosphere consisted of very different collection of gasses than todays atmosphere
some of the early atmosphere gasses were
nitrogen, ammonia, carbon dioxide, methane, hydrogen, hydrogen sulfide, water vapor, BUT NO OXYGEN
the primitive oceans were
much warmer
there was much _______________ on early earth
volcanic and lightening activity
biologists agree on a four stage sequence of events by which life could have evolved from non life as each stage is backed by supporting evidence
- synthesis of organic monomers from inorganic molecules
- the synthesis of polymers from monomers
- the packaging of polymers into membrane cells
- the replication of protocells
synthesis of monomers
opaline and haldane
miller and urey
hypothesized that organic monomers could be formed from inorganic molecules under conditions of earth’s earth atmosphere
opaline and haldane
constructed an experiment apparatus to simulate early earth and test opaline and haldane’s hypothesis
miller and urey
miller and urey were able to produce a
single amino acid
organic monomers may also have formed from inorganic molecules
- near deep sea hydrothermal vents
- in space vents carried to earth by mediorites
polymers were synthesized by
solutions of monomer exposed to hot rocks will polymerize
______________ are “pre cells”, membranous droplets that maintain an internal composition difference from that of their surroundings environment
protocells
protocols would have resulted from polymers being packaged within spontaneously-forming
lipid aggregates
DNA requires ____________________ while enzymes are synthesized using
enzymes (proteins) for replication,
DNA as a template
Which cam first DNA or Proteins
RNA
RNA molecules that serve as enzymes _______________. The could catalyze chemical reactions including their own replication
ribosimes
over time chemical evolution gave rise to
biological evolution
-The proteocells able to replicate themselves were selected for, ultimately resulted in true cells
early organisms were
- heterotrophic
- anerobic
- aquatic
- unicellular
define anerobic
oxogen was not present so fermentation was the metabolic pathway
define heterotrophic
consuming the small organic molecules present in the seas
heterotrophic prokaryotes began to
deplete the available nutrients in primordial seas
once autotrophy evolved those prokaryotes that could make they own food gains a selective advantage these prokaryotes were known as
cyanobacteria- earths first photosynthesizes
oxygen began accumulating in the atmosphere
2.7 bya
__________ was a poison to most anaerobic prokaryotes. The evolution of cellular respiration as a metabolic pathway led to aerobic prokaryotes were all a result of the introduction of this
oxygen
2.5 bya
a mass extinction occurred as increasing oxygen levels resulted in the death of most anaerobic prokaryotes
archean and protozoic boundary \
an adaptive radiation of aerobic survivors then followed
2.5 bya- 542 mya
the first unicellular eukaryotic organisms evolved 2.1 bya
proterozoic eon
prokaryotic inhabited earth alone for
1.4 bya alone
the first eukaryotic organisms were
protists
eukaryotic evolution began with an ancestral prokaryote that
- was surrounded by a plasma membrane
- DNA in its nucleoid region
the infolding of the plasma membrane gave rise to
the nucleus and the endomembrane system
endomembrane system organelles
- nuclear envelope
- endoplasmic reticulum
- golgi apparatus
in _____________________ a smaller prokaryotic cell (with nucleus and endomembrane system)
endosymbiosis
engulfed aerobic heterotrophic prokaryotes gave rise to
mitochondria
engulfed autotrophic prokaryotes gave rise to
chloroplasts
mitochondria and cellular respiration is advantages because
it increases oxygen
chloroplasts were advantages because
photosynthesis produced its own food
chloroplasts and mitochondria are surrounded by
a double membrane
Chloroplasts contain______________ not associated to histones and replicated by _____________
their own DNA
Binary fission
chloroplasts are closely related to
cyanobacteria
mitochondria are closely related to
alpha-proteo bacteria
multicellular in eukaryotic cells evolved ________________
1.5 by a during proterozoic era
first multicellular organisms ____________________ however they were not abundant until 600 mya
jelly, algae, and sponges
________________________ served as a link between unicellular and multicellular organisms
colonial organisms
a __________________ is an assemblage of unicellular organisms that do exist as a multicellular organisms though their is no division of work
a colony of cells
specialization of individual cells within a colony resulted in
tissues
a true multicellular organisms
results when a cell is dependent upon one another
no mass extinction but a huge adaptive radiation
proterozoic and phanerozoic boundary
this adaptive radiation resulted in an explosion of life of the current animal body
cambrian explosion
_________________ resulted from a grater availability of oxygen as well as responses to increases predator prey interactions
cambrian explosion
542 mya-251 mya
began with the first period of era
-origin of the first vertebrate animals
phanerozoic eon (paleozoic era)
original vertebrates
fish
colonization of land by first terrestrial organisms occurred
488 may nonvascular plants
460 may arthropods developed
arachnids and centipede and milapeds
360 mya the first vertebrates developed
amphibians
what enabled colonization of the land
oxygen gas reacts in the upper atmosphere to form ozone gas. The ozone layer shields earths surface from the suns damaging rays. Prior to ozone the only way to avoid thee rays was under water.
the first forests of vascular plants appeared during the
carboniferous period— 350 mya
the collision of all landmasses formed the supercontinent pangea this obliterated much marine life and had major consequences for terrestrial life as well
permian extinction-251 mya
the triassic jurassic and cretaceous periods were the three periods of the ear. Reptiles notably dinosaurs were dominant land animals. Seed plants were the dominant plants
phanerozoic eon- mesozoic era
the first forests of vascular plants appeared amphibians and spiders
Phanerozoic eon- Paleozoic era
the cretaceous was the final period of the era, caused by an asteroid impact in the gulf of mexico
cretaceous extinction
an adaptive radiation of several groups organisms has occurred during this era
- mammals
- birds
- insects
- flower plants
phanerozoic eon- cenozoic era
all of these groups originated during the mesozoic but did not become abundant until the cenozoic
-mammals diversified due to the environmental opportunities left vacant by the extinct dinosaurs
-insects and flowering plants diversified by way of coevolution
two species exerting selective pressures on each other, resulting in both evolving each other
coevolution
___________________ appeared 195.000 years ago
homo sapiens
homo sapiens developed during the
piestetocene epoch
biologists believe that extinction rates to be 100-1000 times the normal rate
this could be at the level of another mass extinction
these extinctions are caused by
humans
- climate change
- habitat loss
- overexploitation
- introducted invasive species
- pollution
- climate change
