Geology 105: History of Life Midterm 2	April 29, 1998 Version 1
I. Write your name and social security number on your scantron form. II. Write the version number of your exam on the scantron form. III. There are 50 questions on the exam worth one point each. Be sure to read the questions carefully before answering.

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1) The earth and solar system are thought to have formed at different times. A. true B. false   2) Which of the following is probably not an event that occurred on earth between 4.6 and 4.0 billion years ago: A. volcanic activity produces an atmosphere rich in CO2. B. ignition of the sun drives the early atmosphere away. C. the earth melted and differentiated. D. bacterial photosynthesis produced O2. E. continued bombardment of the planet by asteriods.   3) The age of the earth is currently thought to be: A. 3.8 million years B. 543 million years C. 4000 years D. 4.6 billion years E. 3.5 billion years   4) Life is thought to have formed between 4.0 and 3.8 billion years ago. A. true B. false   5) Miller's experiments suggested that some of the building blocks of life: A. were first manufactured in the Cambrian Period. B. could be generated by abiotic processes. C. were related to melting and differentiation of the earth. D. were generated in a glass beaker 3.8 billion years ago. E. were unimportant in the evolution of life.   6) Some of the building blocks of life may have been brought to earth by comets. A. true B. false   7) Which of the following events was probably of prime importance in the origin of life: A. oxygen levels rose to a level where hard parts could form. B. precipitation of iron oxides formed banded-iron formations. C. formation of the oceans. D. mitochondria evolved from bacteria. E. melting and differentiation of the earth.   8) The oldest known fossils are found in: A. 565 million year old sedimentary rocks in Namibia B. 1.6 billion year old sedimentary rocks from the Grand Canyon C. 3.1 billion year old rocks in southern Africa D. 3.5 billion year old sedimentary rocks in northwestern Australia. E. 3.8 billion year old volcanic rocks in Greenland   9) Mound-like structures build by trapping sediment in bacterial mats are called: A. stalactites B. stromatolites C. graptolites D. small shelly fossils E. crinoids   10) Archean microfossils are most commonly preserved in what type of rock: A. granite B. basalt C. sandstone D. gneiss E. chert   11) Banded-iron formations are thought to result from: A. volcanic activity on the early continents. B. increasing levels of oxygen in the atmosphere and oceans. C. Precambrian glaciations. D. the need for steel mills near Detroit E. the formation of uraninite placer deposits.   12) Bacterial photosynthesis was important in the Archean because: A. it reduced levels of oxygen in the early atmosphere. B. it resulted from the evolution of the eukaryotes. C. it produced oxygen. D. it did not provide food for early bacteria. E. it produced amino acids.   13) Why do we think that life was only established once on the earth? A. it is very difficult to produce the building blocks of life B. the history of the earth is too short for life to form more than once. C. oxygen levels in the Cambrian are too low to establish life. D. all life on earth uses the same basic biochemical pathways E. when life arose, the earth was very similar to the way it is now.   14) Eukaryotes probably evolved before 2.5 billion years ago because O2 is not used in eukaryote biochemistry, A. true B. false   15) Which of the following is not a difference between prokaryote and eukaryote cells: A. eukaryotes generally have an expandable cell membrane, prokaryotes do not B. eukaryotes are generally smaller than prokaryotes C. eukaryotes generally have mitochondria, prokaryotes do not. D. eukaryotes may have chloroplasts, prokaryotes do not. E. eukaryotes generally have a nucleus, prokaryotes do not.   16) The evolution of the eukaroyte cells from prokaryote cells: A. is well documented in the fossil record. B. occurred at the base of the Cambrian. C. is inferred from biochemical studies. D. did not occur. E. occurred around 3.8 billion years ago.   17) Mitochondria are important for: A. photosynthesis in prokaryote cells. B. respiration in prokaryote cells. C. photosynthesis in eukaryote cells. D. respiration in eukaryote cells. E. reproduction in prokaryote cells.   18) Mitochodria and chloroplasts have several traits similar to bacteria, suggesting that these organelles evolved from bacteria. A. true B. false   19) Recent discoveries in China indicate that the presence of which metazoan group at 570 million years ago? A. arthropods B. brachiopods C. chordates D. porifera E. echinoderms   20) The Cambrian explosion refers to a 40 million year period when most of the metazoan phyla appear. A. true B. false   21) Which of the following is an important Precambrian soft-bodied fossil locality: A. The Burgess Shale, British Columbia. B. Mazon Creek, Illinois. C. The Merced Formation, California. D. Ediacara hills, Australia. E. The Grand Canyon, Arizona   © University of Adelaide, used with permission of Tate Geological Museum   22) The organism pictured above is a member of the Burgess Shale fauna. A. true B. false   23) The organism pictured above is: A. Swartpuntia B. Hallucigenia C. Mawsonites D. Olenellus E. Dickensonia   24) Excepting possible sponge spicules in the late Precambrian, the first fossils with hard parts appear in the: A. Devonian B. Ordovician C. Silurian D. Cambrian E. Vendian   From: