Presentation on theme: "Chapter 14 The History of Life"— Presentation transcript:
1Chapter 14 The History of Life Section 1: Fossil Evidence of ChangeSection 2: The Origin of Life
2Earth formed about 4.6 billion years ago. Chapter 14The History of Life14.1 Fossil Evidence of ChangeLand EnvironmentsEarth formed about 4.6 billion years ago.Gravity pulled the densest elements to the center of the planet.After about 500 million years, a solid crust formed on the surface.
314.1 Fossil Evidence of Change Chapter 14The History of Life14.1 Fossil Evidence of ChangeAtmosphereThe gases that likely made up the atmosphere are those that were expelled by volcanoes.Water vapor (H2O)Carbon dioxide (CO2)Sulfur dioxide (SO2)Carbon monoxide (CO)Hydrogen sulfide (H2S)Hydrogen cyanide (HCN)Nitrogen (N2)Hydrogen (H2)
4A fossil is any preserved evidence of an organism. Chapter 14The History of Life14.1 Fossil Evidence of ChangeClues in RocksA fossil is any preserved evidence of an organism.Most organisms decompose before they have a chance to become fossilized.
514.1 Fossil Evidence of Change Chapter 14The History of Life14.1 Fossil Evidence of Change
6Nearly all fossils are formed in sedimentary rock. Chapter 14The History of Life14.1 Fossil Evidence of ChangeFossil FormationNearly all fossils are formed in sedimentary rock.The sediments build up until they cover the organism’s remains.Minerals replace the organic matter or fill the empty pore spaces of the organism.
7Chapter 14The History of Life14.1 Fossil Evidence of ChangeDating fossilsRelative dating is a method used to determine the age of rocks by comparing them with those in other layers.
8Uses the decay of radioactive isotopes to measure the age of a rock Chapter 14The History of Life14.1 Fossil Evidence of ChangeRadiometric DatingUses the decay of radioactive isotopes to measure the age of a rockRadioactive isotopes that can beused for radiometric dating are found only inigneous or metamorphic rocks.
9The Geologic Time Scale Chapter 14The History of Life14.1 Fossil Evidence of ChangeThe Geologic Time ScaleThe geological time scale is a model that expresses the major geological and biological events in Earth’s history.Divided into 4 eras: the Precambrian era, thePaleozoic era, the Mesozoic era, and theCenozoic eraEach era is divided into PERIODSEach era is divided into one or more periods.
10Autotrophic prokaryotes enriched the atmosphere with oxygen. Chapter 14The History of Life14.1 Fossil Evidence of ChangePrecambrianNearly 90 percent of Earth’s entire history, stretching from the formation of Earth to the beginning of the Paleozoic era about 542 million years agoAutotrophic prokaryotes enriched the atmosphere with oxygen.By the end of this era (~ 544 mya) multicellular eukaryotes, such as sponges and jellyfish filled the oceans
11The first tetrapods emerged in the Devonian. Chapter 14The History of LifeThe Paleozoic EraThe ancestors of most major animal groups diversified in what scientists call the Cambrian explosion.Life in the oceans continued to evolve at the end of the Cambrian period.Fish, land plants, and insects appeared during the Ordovician and Silurian periods.The first tetrapods emerged in the Devonian.
12About 90% of marine species and 70% of land species disappeared Chapter 14The History of Life14.1 Fossil Evidence of ChangeThe largest mass extinction ended the Paleozoic era at the end of the Permian period.About 90% of marine species and 70% of land species disappearedBetween 60 and 75 percent of the speciesalive went extinct.
13About 65 million years ago, a meteorite struck Earth. Chapter 14The History of Life14.1 Fossil Evidence of ChangeThe Mesozoic EraMammals and dinosaurs first appeared late in the Triassic period, and flowering plants evolved from nonflowering plants.The middle of this era is called the Jurassic period (~208 mya) which is referred to as the Age of the DinosaursBirds evolved from a group of predatory dinosaurs in the middle of the Jurassic period.About 65 million years ago, a meteorite struck Earth.
14Chapter 14The History of Life14.1 Fossil Evidence of ChangePlate tectonics describes the movement of several large plates that make up the surface of Earth.These plates, some of which contain continents, move atop a partially molten layer of rock underneath them.
