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Biology Chapter 19 Questions
Terms in this set (79)
How do scientists use fossils to study Earth's history
From the fossil record, paleontologists learn
about the structure of ancientorganisms, their environment, and the way they lived.
What are some patterns in which evolution has occurred
Evidence shows that evolution has often
proceeded at different rates for different organisms at different times over the long
history of life on Earth. Patterns of macroevolution
include speciation, extinction, adaptive radiation, convergent evolution, and coevolution.
What happened during Earth's early history
Early Earth had little or no oxygen in
its atmosphere. Around 2.2 billion years ago,
photosynthetic organisms evolved and began producing oxygen. Early multicellular
organisms underwent adaptive radiations that led
to great diversity.
________ are preserved remains or traces of ancient life. They are the most important source of information about extinct species. An _______ species is one that has died out. Most fossils are preserved in ____________ rock. Sediments build up over time and bury the remains and traces of dead organisms. Scientists who study fossils are called ____________.
__________ dating and ____________ dating are used to determine the ______ of fossils
_________ __________ establishes the relative age of fossils. Fossils are deeper rock layers are assumed to be ________ than fossils from rock layers closer to the surface. ________ _________ represent species that lived for a short period of time but over a wide geographic range. Index fossils can help determine the relative ages of rock layers and their fossils
__________ ____________ determines a fossil's approximate age in years by finding the proportion of radioactive to nonreactive isotopes in a sample. Radioactive isotopes in fossils and rock layers decay, or break down, at a steady rate called a half-life. A _________ _________ is the length of time needed for half of the radioactive atoms in a sample to decay. A fossils age is calculated from the half-life and the amount of ____________ ________ the fossil contains
The _______ _______ _________ is a time line of Earth's history based on relative and absolute dating. The scale begins with the __________. Geologic time is divided into four eons: the _____________, _________, ___________-, and _______________
geologic time scale
Hadean; Archean; Proterozoic; and Phanerozoic
The Phanerozoic eon is divided into three eras: ____________, ___________, ___________. Each era is further divided into smaller lengths of time called ____________--
Paleozoic; Mesozoic; and Cenozoic
__________, geological, ________ and biological processes have affected the history of life on Earth. The impact of objects from space has affected the __________ climate.
Earth's climate has changed often in course of its history. Small temperature shifts can bring about heat waves and ice ages which have great effects on living things. _________ ________ is a theory that Earth's outermost layer is divided into plates that move. The movement, called _________ _________, has transformed life on Earth through the formation of mountain ranges, supercontinents, and other geologic features
Scientists who study fossils are called __________________. Most fossils are found in layers of __________ rock. Species that die out are said to be ____________
What is a fossil record
it is the total collection of fossils on Earth, plus the information about past life inferred from fossils
What information does the fossil record provide
It provides evidence about the history of life on Earth including how organisms have
changed over time. It tells about the structures of ancient organisms, their environment, and the way they lived.
How are the steps on how fossils are found.
Water carries small rock particles to lakes and seas. Dead organisms are buried by layers of sediment, which forms new rock. The preserved fossil remains may later be discovered and studied
What is an index fossil? What do index fossils reveal about other material found with them
Index fossils are distinctive fossils used to establish and compare the ages of rock layers and the fossils they contain. Useful index fossils existed for a relatively short period of time and were distributed over a wide area. Anything found in a rock layer near an index fossil is assumed to have existed at approximately the same time
Fossil A is found in a layer of rock above a layer containing Fossil B. Which fossil is older and why
Fossil B is older. Newer layers of rock lie usually above older layers
List the two techniques paleontologists use to determine the age of fossils
relative dating, radiometric dating
What is a half-life
It is the length of time required for half of the radioactive atoms in a sample to decay
How do scientists calculate the age of a sample using radiometric dating
They measure the amount of remaining radioactive isotopes it contains. The smaller the amount is, the older the sample is
A species that is easily recongnizable, existed for a relatively short period of time and covered a wide geographic area may be used as a ______________
The same index fossil is found in rock layers A and B that are separated by several miles. What can you infer about the relationship between the rock and layers
Layers A and B are probably about the same age.
