Biology: Chapter 17 – The History of Life (Review)

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Scientists who study fossils are called
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paleontologists
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What is the fossil record?
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It is information about past life that is based on fossils.
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What evidence does the fossil record provide?
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It provides evidence about the history of life on Earth and how different groups of organisms have changed over time.
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Species that died out are said to be
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extinct
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Is the following sentence true or false? About half of all species that have ever lived on Earth have become extinct.
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false
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Circle the letter of each sentence that is true about fossils. a. Most organisms that die are preserved as fossils. b. Fossils can include footprints, eggs, or other traces of organisms. c. Most fossils form in metamorphic rock. d. The quality of fossil preservation varies.
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b. and d.
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How do fossils form in sedimentary rock?
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Sediments settle to the bottom of lakes and seas and bury dead organisms. The weight of upper layers of sediment compresses lower layers into rock and turns the dead organisms into fossils.
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The two techniques paleontologists use to determine the age of fossils.
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a. Relative dating b. Radioactive dating
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Circle the letter of each sentence that is true about relative dating. a. It determines the age of a fossil by comparing its placement with that of fossils in other layers of rock. b. It uses index fossils. c. It allows paleontologists to estimate a fossil’s age in years. d. It provides no information about absolute age.
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a., b., and d.
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Is the following sentence true or false? Older rock layers are usually closer to Earth’s surface than more recent rock layers.
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false
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Is the following sentence true or false? Scientists use radioactive decay to assign absolute ages to rocks.
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true
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The length of time required for half of the radioactive atoms in a sample to decay is called a(an)
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half-life
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The use of half-lives to determine the age of a sample is called
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radioactive dating
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How do scientists calculate the age of a sample using radioactive dating?
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They measure the amount of remaining radioactive isotopes it contains. The smaller the amount, the older the sample.
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Is the following sentence true or false? All radioactive elements have the same half-life.
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false
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Geologic Time Scale
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Geologic Time Scale
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Circle the letter of the choice that lists the eras of the geologic time scale in order from most recent to oldest. a. Mesozoic, Paleozoic, Cenozoic b. Cenozoic, Paleozoic, Mesozoic c. Cenozoic, Mesozoic, Paleozoic d. Paleozoic, Mesozoic, Cenozoic
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c.
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Circle the letter of each sentence that is true about the geologic time scale. a. The scale is used to represent evolutionary time. b. Major changes in fossil organisms separate segments of geologic time. c. Divisions of the scale cover standard lengths of 100 million years. d. Geologic time begins with the Cambrian Period.
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a. and b.
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The six components of Earth’s early atmosphere.
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a. hydrogen cyanide b. carbon dioxide c. carbon monoxide d. nitrogen e. hydrogen sulfide f. water
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Is the following sentence true or false? Liquid water first occurred on Earth more than 4 billion years ago.
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false
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Miller and Urey’s apparatus simulated lightning storms on early Earth. What part?
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Miller and Urey’s apparatus simulated lightning storms on early Earth.What part?
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Circle the letter of each sentence that is true about Miller and Urey’s experiments. a. Their purpose was to determine how the first organic molecules evolved. b. They led to the formation of several amino acids. c. They accurately simulated conditions in Earth’s early atmosphere. d. The results were never duplicated in experiments by other scientists.
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a. and b.
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What are proteinoid microspheres?
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They are tiny bubbles, formed of large organic molecules, that have some characteristics of living cells.
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Is the following sentence true or false? Scientists know how DNA and RNA evolved.
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false
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Why do scientists think that RNA may have evolved before DNA?
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Experiments show that small sequences of RNA could have formed and replicated on their own in the conditions present on early Earth.
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*Once DNA evolved, why would it have become the primary means of transmitting genetic information?
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It is more stable than RNA.
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Microscopic fossils are called
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microfossils
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Circle the letter of each sentence that is true about the earliest life forms on Earth. a. They resembled modern bacteria. b. They were eukaryotes. c. They relied on oxygen. d. They were not preserved as fossils.
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a.
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How did early photosynthetic bacteria change Earth?
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They produced oxygen, which first removed iron from the oceans and then accumulated in the atmosphere.
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Is the following sentence true or false? The rise of oxygen in the atmosphere drove some life forms to extinction.
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true
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Is the following sentence true or false? The ancestor of all eukaryotic cells evolved about 2 billion years ago.
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true
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What was the first step in the evolution of eukaryotic cells?
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the evolution of internal cell membranes.
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What does the endosymbiotic theory propose?
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It proposes that eukaryotic cells arose from living communities formed by several organisms.
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Circle the letter of each choice that provides support for the endosymbiotic theory. a. The membranes of mitochondria and chloroplasts resemble the plasma membranes of free-living prokaryotes. b. Mitochondria and chloroplasts do not have DNA. c. Mitochondria and chloroplasts have ribosomes that are similar in size and structure to those of bacteria. d. Mitochondria and chloroplasts reproduce by binary fission as bacteria do.
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a., c., and d.
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How did sexual reproduction speed up the evolutionary process?
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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.
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Is the following sentence true or false? Sexual reproduction evolved after the first multicellular organisms appeared.