15Mammals became the dominant land animals. Chapter 14The History of Life14.1 Fossil Evidence of ChangeThe Cenozoic EraMammals became the dominant land animals.After the mass extinction at the end of the Mesozoic era, mammals of all kinds began to diversify.The modern human species appeared perhaps as recently as 200,000 years ago
16Life requires proteins. Chapter 14The History of Life14.2 The Origin of LifeMaking ProteinsLife requires proteins.One possible mechanism for the formation of proteins would be if amino acids were bound to a clay particle.
17Some RNA sequences appear to have changed very little through time. Chapter 14The History of Life14.2 The Origin of LifeGenetic CodeSome RNA sequences appear to have changed very little through time.Many biologists consider RNA to have been life’s first coding system.Other researchers have proposed that clay crystals could have provided an initial template for RNA replication.
18Scientists hypothesize that the first cells were prokaryotes. Chapter 14The History of Life14.2 The Origin of LifeCellular EvolutionScientists hypothesize that the first cells were prokaryotes.Many scientists think that modern prokaryotes called archaea are the closest relatives of Earth’s first cells.
19Photosynthesizing Prokaryotes Chapter 14The History of Life14.2 The Origin of LifePhotosynthesizing ProkaryotesArchaea are autotrophic.They do not obtain their energy from the Sun.Archaea also do not need or produce oxygen.
20Chapter 14The History of Life14.2 The Origin of LifeMany scientists think that photosynthesizing prokaryotes evolved not long after the archaea.Prokaryotes, called cyanobacteria, have been found in rocks as old as 3.5 billion years.
21Chapter 14The History of Life14.2 The Origin of Life
22Which is an example of the theory of spontaneous generation? Chapter 14The History of LifeChapter Diagnostic QuestionsWhich is an example of the theory ofspontaneous generation?Tadpoles become frogs.A starfish can grow from a severed arm.Damp hay and corn create mice.From a tiny acorn, an oak can grow.ABCDCDQ 1
23What gas do scientists think was absent from Earth’s early atmosphere? Chapter 14The History of LifeChapter Diagnostic QuestionsWhat gas do scientists think was absent fromEarth’s early atmosphere?sulfurnitrogenoxygenwater vaporABCDCDQ 2
24In which period did the first land vertebrates appear? Chapter 14The History of LifeChapter Diagnostic QuestionsIn which period did the first land vertebratesappear?CambrianDevonianTriassicMesozoicABCDCDQ 3
25In which type of rock do paleontologists search for fossils? Chapter 14The History of Life14.1 Formative QuestionsIn which type of rock do paleontologists searchfor fossils?igneousmetamorphicsedimentaryvolcanicABCDFQ 1
26Which dating method determines the age of Chapter 14The History of Life14.1 Formative QuestionsWhich dating method determines the age ofrocks by comparing them to rocks in otherlayers?absolute datinggeological datingrelative datingsedimentary datingABCDFQ 2
27Which geological change during the Mesozoic Chapter 14The History of Life14.1 Formative QuestionsWhich geological change during the Mesozoicera had the greatest effect in shaping thecourse of evolution?plate tectonicsextensive glaciationincreased volcanic activitymeteorite impactABCDFQ 3
28At one time people believed that mold growing Chapter 14The History of Life14.2 Formative QuestionsAt one time people believed that mold growingon a piece of cheese was created by thecheese. This is the idea of __________.biogenesistransgenesisprimordial generationspontaneous generationABCDFQ 4
29Which is the half-life of the radioactive isotope shown in the graph? Chapter 14The History of LifeChapter Assessment QuestionsWhich is the half-life of the radioactive isotope shown in the graph?18 years36 years54 years72 yearsABCDCAQ 1
30Which factor made it unlikely that life existed on Chapter 14The History of LifeStandardized Test PracticeWhich factor made it unlikely that life existed onEarth 4 billion years ago?absence of oxygenabsence of foodintense heatintense sunlightABCDSTP 1
31Chapter 14The History of LifeStandardized Test PracticeWhy do scientists believe that archea are the closest relatives to Earth’s first cells?They are eukaryotes.They contain DNA.They carry out photosynthesis.They live in extreme environments.ABCDSTP 6
32Section 1 Vocabulary fossil paleontologist relative dating half-life Chapter 14The History of LifeVocabularySection 1fossilpaleontologistrelative datinghalf-lifegeologic time scaleeraperiodCambrian explosionplate tectonics
33Section 2 Vocabulary spontaneous generation Chapter 14 The History of LifeVocabularySection 2spontaneous generation