http://www.nmnh.si.edu/paleo/pfoslidx.htm   25) The organism pictured above is: A. Olenellus B. Hallucigenia C. Aysheaia D. Pikaia E. Wiwaxia   26) The organism pictured above is most closely related to which metazoan group: A. crinoids B. ammonites C. trilobites D. corals E. synapsids   27) Which of the following has not been postulated as a cause for the Cambrian explosion A. increased O2 levels B. evolution of vertically burrowing metazoans C. increase in shallow sea environments D. evolution of a large metazoan predator E. extinction of the Ediacaran fauna   28) Which of the following phyla did not first appear during the Cambrian explosion A. cnidarians B. arthropods C. chordates D. porifera E. molluscs   29) Which of the following organisms was the dominant group in the Cambrian oceans A. crinoids B. trilobites C. inarticulate brachiopods D. archeocyathids E. ammonites   30) In the marine biosphere, the Cambrian fauna was displaced in the Ordovician by the Paleozoic fauna consisting of: A. pelycosaurs, therapsids, and rhipidistians. B. trilobites, inarticulate brachiopods, and archeocyathids. C. ammonites, gastropods, and fish. D. crinoids, articulate brachiopods,corals, bryozoans, and nautiloids. E. rhyniophytes, pteridosperms, and progymnosperms.   31) The number of families in the marine biosphere decreased from 400 in the Cambrian to about 200 in the Ordovician and Silurian. A. true B. false   32) The addition of zooplankton and benthic predators to the early Paleozoic trophic structure did not help increase diversity. A. true B. false   33) In the Devonian, fishes radiated into which three groups? A. placoderms, ostrocaderms, and rhipidistians. B. ostracoderms, ammonites, and trilobites. C. placoderms, cartilaginous fishes, and boney fishes. D. nautiloids, ammonites, and gastropods. E. pelycosaurs, therapsids, and diapsids.   34) The ostracoderms were the dominant fish group in the Devonian. A. true B. false   35) The late Devonian rhipidistians are a group of: A. cartilaginous fish covered by boney scales. B. cartilaginous fish that dominated the Devonian oceans. C. ray-fin boney fishes. D. lobe-fine fishes that the modern lungfishes evolved from. E. lobe-fin fishes that the early amphibians evolved from.   36) Which group replaced the early Paleozoic nautiloids as an important benthic predator A. crinoids B. ammonites C. articulate brachiopods D. tabulate corals E. trilobites   37) Which of the following probably lead to the invasion of land by plants A. increased food sources in aquatic environments. B. high levels of herbivory on land. C. high levels of competition for space in aquatic environments. D. decreased light levels on land. E. increased humidity in aquatic environments.   38) Which of the following probably did not result from the invasion of land by plants: A. decreased CO2 levels in the atmosphere. B. opening new environments for animals to invade. C. reduction in the size of coal swamps. D. decreased rates of erosion on land. E. increased rates of deposition in deltaic environments.   39) Arthropods where preadapted for the invasion of land because: A. their exoskeleton provided both support and protection from the moisture loss. B. ostracods were planktonic. C. their legs allowed them to swim in the shallow marine environment. D. they extracted O2 from water through gills. E. trilobites were deposit feeders.   40) To successfully invade land plants and animals had to overcome problems unique to land, including: A. support, reproduction, moisture loss, and gas exchange. B. predation and herbivory. C. gas exchange through gills. D. reduced levels of ultraviolet light. E. anoxic water, increased sedimentation rates, and variable light levels.   41) Xylem is the conductive tissue that allows plants to transmit food from the leaves to the roots. A. true B. false   42) What was the reproductive structure that allowed vertebrates to move away from an aquatic existence: A. legs and feet. B. amniotic egg. C. lungs. D. scales. E. seeds   43) The Carboniferous Period is named for the extensive coal deposits produced by land plants. A. true B. false   44) The pelycosaurs Dimetrodon and Edaphosaurus had sails on their backs that were probably used to: A. hinder movement through dense forests. B. capture prey. C. move across lakes and ponds. D. impress the opposite sex. E. help thermoregulation.   45) Therapsids, the synapsid group that dominated the late Permian, are important in the history of life because: A. they are the first reptiles with amniotic eggs. B. birds evolved from them. C. they had gills as well as lungs D. mammals evolved from them. E. dinosaurs evolved from them.   46) Therapsids' ability to live at high latitudes indicates that they probably did not have internal thermoregulation. A. true B. false   47) Many of the groups that dominated Paleozoic marine fauna did not survive the Permo-Triassic extinctions. A. true B. false   48) The mass extinctions at the end of the Paleozoic were probably caused by A. a single event, like an asteroid impact. B. a series of events that made the environment harsher on life. C. the opening of the Atlantic Ocean. D. volcanic activity in Hawaii. E. decreased erosion rates on land.   49) Land faunas suffered more than marine faunas in the Permo-Triassic extinctions. A. true B. false   50) Jurassic sauropods probably attained their immense size in order to: A. avoid predation by Tyranosaurus. B. impress members of the opposite sex. C. walk across rivers and lakes without getting their heads wet. D. feed on vegetation. E. avoid dusty conditions near the ground.