How might an asteroid impact change Earth's climate
When the asteroid strikes Earth, it would throw up a great deal of debris into the atmosphere. The debris would block much of the sun's light, thus causing global temperatures to fall and decreasing the amount of plant life that could survive on Earth
Explain the theory of plate tectonics and tell how it has affected the distribution of fossils and organisms
According to the plate tectonics theory, Earths outermost layer is divided into huge plates that have moved in the past and continue to move. The movement of the plates is called continental drift. Continental drift affected the distribution of fossils and living organisms. As the continents drifted apart, they carried organisms with them.
What are some aspects of a species' evolution that can't be studied using fossil evidence? Why don't fossils provide information about these characteristics
fossils can't usually provide information about the soft tissues of an organism because soft tissues rarely become fossilized. Also, fossils rarely provide information about interactions among organisms and thus tell us little about animal behavior
____________ ____________ are grand transformations in anatomy, phylogeny, ecology, and behavior that usually take place in clades larger than a single species. If the rate of speciation in a clade is equal to or greater than the rate of extinction, the clade will continue to _____________. If the rate of extinction in a clade is greater than the rate of speciation, the entire clade will eventually become _______________--
____________ _______________ is extinction caused by the slow process of natural selection. ___________ ___________ affect huge numbers of species over a relatively short time
Evidence shows that evolution has occurred at different rates for different organisms at different times. The idea that evolution occurs slowly and gradually is called ______________. In ___________ _____________, long periods of little or no change are interupted by short periods of rapid change
__________ ___________ is the process in which a single species evolves into diverse species that live in different ways. _________ _____________ is the process in which unrelated species come to look alike because they have evolved similar adaptations in response to similar environments
_____________ is the process by which two species evolve in response to changes in each other over time. For example, plants evolved ____________ that protected them from insects. In response, insects evolved ways of protecting themselves from the poisons
The __________________ in a clade must be equal to or greater than the rate of extinction in order for a clade to survive. Immediately after a mass extinction, _____________ is dramatically reduced. Large-scale evolutionary changes that usually take place over long periods of time are referred to as _______________________. Many species disappear rapidly during a _________________
rate of speciation
What are possible causes of mass extinction
Some possible causes of mass extinction include a huge asteroid striking Earth, many
large volcanoes erupting, continents changing position, and sea levels changing
What effects have mass extinction had on the history of life
The disappearance of so many species leaves behind empty niches in an ecosystem. New species often evolve to fill these niches.
Horseshoe crabs have changed little in structure from the time they first showed up in the
fossil record. Which pattern of evolution do horseshoe crabs likely follow—gradualism or
punctuated equilibirum? Explain your answer.
Horsehoe crabs follow a punctuated equilibrium pattern. In punctuated equilibirum,
there are long periods of little or no change interrupted by rapid change. If horseshoe
crabs were following a gradualism pattern, you'd expect them to be changing slowly and constantly.
Why does rapid evolution occur more often in small populations
Because genetic changes can spread more easily in small populations. This happens in
both genetic drift and genetic bottlenecks
Compare and contrast punctuated equilibrium and gradualism
Punctuated Equilibrium: Evolution that occurs
with periods of inactivity followed by periods of rapid changes
Gradualism: Evolution that occurs at slow and steady pace over time
Both: Organisms change over time.
The process in which a single species or a small group of species evolves into diverse forms that live in different ways is called __________ ___________. The extinction of most ___________ contributed to the adaptive radiation of mammalas. A ____________ and ________ is an example of a convergent evolution. The process by which unrelated organisms come to resemble one another is ______________ ___________
shark's fin and dolphin's limb
What is coevolution
coevolution is the process by which two species evolve in response to changes in each other over time
. 'I'iwi birds have long, curved beaks that enable them to get nectar from tubular lobelia
flowers. Explain how these two species might have coevolved. What might happen if the
lobelia die out?
The beak of the 'i'iwi bird has coevolved to match the shape of the lobelia flowers.
