Chapter 19: The History of Life Section: 19.1 The Fossil Record

Transcription

1 Chapter 19: The History of Life Section: 19.1 The Fossil Record 1 of 40

2 17-1 The Fossil Record Fossils and Ancient Life What is the fossil record? 2 of 40

3 17-1 The Fossil Record Fossils and Ancient Life The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time. 3 of 40

4 17-1 The Fossil Record Fossils and Ancient Life The fossil record provides incomplete information about the history of life. Over 99% of all species that have lived on Earth have become extinct, which means that the species has died out. Those species that still exist are referred to as being extant. 4 of 40

5 17-1 The Fossil Record How Fossils Form How Fossils Form Most fossils form in sedimentary rock. Sedimentary rock forms when exposure to the elements breaks down existing rock into small particles of sand, silt, and clay. 5 of 40

6 17-1 The Fossil Record How Fossils Form Fossil Formation Water carries small rock particles to lakes and seas. 6 of 40

7 17-1 The Fossil Record How Fossils Form Dead organisms are buried by layers of sediment, which forms new rock. 7 of 40

8 17-1 The Fossil Record How Fossils Form The preserved remains may be later discovered and studied. 8 of 40

9 17-1 The Fossil Record Interpreting Fossil Evidence Interpreting Fossil Evidence Paleontologists determine the age of fossils using relative dating or radioactive dating. 9 of 40

10 17-1 The Fossil Record Interpreting Fossil Evidence Relative Dating In relative dating, the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock. Rock layers form in order by age the oldest on the bottom, with more recent layers on top. 10 of 40

11 17-1 The Fossil Record Interpreting Fossil Evidence Relative Dating 11 of 40

12 17-1 The Fossil Record Interpreting Fossil Evidence Index fossils are used to compare the relative ages of fossils. An index fossil is a species that is recognizable and that existed for a short period but had a wide geographic range. 12 of 40

13 17-1 The Fossil Record Interpreting Fossil Evidence Radioactive Dating Scientists use radioactive decay to assign an absolute age to rocks. Radioactive dating is the use of half-lives to determine the age of a sample. A half-life is the length of time required for half of the radioactive atoms in a sample to decay. 13 of 40

14 17-1 The Fossil Record Interpreting Fossil Evidence 14 of 40

15 17-1 The Fossil Record Geologic Time Scale The basic divisions of the geologic time scale are eras and periods. 15 of 40

16 17-1 The Fossil Record 16 of 40

17 17-1 The Fossil Record Extinction Rate Millions of years ago , Extinction rate Permian mass extinction Number of taxonomic families 2,000 1, Cretaceous mass extinction 1, Proterozoic eon Cambrian Ordovician Silurian Devonian Paleozoic Carboniferous Permian Triassic Jurassic Mesozoic Cretaceous Paleogene Ceno- zoic 0 Neogene 17 of 40

18 17-1 The Fossil Record Geologic Time Scale Geologic time begins with Precambrian Time, which covers about 88% of Earth s history. Vendian of 40

19 17-1 The Fossil Record Geologic Time Scale Eras Geologists divide the time between Precambrian time and the present into three eras: Paleozoic Era Mesozoic Era Cenozoic Era 19 of 40

20 17-1 The Fossil Record Geologic Time Scale Permian Carboniferous Devonian Silurian Ordovician Cambrian of 40

21 17-1 The Fossil Record Geologic Time Scale Cretaceous Jurassic Triassic of 40

22 17-1 The Fossil Record Geologic Time Scale 22 of 40

23 17-1 The Fossil Record Geologic Time Scale Clock Model of Earth s History Radiation of mammals First humans First land plants First prokaryotes First multicellular organisms Cenozoic Era Mesozoic Era Paleozoic Era Precambrian Time First eukaryotes Accumulation of atmospheric oxygen 23 of 40

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25 17-1 Which of the following statements about fossils is NOT true? a. Most fossils form in sedimentary rock. b. Fossils occur in a particular order. c. Only a small portion of fossils are from extinct organisms. d. Fossils can be used in relative dating of rock formations. 25 of 40