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false
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Is the following sentence true or false? Almost 90 percent of Earth’s history occurred during the Precambrian.
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true
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Circle the letter of each sentence that is true about life in the Precambrian. a. Anaerobic and photosynthetic forms of life appeared. b. Aerobic forms of life evolved, and eukaryotes appeared. c. Multicellular life forms evolved. d. Life existed on the land and in the sea.
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a., b., and c.
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Why do few fossils exist from the Precambrian?
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The animals were all soft-bodied.
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The first part of the Paleozoic Era is the…
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Cambrian Period
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Is the following sentence true or false? Life was not very diverse during the Cambrian Period.
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false
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Circle the letter of each sentence that is true about the Cambrian Period. a. Organisms with hard parts first appeared. b. Most animal phyla first evolved. c. Many animals lived on the land. d. Brachiopods and trilobites were common.
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a., b., and c.
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What evolutionary events occurred in the Ordovician and Silurian Periods?
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The first vertebrates evolved, and insects first appeared.
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What evolutionary events occurred in the Devonian Period?
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Many groups of fishes were present in the oceans, and the first amphibians evolved.
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What evolutionary events occurred in the Carboniferous and Permian Periods?
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Reptiles evolved from amphibians, and winged insects evolved into many forms.
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Animals first began to invade the land during the…
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Devonian Period.
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Where does the Carboniferous Period get its name?
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Vast swampy forests of giant ferns and other plants that grew during that time formed thick deposits of sediment that changed into coal over millions of years.
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When many types of living things become extinct at the same time, it is called a(an)
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mass extinction
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Is the following sentence true or false? The mass extinction at the end of the Paleozoic affected only land animals.
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false
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What evolutionary event occurred in the Triassic Period in the Mesozoic Era?
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First mammals
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What evolutionary event occurred in the Jurassic Period in the Mesozoic Era?
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First birds
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What evolutionary event occurred in the Cretaceous Period in the Mesozoic Era?
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First flowering plants
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The Mesozoic Era is called the Age of…
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Reptiles
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The first dinosaurs appeared in the…
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Triassic Period
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Is the following sentence true or false? The mammals of the Triassic Period were very small.
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true
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*Is the following sentence true or false? Many paleontologists now think that dinosaurs are close relatives of birds.
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false
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The dominant vertebrates throughout the Cretaceous Period were
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reptiles
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What advantage do flowering plants have over conifers?
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Their seeds are enclosed in a fruit, which protects the seed and aids in dispersing it to new locations.
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Describe the mass extinction that occurred at the end of the Cretaceous Period.
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More than half of all plant and animals groups were wiped out, including all of the dinosaurs.
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Is the following sentence true or false? During the Cenozoic Era, mammals evolved adaptations that allowed them to live on land, in water, and in the air.
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true
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The Cenozoic Era is called the Age of…
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Mammals
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What were Earth’s climates like during the Tertiary Period?
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They were generally warm and mild.
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How did Earth’s climate change during the Quaternary Period?
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First it cooled, causing a series of ice ages. Then it began to warm again.
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Is the following sentence true or false? The very earliest ancestors of our species appeared about 100,000 years ago.
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false
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The large-scale evolutionary changes that take place over long periods of time are referred to as…
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macroevolution
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Topics in Macroevolution include…
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a. Extinction (*mass extinctions) b. Adaptive radiation c. Convergent evolution d. Coevolution e. Punctuated equilibrium f. Changes in developmental genes
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What are possible causes of mass extinctions?
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Possible causes include a huge asteroid striking Earth, many large volcanoes erupting, continents changing position, and sea levels changing.
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What effects have mass extinctions had on the history of life?
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The disappearance of so many species left ecological niches open. Often, the result was a burst of evolution that produced an abundance of new species.
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The process of a single species or a small group of species evolving into several different forms that live in different ways is called…
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adaptive radiation
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What led to the adaptive radiation of mammals?
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The disappearance of the dinosaurs.
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The process by which unrelated organisms come to resemble one another is called…
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convergent evolution
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Circle the letter of each choice that is an example of convergent evolution. a. Bird’s wing and fish’s fin b. Shark’s fin and dolphin’s limb c. Human’s arm and bird’s wing d. Human’s leg and dolphin’s limb
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b.
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The process by which two species evolve in response to changes in each other over time is called…
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coevolution
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How have plants and plant-eating insects coevolved?
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Plants have evolved poisons to prevent insects from feeding on them. Insects, in turn, have evolved ways of inactivating or eliminating the poisons.
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The idea that evolution occurs at a slow, steady rate is called…
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gradualism
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What are some reasons rapid evolution may occur after long periods of equilibrium?
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It may occur when a small population becomes isolated or a small group migrates to a new environment. It may also occur following a mass extinction.
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The pattern of long, stable periods interrupted by brief periods of more rapid change is called…
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punctuated equilibrium
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Is the following sentence true or false? Evolution has often proceeded at different rates for different organisms.
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true
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How can hox genes help reveal how evolution occurred?
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Homologous hox genes establish body plans in animals that have not shared a common ancestor in hundreds of millions of years. In addition, major evolutionary changes may be based on hox genes.