Over time 'i'iwi birds with long, curved beaks were more successful at surviving and
producing offspring than birds without these traits. If the lobelia flowers die out, the
'i'iwi birds would have to adapt to a new food source or they would also die out.
What is the relationship between environmental change and the following macroevolutionary patters: speciation, mass extinction, and adaptive radiation
The success of a new species depends on its ability to cope with the conditions of a
changing environment. During mass extinctions, numbers of species become extinct when their environment suddenly changes drastically. Adaptive radiation is indirectly related to environmental change. Adaptive radiation may occur when species migrate to a new environment or after a large extinction clears the environment of a large number of organisms
Earth's early atmosphere contained _______ gases. The atmosphere contained little or no _______________
In the 1950s, ____________ __________ and _______ ________ set out to determine if organic molecules could assemble under eartly Earth conditions. they filled a container with water and gases that they thought represented the composition of Earth's early atmosphere. They passed electric sparks through the mixture to stimulate _____________. Soon, _________ _______ formed. The experiment showed that molecules needed for life could have arisen from __________ ________
Stanley Miller and Harold Urey
Under some conditions, large organic molecules from tiny bubbles called ________ ____________. Structures similar to them might have become the first ________ cells. _________ and _____ could have evolved from simple organic molecules
RNA and DNA
the first known life forms evolved about __________ years ago. They were single celled and looked like bacteria. Eventually, ____________ bacteria became common. During photosynthesis, the bacteria produced oxygen. The oxygen accumulated in the ______________. The rise of oxygen drove some life forms to ____________. At the same time other life forms evolved that depended on oxygen
The first eukaryotes, or organisms with nuclei, evolved from prokaryotes that began to develop internal ___________ _________. One explanation for how eukaryotes evolved is the ___________ _______________. this theory proposes that smaller prokaryotes began living inside larger cells and evolved a symbiotic relationship with the larger cells
___________ ____________ evolved after eukaryotic cells. It increased __________ _____________, so evolution could occur more quickly. Several hundred million years after sexual reproduction evolved, ____________ life evolved
what are proteinoid microspheres
They are tiny bubbles formed from large organic molecules that have some characteristics
of living cells.
Why do scientists think that RNA may have evolved before DNA
Experiments show that small sequences of RNA could have formed and replicated on
their own in the conditions present on early Earth.
What was the purpose of Miller and Urey's experiment
to determine whether organic molecules could assemble under the conditions of early Earth
Explain the results of the Miller-Urey experiment. What did these findings suggest
The experiment produced several amino acids, which suggested that mixtures of organic compounds could have arisen from substances found on early Earth. Evidence now suggests that the composition of Earth's early atmosphere was different from the one used in their experiment. However, more recent experiments with different mixes of gases have produced similar results.
Explain the endosymbiotic theory
The endosymbiotic theory proposes that prokaryotic cells entered early eukaryotic organisms. Over time a symbiotic relationship evolved between primitive eukaryotic cells and the prokaryotic cells within them.
How did sexual reproduction speed up the evolutionary process
Sexual reproduction shuffles and reshuffles genes in each generation. This increase in
genetic variation greatly increases the chances of evolutionary change due to natural selection
What is the most likely cause of the great amount of diversity currently seen in multicellular life forms
Early multicellular life most likely underwent a series of adaptive radiations.
Once DNA evolved what could have caused it to become the primary means of transmitting genetic information instead of RNA
DNA was a more stable information-storing molecule than RNA.
After Precambrian time, the basic divisions of the geologic time scale from larger to smaller are
eons; era; periods
fossilized evidence of Earth's first forms of life would consits of
prokaryotes from the Precambrain
Palentologists identify a new species of fossil on two different continents; what geological process would most likely responsible for this fossil found in both places
What clade is most likely to survive a series of catastrophic events over
a clade with many distantly related and diverse species
The Australian flying phalanger is a marsupial flying squirrel; Its appearance, behavior, environment, and diet closely resemble those of the American flying squirrel, a placental mammal, This resemblence is most likely due to
A species at equilibrium migrates into a new enviornment and soon begins a period of rapid evoltion. The type of evolution that occurred is most likely ___________-
Fossils of the coelcanth, a primitive fish, date back about 140 million years. Modern coelacanths are virtually identical to their fossil ancestors. This species most likely evolves through the process of ________________ ____________-
Master control genes, or Hox Genes, affect evoltion through.........
