Chapter 25 Flashcards
what are some examples of macroevolutionary changes represented through fossils
the emergence of terrestrial vertebrates, the origin of photosynthesis, long term impacts of mass extinctions, key adaptations such as flight
describe the process that some think may have produced the first cells
abiotic synthesis of organic molecules such as amino acids and nitrogenous bases, joining of those molecules into macromolecules such as proteins and nucleic acids, the packaging of these molecules into protocells, and the origin of self-replicating molecules
what did A.I. Oparin and J.B.S. Haldane hypothesize about the early atmosphere
that is was a reducing environment
what did Stanley Miller and Harold Urey do
conducted lab experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible
Aside from a reducing atmosphere, the first organic molecules may have been formed …
near submerged volcanoes and deep-sea vents, meteorites
what are protocells
aggregates (clumps of molecules) of abiotically produced molecules surrounded by a membrane or membrane-like structure
what are liposomes and how are they formed
they are small membrane-bounded droplets that can form when lipids or other organic molecules are added to water
the first genetic material was probably …
RNA
the relative age of fossils can be estimated through…
the relative ages of fossils
the absolute ages of fossils can be determined by …
radiometric dating
this is the time required for half the parent isotope to decay
half-life
how can magnetism of rocks be used to provide dating information
every 300,000 years reversals of the magnetic poles leave their record on rocks throughout the world
the geologic record is divided into what three eons
the Archaean, the Proterozoic, and the Phanerozoic
this eon encompasses multicellular eukaryotic life
phanerozoic
what are the three eras that the phanerozoic is divided into
the Paleozoic, the Mesozoic, and Cenozoic
theses are rock-like structures composed of many layers of bacteria and sediment - the oldest known fossils
stromatolites
how old are stromatolites
3.5 billion years
what was the oxygen revolution
O2 began accumulating in the atmosphere and rusting iron-rich terrestrial rocks, this posed a challenge for life, provided an opportunity to gain energy from light, and allowed organisms to exploit new ecosystems
how old are the oldest fossils of eukaryotic cells
2.1 billion years
describe the hypothesis of endosymbiosis
mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes within larger host cells
this is a cell that lives within a host cell
endosymbiont
what is serial endosymbiosis
the thought that mitochondria evolved before plastids through a sequence of endosymbiotic events
what is some of evidence that supports an endosymbiotic origin of mitochondria and plastids
similarities in inner membrane structures and functions, these organelles transcribe and translate their own DNA, their ribosomes are more similar to prokaryotic than eukaryotic ribosomes
what is the oldest known fossil of a multicellular eukaryote and how old is it
algae, 1.2 billion years
this refers to the sudden appearance of fossils resembling modern phyla in the Cambrian period
Cambrian explosion
what did the Cambrian explosion provide
the first evidence of predator-prey interactions
these are the most widespread and diverse land animals
arthropods and tetrapods
tetrapods evolved from _______
lobe-finned fishes
the land masses of Earth have formed a supercontinent at how many points in time
3
earth’s continents move slowly over the underlying hot mantle through the process of ____________
continental drift
what were the effects of the formation of the supercontinent Pangaea about 250 million years ago?
a reduction in shallow water habitat, a colder and drier climate inland, changed in climate as continents moved toward and away from the poles, changes in ocean circulation patterns leading to global cooling
in each of the five mass extinction events, more than ___% of Earth’s species became extinct
50
this is the extinction between the Paleozoic and Mesozoic eras
Permian extinction
this is the extinction that separates the Mesozoic from the Cenozoic
Cretaceous mass extinction
the presence of _____ in sedimentary rocks suggests a meteorite impact about ____ million years ago
iridium, 65
how does the current rate of extinction compare to the typical background rate
it is about 100 to 1000 time greater
this is the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities
adaptive radiation
example of adaptive radiation
mammals expanded in diversity and size after the extinction of the dinosaurs
adaptive radiation occur when ________
organisms colonize new environments with little competition (Hawaii islands)
this is an evolutionary change in the rate or timing of developmental events
heterochrony
in __________, the rate of reproductive developments accelerates compared with somatic development
paedomorphosis
these determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged
homeotic genes
these are a class of homeotic genes that provide positional information during development
hox genes
give an example of an error in a hox gene
when hox genes are expressed in the wrong location, body parts can be produced in the wrong location, in crustaceans a swimming appendage can be produced instead of a feeding appendage
these are structures that evolve in one context but become co-opted for a different function
exaptations