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Is the following sentence true or false? Changes in the timing of genetic control during embryonic development can contribute to the variation involved in natural selection.
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true
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Scientist who studies fossils
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paleontologist
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Term used to refer to a species that has ceased to exist
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extinct
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Process by which a single species evolves into many different forms
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adaptive radiation
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Microscopic fossil
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microfossil
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Unit of time into which eras are subdivided
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period
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Length of time required for half of the radioactive atoms in a sample to decay
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half-life
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Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock
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relative dating
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Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
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punctuated equilibrium
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One of several subdivisions of the time between the Precambrian and the present
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era
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fossils used to compare the relative age of a fossil
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index fossil
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measure evolutionary time
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geologic time scale
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time span shorter than an era
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period
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span of geological time that is subdivided into periods
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era
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tiny bubbles formed by large organic molecules
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microsphere
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Scientists who specialize in the study of fossils are called…
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paleontologists
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Sedimentary rocks form when layers of small particles compressed….
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under water
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Radioactive dating of rock samples…
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is a method of absolute dating
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Half-life is the length of time required for half the atoms in a radioactive sample to…
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decay
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Earth’s first atmosphere contained little or no….
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oxygen
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In Miller and Urey’s experiments with the origin of life forms, electric sparks were passed through a mixture of gases to…
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simulate lightning
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Outlines of ancient cells that are preserved well enough to identify them as prokaryotes are…
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microfossils
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What event occurred at the end of the Paleozoic Era?
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mass extinction
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The process that produces a similar appearance among unrelated groups of organisms is…
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convergent evolution
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As a group, the large-scale evolutionary changes that take a place over long periods of time are called…
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macroevolution
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How does relative dating enable paleontologists to estimate a fossil’s age?
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It allows paleontologists to estimate a fossils age by comparing it to other nearby fossils or rock layers whose ages are known.
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Explain how radioactivity is used to date rocks.
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It allows scientists to determine the absolute age of fossils by determining how much of certain radioactive substances have decayed and how long it would have taken for that amount of decay to occur.
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What is the geologic time scale? How was it developed?
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It is a timeline that divides Earth’s history into several major time periods, called eras, then subdivides the eras into shorter periods of time, called periods. These time periods are not made up of uniform lengths of time, such as 10 million or 50 million years each, because they were created before radioactive dating existed so there was no way to tell how old rocks and fossils that were from each period or era were.
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Discuss what scientists hypothesize about Earth’s early atmosphere and the way oceans formed.
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*When Earth was young, a collision with a very large object produced enough heat to melt Earth. Elements then rearranged themselves by density. The least dense elements, including hydrogen and nitrogen, formed the first atmosphere. About 3.8 billion years ago, Earth cooled enough for water to remain a liquid. Thunderstorms drenched the planet, eventually forming the oceans.
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How are protenoid microspheres like living cells?
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1) They have selectively porous membranes which can let water molecules pass through them. 2) They can store energy as well as release energy.
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How did the addition of oxygen to Earth’s atmosphere affect the evolution of life?
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Some organisms began to evolve more efficient metabolic pathways that used oxygen for respiration; others became restricted to oxygen-free habitats.
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Describe the endosymbiotic theory.
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The endosymbiotic theory states that the first eukaryotic cells were formed from symbiosis among different prokaryotic cells. One type with the ability to use oxygen to generate ATP evolved into mitochondria. Another type that carried out photosynthesis evolved into chloroplasts. Both types were engulfed by other cells.
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Describe life as it existed in Precambrian Time.
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The first organisms were anaerobic, heterotrophic bacteria. Photosynthetic bacteria followed, adding oxygen to the atmosphere. Some bacteria adapted to the presence of oxygen, using it in cell respiration. The next to appear were eukaryotes, which gave rise to multicellular organisms.
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During what era did marine life become diverse?
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The Paleozoic Era
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What significant mammalian adaptations led to their success during the Cenozoic Era?
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Mammalian adaptations included hair that provided insulation against the cold and the protection of young before and after birth.
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What events led to the diversification of mammals?
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Disappearance of the dinosaurs enabled the smaller, relatively scarce mammals to flourish and diversify.
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Explain the process of adaptive radiation. Give an example.
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In adaptive radiation, species evolve into several different forms that live in different ways. Examples: dinosaurs, mammals.
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Explain the pattern known as punctuated equilibrium.
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Punctuated equilibrium is a pattern in which long periods of little or no evolutionary change are interrupted by brief periods of rapid change.
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Use an example to explain the concept of coevolution.
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When a small group of life forms transfers to a new place because species can evolve faster to adapt to their new environment to find their own place.
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How can hox genes provide evidence of evolution?
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Homologous hox genes established body plans in organisms that had not shared common ancestors for millions of years.
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The half-life of carbon-14 is 5770 years. What fraction of carbon-14 in the fossil of an organism that died 23,080 years ago? Explain your answer. (Know carbon-14 dating for test)
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23,080 will cover four half-lives of carbon-14. After four half-lives only 1/16 of the original amount of carbon-14 will remain.

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