small changes during embryological development that lead to different body plans
A plant evolves a high level of poison that enables it to defend itself against insects; Soon an insect that prefers to eat this plant evolves an enzyme that breaks down this poision. This is an example of
our scientific hypothesis about the origin of life holds that
RNA existed before DNA
the endosymbiotic theory proposes that eukaryotic cells arose from.........
communities formed by prokaryotes
Sexual reproduction contributes to genetic diversity by allowing ...........
genes from a 2 parents to be mixed and remixed before being passed to offspring
The fossil record shows.........
that most organisms that ever lived on Earth are extinct
To be useful as an index fossil a species must have existed for a.........
short period of time over a wide geographic range
How would you date a sample of rock that you suspect as being on of the earliest on Earth
use a radioactive isotope with a long half-life
Earth's first atmosphere was composed primarily of carbon dioxide, ____________, and water vapor. An event during which many types of living things suddenly die out is called __________. ___________ may have evolved from photosynthetic prokaryotes that moved into ancient eukaryotic cells.
Why is fossil record an incomplete history of life
Because the formation of any fossil depends upon the precise combination of conditions. For every organism that leaves a fossil, many more die without leaving a trace.
What can you infer about the relative ages of two fairly young fossils if fossil A has a greater amount of carbon-12 compared to carbon-14 than does fossil B
fossil A is older than fossil B. A fossil with a smaller proportion of carbon-14 than another fossil has been in existence longer. Also, you could learn the absolute ages of these fossils
why are the divisions of geologic time Not standard lenghts such as 100 million years
The divisions of geologic time are based on evidence from rock layers that reveal major changes in fossil animals and plants. These divisions vary in length
When they conducted their famous experiments, Stanley Miller and Harold Urey made certain that no microorganisms contaminated their lab equipment. Why might microorganisms have harmed the accuracy of their result
Microorganisms are composed of the very molecules Miller and Urey were trying to produce, so their presence or their waste products might have falsely indicated that organic molecules were produced from the simpler molecules.
What role did microscopes play in the origin of the endosymbiotic theory more than 100 years ago
Scientists could see that the membranes of mitochondria and chloroplasts resembled the plasma membranes of free-living prokaryotes
Gardeners often reproduce favorite plants by planting cuttings from the plant instead of seeds. Is this sexual or asexual reproduction? How would this process affect the genetic diversity of the garden population
This is asexual reproduction because there is a single parent. Using cuttings from a single plant would reduce the genetic diversity of the population.
Explain how living organisms changed the enviornment during Earth's early years
As photosynthetic organisms increased in number, the massive amounts of oxygen these organisms generated caused the dissolved iron in ocean water to settle out. They also pulled large quantities of carbon dioxide out of the atmosphere and replaced it with oxygen. This reduction in carbon dioxide caused Earth to cool.
suppose that a scientist found a fossilized fish on the surface of the ground. Describe a possible set of events that could have taken place first to form the fossil and then to situate it on the ground surface
The fish died and was buried in sediment at the bottom of a body of water. Over time, the weight of upper layers of sediment compressed the lower layers, containing the fish, into new rocks. Minerals replaced parts of the fish's body, producing a fossil. The once-deep sedimentary layer containing the fossil was uplifted by geological forces and then eroded, exposing the fossil
The alga Chlamydomonas normally reproduces asexually. However, it switches to sexual reproduction when there is an unfavorable change in its environment. Would Chlamydomonas evolve more quickly in a favorable environment or an unfavorable environment? Explain your answer.
It would evolve more quickly in an unfavorable environment because sexual reproduction leads to genetic variation. In asexual reproduction the offspring is identical to the parent and can only be genetically different through a mutation. Sexual reproduction means the offspring gets DNA from two parents and then it is shuffled. There is much more genetic variation in organisms that reproduce sexually, meaning the organism will evolve faster.
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