26 17-1 The fossil record consistently shows evidence that a. all forms of life have existed in all geologic eras. b. living organisms have only been on Earth for a short time. c. living things have changed over time. d. ancient life-forms are much the same as forms found living today. 26 of 40

27 17-1 Index fossils assist paleontologists in dating rocks because they represent species that a. were widely distributed and existed for a very long time. b. existed in a single location for a short period of time. c. were widely distributed and existed for a short time. d. existed in a single location for a very long time. 27 of 40

28 17-1 Determining the age of a fossil by comparing its placement with fossils in other layers of rock is called a. carbon-14 dating. b. fossil-indexing. c. relative dating. d. absolute dating. 28 of 40

29 17-1 According to the geologic time scale, geologic time begins with a. Precambrian Time. b. the Paleozoic Era. c. the Quaternary Period. d. the Cambrian Era. 29 of 40

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31 Chapter 19: The History of Life Section: 19.3 Earth's Early History 31 of 36

32 17-2 Earth's Early History Formation of Earth Formation of Earth Hypotheses about Earth s early history are based on a relatively small amount of evidence. Gaps and uncertainties make it likely that scientific ideas about the origin of life will change. 32 of 36

33 17-2 Earth's Early History Formation of Earth Evidence shows that Earth was not born in a single event. Pieces of cosmic debris were probably attracted to one another over the course of 100 million years. While Earth was young, it was struck by one or more objects, producing enough heat to melt the entire globe. 33 of 36

34 17-2 Earth's Early History Formation of Earth Once Earth melted, its elements rearranged themselves according to density. The most dense elements formed the planet s core. Moderately dense elements floated to the surface, cooled, and formed a solid crust. The least dense elements formed the first atmosphere. 34 of 36

35 17-2 Earth's Early History Formation of Earth What substances made up Earth's early atmosphere? 35 of 36

36 17-2 Earth's Early History Formation of Earth Earth's early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water. 36 of 36

37 17-2 Earth's Early History Formation of Earth Scientists infer that about four billion years ago, Earth cooled and solid rocks formed on its surface. Millions of years later, volcanic activity shook Earth s crust. About 3.8 billion years ago, Earth s surface cooled enough for water to remain a liquid, and oceans covered much of the surface. 37 of 36

38 17-2 Earth's Early History The First Organic Molecules The First Organic Molecules Could organic molecules have evolved under conditions on early Earth? In the 1950s, Stanley Miller and Harold Urey tried to answer that question by simulating conditions on the early Earth in a laboratory setting. 38 of 36

39 17-2 Earth's Early History The First Organic Molecules What did Miller and Urey's experiments show? 39 of 36

40 17-2 Earth's Early History The First Organic Molecules Miller and Urey s Experiment Mixture of gases simulating atmosphere of early Earth Spark simulating lightning storms Water vapor Cold water cools chamber, causing droplets to form. Condensation chamber Liquid containing amino acids and other organic compounds 40 of 36

41 17-2 Earth's Early History The First Organic Molecules Miller and Urey's experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth. Although their simulations of early Earth were not accurate, experiments with current knowledge yielded similar results. 41 of 36

42 17-2 Earth's Early History The Puzzle of Life's Origin The Puzzle of Life's Origin Evidence suggests that million years after Earth had liquid water, cells similar to modern bacteria were common. 42 of 36

43 17-2 Earth's Early History The Puzzle of Life's Origin Formation of Microspheres In certain conditions, large organic molecules form tiny bubbles called proteinoid microspheres. Microspheres are not cells, but they have selectively permeable membranes and can store and release energy. 43 of 36

44 17-2 Earth's Early History The Puzzle of Life's Origin Hypotheses suggest that structures similar to microspheres might have acquired more characteristics of living cells. 44 of 36

