25 Flashcards
half life
the time required for half the parent isotope to decay
endosymbiosis
proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells
cambrian explosion
The Cambrian explosion refers to the sudden appearance of fossils resembling modern phyla in the Cambrian period
continental drift
Earth’s continents move slowly over the underlying hot mantle
Adaptive radiation
the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities whose adaptations allow them to fill different ecological roles
usually occurs after mass extinctions
Heterochrony
is an evolutionary change in the rate or timing of developmental events
paedomorphosis
retention into adulthood of features that were solely juvenile in ancestors
Homeotic genes
determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged
The geologic record is divided into
the Archaean, the Proterozoic, and the Phanerozoic eon
why did oxygen begin to accumulate in the atmosphere (oxygen revolution)?
cyanobacteria were doing photosynthesis so they were adding oxygen to the atmosphere
what are the 4 steps that led to life on earth?
- the abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogeneous bases
- the joining of these small molecules into macromolecules, such as proteins and nucleic acids
- the packaging of these molecules into PROTOCELLS, droplets with membranes that maintained an internal chemistry different from that of their surroundings
- origin of self-replicating molecules that eventually made inheritance possible
stromatolites
layered rocks that form when certain prokaryotes bind thin films of sediment together
earliest evidence of life - 3.8 billion years ago
during Early Archean
relative dating
is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers.
absolute dating
is the numeric age of a layer of rocks or fossils. Absolute age can be determined by using radiometric dating.
how old are oldest known fossils?
the cyanobacteria or “blue-green algae,” have left a fossil record that extends far back into the Precambrian - the oldest cyanobacteria-like fossils known are nearly 3.7 billion years old
in the Archaean eon
How old are the oldest eukaryotic fossils?
proterozoic eon
1.8 billion years ago
The oldest known fossils of multicellular eukaryotes are of small algae that lived about 1.2 billion years ago
How many mass extinction events have been documented in the fossil record over the past 500 million years?
five mass extinctions
give an example of adaptive radiation
– Mammals underwent an adaptive radiation after the extinction of terrestrial dinosaurs
– The disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size
adaptative radiation on the hawaiian island
The geologic record is divided into 3 eons. What are these eons and what is the relative age of each eon?
Archean
Proterozoic
Phanerozoic
The Archean and Proterozoic eons lasted about 4 billion years.
The Phanerozoic eons was about 600,000 years
The Cambrian explosion marks the relatively “sudden” appearance of many animal phyla approximately 542 million years ago. Approximately what percentage of Earth’s history has occurred BEFORE the appearance of animals?
87%
Which of the following is a rich source for the earliest prokaryote fossils?
stromatolites
radiometric dating _____
allows us to indirectly date fossils up to billions of years old based on minerals in surrounding volcanic strata
You discover three fossil organisms and want to determine their dates. You measure the percentage of carbon-14 (half-life of 5,730 years) remaining in the fossils. Which of the following correctly places them in order from oldest to youngest?
A = 38.7 B = 77.0 C= 52.1
A, C, B
oldest to youngest
38.7, 52.1, 77.0
38.7% is oldest because it has the least amount of the half life remaining meaning it has gone through more half lives already
You discover a series of fossil organisms and want to determine their dates. You decide to use carbon-14 dating (half-life of 5,730 years). Based on the table below, about how old are fossils A and B?
2,865
5,730/2 = 2,865
When did the first prokaryotes arise, according to the fossil record?
3.5 billion
One species of finch colonizes an island and, over a relatively short period of time, speciates into several different finch species. This is an example of
adaptive radiation
The Cambrian explosion marks the relatively “sudden” appearance of many animal phyla approximately 542 million years ago. Approximately what percentage of Earth’s history has occurred since the appearance of animals?
13%
Which of the following is a reasonable prediction concerning plate tectonics and continental drift?
Continents should eventually re-aggregate into a supercontinent before breaking up again.
A basic tenet of evolution by natural selection is that species should continually become more fit for their environment. What, then, can account for extinction?
The environment changes more rapidly than species can adapt.
When was the largest mass extinction in the history of our planet?
252 millions years ago
perminian extinction
The hundreds of varied fruit fly species on the Hawaiian Islands arose through adaptive radiation. Which piece of evidence would best support this claim?
The Hawaiian fruit fly species are more closely related to each other genetically than they are to non-Hawaiian fruit flies.
According to geological evidence, which event may have triggered the Permian mass extinction?
volcanic eruptions may have triggered a series of catastrophic events that led to perminian mass extinction
what were the first single celled organisms?
stromatolites
oxygen revolution
By about 2.7 billion years ago, O2 began accumulating in the atmosphere and rusting iron-rich terrestrial rocks (from cyanobacteria)
- Provided opportunity to gain energy from light
- Allowed organisms to exploit new ecosystems
describe the evolution of eukaryotes
The hypothesis of endosymbiosis proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells
-The prokaryotic ancestors of mitochondria and plastids probably gained entry to the host cell as undigested prey or internal parasites
•In the process of becoming more interdependent, the host and endosymbionts would have become a single organism
•Serial endosymbiosis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
evolution is not ____
goal oriented.
protocells
organic compounds can spontaneously assemble into protocells- membrane bound droplets that have some properties of life
The Origin of Multicellularity
The evolution of eukaryotic cells allowed for a greater range of unicellular forms.