45 17-2 Earth's Early History The Puzzle of Life's Origin Evolution of RNA and DNA How could DNA and RNA have evolved? Several hypotheses suggest: Some RNA sequences can help DNA replicate under the right conditions. Some RNA molecules can even grow and duplicate themselves suggesting RNA might have existed before DNA. 45 of 36

46 17-2 Earth's Early History The Puzzle of Life's Origin RNA and the Origin of Life Proteins build cell structures and catalyze chemical reactions RNA nucleotides Abiotic stew of inorganic matter Simple organic molecules RNA helps in protein synthesis RNA able to replicate itself, synthesize proteins, and function in information storage DNA functions in information storage and retrieval 46 of 36

47 17-2 Earth's Early History Free Oxygen Free Oxygen Microscopic fossils, or microfossils, of unicellular prokaryotic organisms resembling modern bacteria have been found in rocks over 3.5 billion years old. These first life-forms evolved without oxygen. 47 of 36

48 17-2 Earth's Early History Free Oxygen About 2.2 billion years ago, photosynthetic bacteria began to pump oxygen into the oceans. Next, oxygen gas accumulated in the atmosphere. 48 of 36

49 17-2 Earth's Early History Free Oxygen What occurred when oxygen was added to Earth's atmosphere? 49 of 36

50 17-2 Earth's Early History Free Oxygen The rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration. 50 of 36

51 17-2 Earth's Early History Origin of Eukaryotic Cells What hypothesis explains the origin of eukaryotic cells? 51 of 36

52 17-2 Earth's Early History Origin of Eukaryotic Cells The Endosymbiotic Theory The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms. 52 of 36

53 17-2 Earth's Early History Origin of Eukaryotic Cells Endosymbiotic Theory Aerobic bacteria Ancient Prokaryotes Nuclear envelope evolving Photosynthetic bacteria Mitochondrion Chloroplast Plants and plantlike protists Ancient Anaerobic Prokaryote Primitive Aerobic Eukaryote Primitive Photosynthetic Eukaryote Animals, fungi, and non-plantlike protists 53 of 36

54 17-2 Earth's Early History Origin of Eukaryotic Cells About 2 billion years ago, prokaryotic cells began evolving internal cell membranes. The result was the ancestor of all eukaryotic cells. According to the endosymbiotic theory, eukaryotic cells formed from a symbiosis among several different prokaryotes. 54 of 36

55 17-2 Earth's Early History Origin of Eukaryotic Cells Aerobic bacteria Ancient Prokaryotes Nuclear envelope evolving Ancient Anaerobic Prokaryote 55 of 36

56 17-2 Earth's Early History Origin of Eukaryotic Cells Prokaryotes that use oxygen to generate energyrich molecules of ATP evolved into mitochondria. Mitochondrion Primitive Aerobic Eukaryote 56 of 36

57 17-2 Earth's Early History Origin of Eukaryotic Cells Prokaryotes that carried out photosynthesis evolved into chloroplasts. Chloroplast Photosynthetic bacteria Primitive Photosynthetic Eukaryote 57 of 36

58 17-2 Earth's Early History Sexual Reproduction and Multicellularity Sexual Reproduction and Multicellularity Most prokaryotes reproduce asexually. Asexual reproduction: yields daughter cells that are exact copies of the parent cell. restricts genetic variation to mutations in DNA. 58 of 36

59 17-2 Earth's Early History Sexual Reproduction and Multicellularity Sexual reproduction shuffles genes in each generation. In sexual reproduction: offspring never resemble parents exactly there is an increased probability that favorable combinations will be produced there is an increased chance of evolutionary change due to natural selection 59 of 36

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61 17-2 Which of the following gases was probably NOT present in the early Earth s atmosphere? a. hydrogen cyanide b. oxygen c. nitrogen d. carbon monoxide 61 of 36

62 17-2 Miller and Urey's experiment was a simulation of Earth's early a. volcanic activity. b. formation. c. atmosphere. d. life. 62 of 36

63 17-2 Proteinoid microspheres are different from cells because microspheres a. have selectively permeable membranes. b. do not have DNA or RNA. c. have a simple means of storing and releasing energy. d. separate their internal environment from the external environment. 63 of 36

64 17-2 The hypothesis that RNA sequences appeared before DNA sequences a. has some evidence in its favor but is still being tested. b. has been rejected since DNA is required to make RNA. c. has been proven since RNA has been made in laboratories. d. has been rejected because it is illogical. 64 of 36

65 17-2 As concentrations of oxygen rose in the ancient atmosphere of Earth, organisms began to evolve a. anaerobic pathways. b. plasma membranes. c. metabolic pathways that used oxygen. d. photosynthesis. 65 of 36

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67 Chapter 19: The History of Life Section: 19.2 Patterns & Processes of Evolution Macroevolution refers to large-scale evolutionary patterns and processes that occur over long periods of time. 67 of 25

68 17-4 Patterns of Evolution Macroevolution Six important topics in macroevolution are: 1. extinction 2. adaptive radiation 3. convergent evolution 4. coevolution 5. punctuated equilibrium 6. changes in developmental genes 68 of 25

69 17-4 Patterns of Evolution Extinction 1. Extinction More than 99% of all species that have ever lived are now extinct. 69 of 25

70 17-4 Patterns of Evolution Extinction What effects have mass extinctions had on the history of life? Mass extinctions have: provided ecological opportunities for organisms that survived resulted in bursts of evolution that produced many new species 70 of 25

71 17-4 Patterns of Evolution Adaptive Radiation 2. Adaptive Radiation Adaptive radiation is the process by which a single species or a small group of species evolves into several different forms that live in different ways. For example, in the adaptive radiation of Darwin's finches, more than a dozen species evolved from a single species. 71 of 25

72 17-4 Patterns of Evolution 72 of 25

73 17-4 Patterns of Evolution Adaptive Radiation Adaptive Radiation of Mammals Artiodactyls Cetaceans Perissodactyls Tubulidentates Hyracoids SireniansProboscideans Ancestral Mammals 73 of 25

74 17-4 Patterns of Evolution Adaptive Radiation 74 of 25

75 17-4 Patterns of Evolution Convergent Evolution Convergent Evolution Different organisms undergo adaptive radiation in different places or at different times but in similar environments. The process by which unrelated organisms come to resemble one another is called convergent evolution. Results in analogous structures. 75 of 25

76 17-4 Patterns of Evolution Coevolution Coevolution Sometimes organisms that are closely connected to one another by ecological interactions evolve together. The process by which two species evolve in response to changes in each other over time is called coevolution. 76 of 25

77 17-4 Patterns of Evolution Punctuated Equilibrium Punctuated Equilibrium Darwin felt that biological change was slow and steady, an idea known as gradualism. 77 of 25

78 17-4 Patterns of Evolution Punctuated Equilibrium Punctuated equilibrium is a pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change. 78 of 25

79 17-4 Patterns of Evolution Developmental Genes and Body Plans Developmental Genes and Body Plans Hox Genes are the master control genes of body layout. Evolution of Wings in Insects 79 of 25

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81 17-4 Darwin's species of finches were very similar but different in beak size and feeding habits. This is an example of a. convergent evolution. b. coevolution. c. adaptive radiation. d. stabilizing selection. 81 of 25

82 17-4 A slow steady change in a particular line of descent is called a. coevolution. b. gradualism. c. punctuated equilibrium. d. convergent evolution. 82 of 25

83 17-4 Master control genes are called a. hox genes. b. developmental genes. c. embryonic genes. d. regulatory genes. 83 of 25

84 17-4 Some evidence suggests that species do not change much over long periods of time and then undergo relatively short periods of rapid speciation. This kind of change is called a. coevolution. b. genetic equilibrium. c. adaptive radiation. d. punctuated equilibrium. 84 of 25

85 17-4 Fossil evidence shows that mass extinctions a. ended the existence of many species in a short period of time. b. occurred mainly when the dinosaurs disappeared. c. require an asteroid strike to occur. d. caused convergent evolution among animals. 85 of 25

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