- A second wave of diversification occurred when multicellularity evolved and gave rise to algae, plants, fungi, and animals
- Comparisons of DNA sequences date the common ancestor of multicellular eukaryotes to 1.5 billion years ago
Which organelles likely originated from endosymbiosis?
The hypothesis of endosymbiosis proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells
fossilized stromatolites ____
resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays.
The oxygen revolution changed Earth’s environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?
the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?
India was a separate continent until 45 million years ago.
Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.
genetic drift
Which of the following steps has not yet been accomplished by scientists studying the origin of life?
formation of protocells that use DNA to direct the polymerization of amino acids
A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of
a change in a developmental gene or in its regulation that altered the spatial organization of body parts.
A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air breathing organ (a simple lung) of an ancestral fish is an example of
exaptation
exptation
Exaptation and the related term co-option describe a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another.
fossil records show _____ changes over large time scales
macroevolutionary
what is a protocell?
droplets with membranes that maintained an internal chemistry different from that of their surroundings
what are limitations of fossil record?
- taxa bias
- habitat bias
- temporal bias
- abundance bias
absolute ages of fossils can be determined by ______
radiometric dating
_____ rocks are the richest source of fossils
sedimentary
fossil record is based primarily on what?
strata- sequence in which fossils have accumulated in sedimentary rock layers
what can fossils tell us about the history of life?
The fossil record provides evidence about the history of life and past environments on Earth. The fossil record also shows that different groups of organisms have changed over time.
The first single-celled organisms
stromatolites - 3.7 billion years ago
The evolution of photosynthesis
2.7 billion years ago
what are the eras?
– Paleozoic era
– Mesozoic era
– Cenozoic era
when was the oxygen revolution?
2.7 to 2.2 billion years ago
The colonization of land
Fungi, plants, and animals began to colonize land about 500 million years ago
evidence for the endosymbiotic origin of plastids and mitochondria
- Similarities in inner DNA membrane structures and functions
- Division is similar in these organelles and some prokaryotes
- These organelles transcribe and translate their own DNA
- Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes
at what points in time did the land masses of Earth have form a supercontinent?
1.1 billion, 600 million, and 250 million years ago
continental drift
Earth’s continents move slowly over the underlying hot mantle
when was pangea
250 million years ago
what defines the boundary between the Paleozoic and Mesozoic eras?
The Permian extinction
The Permian extinction: when was it and what percentage of species extinct and what caused it?
This mass extinction occurred in less than 5 million years and caused the extinction of about 96% of marine animal species
This event might have been caused by volcanism, which lead to global warming, and a decrease in oceanic oxygen
what separates the Mesozoic from the Cenozoic and when was it?
The Cretaceous mass extinction was 65.5 million years
– Organisms that went extinct include about half of all marine species and many terrestrial plants and animals, including most dinosaurs
Mass Extinction can pave the way for ______
adaptive radiations
what are examples of adaptive radiation?
– Mammals underwent an adaptive radiation after the extinction of terrestrial dinosaurs
– The disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size
– Other notable radiations include photosynthetic prokaryotes, large predators in the Cambrian, land plants, insects, and tetrapods
_____ studies the evolution of developmental processes in multicellular organisms
evo-devo
Heterochrony
is an evolutionary change in the rate or timing of developmental events
Heterochrony
is an evolutionary change in the rate or timing of developmental events
Heterochrony can alter the timing of reproductive development relative to the development of nonreproductive organs
paedomorphosis
large morphological differences can result from genes that alter the rate, timing and spatial pattern of a species may retain body features that were juvenile structures in an ancestral species
Homeotic genes
determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged – Hox genes are a class of homeotic genes that provide positional information during development – If Hox genes are expressed in the wrong location, body parts can be produced in the wrong location
A SKELETON IS FOUND TO CONTAIN 1/8TH OF ITS ORIGINAL RADIOACTIVE MATERIAL.
How many have lives have gone by?
After one half life = 1/2 remains
After 2 half lives = 1/4 remains
After 3 half lives = 1/8 remains
So our skeleton has existed for 3 half lives.
(1/2)^3
prokaryotes were earths sole inhabitants from when to when?
3.5 billion to 2.1 billion
the oldest known fossils of multicellular eukaryotes are ____
small algae that lived about 1.2 billion years ago
however DNA sequencing suggest that their origin date may be older (1.5 bya or more!)
the evolution of photosynthesis would have occurred prior
to the “oxygen revolution” occurred from 2.7 to 2.2 billion years ago
____ of earth’s history occurred before the appearance of animals.
87 - 89%
