Ch. 14 The History of Life Biology Mr. Jones

History of the Earth Formed 4.6 billion year ago Started as hot ball of rock Earth cooled 4.4 bya First life began between 3.9 and 3.4 bya

Fossils Evidence of an organism that lived long ago Evidence of an organism that lived long ago Paleontologists Paleontologists Study ancient lifeStudy ancient life Uses fossils to:Uses fossils to: understand events that happened long ago understand events that happened long ago Determine the kinds of organisms that lived during the past and their behaviors Determine the kinds of organisms that lived during the past and their behaviors Study ancient climate and geography Study ancient climate and geography

How fossils form 1. Organisms are buried in mud, sand, or clay 2. Sediments cover the organism, slows decomposition 3. Minerals from sediments seep into body 4. Over time, sedimentary layers compressed into rock 5. Mineral replace the body’s bone material 6. Earth’s movement or erosion expose the body 7. Rocks form at relatively low temperatures and pressure Prevent damage of organismPrevent damage of organism

Types of Fossils Trace fossils Trace fossils An indirect evidence left by an animalAn indirect evidence left by an animal Include a footprint, a trail, or a burrowInclude a footprint, a trail, or a burrow

Casts Casts A replica or castA replica or cast Minerals in rocks fill a space left by a decayed organismMinerals in rocks fill a space left by a decayed organism

Molds Molds An empty space left by an organisms after it decaysAn empty space left by an organisms after it decays

Petrified Petrified Minerals penetrate and replace the hard parts of an organism Permineralized Permineralized Void spaces in original organism is filled by minerals Petrified Permineralized

Original Remains Amber-preserved or frozen Amber-preserved or frozen An entire organism quickly trapped in ice or tree sap and hardensAn entire organism quickly trapped in ice or tree sap and hardens Amber preserved Frozen

Dating fossils Relative dating Relative dating uses the position of fossils in sediment layers oldest fossil at the bottom layer, youngest on top Can only determine whether one fossil is older than another Cannot determine the actual age Principles of Superposition & Uniformitarianism

Absolute Dating Radiometric dating Radiometric dating use radioactive isotopes (atoms with unstable nuclei that break down or decay) decay of each radioactive element is known and continues at a steady rate

Absolute Dating Half-life the time it takes a radioactive element to get to half its original amount Potassium billion yrs Carbon years

Geologic Time Scale a type of calendar based on the different types of living organisms that have appeared on Earth

Precambrian Era Starts 4.7 bya Starts 4.7 bya Accounts for 87% of Earth’s history Accounts for 87% of Earth’s history Oldest rock dates 3.4 bya Oldest rock dates 3.4 bya Unicellular prokaryotes appeared Unicellular prokaryotes appeared Eukaryotes appeared 2.1 bya Eukaryotes appeared 2.1 bya Ended 345 mya Ended 345 mya Oldest rock from Yukon, 4 byo

Paleozoic Era 345 to 248 mya 345 to 248 mya Appearance of plants and animals including fishes, reptiles, amphibians and ferns Appearance of plants and animals including fishes, reptiles, amphibians and ferns 90% of Earth’s marine species and 70% of land species disappeared 90% of Earth’s marine species and 70% of land species disappeared

Mesozoic Era 248 to 65 mya 248 to 65 mya TriassicTriassic Oldest Oldest Mammals appeared Mammals appeared Dinosaurs first appeared Dinosaurs first appeared JurassicJurassic Age of dinosaurs Age of dinosaurs CretaceousCretaceous Mammals and flowering plants Mammals and flowering plants Dinosaurs and 2/3 of living species became extinct Dinosaurs and 2/3 of living species became extinct

Theory of Continental Drift Continents were joined in a landmass known as Pangaea Continents were joined in a landmass known as Pangaea Pangaea broke apart resulting in two large masses Pangaea broke apart resulting in two large masses At the end of the Mesozoic, most of the continents had taken on their modern shapes At the end of the Mesozoic, most of the continents had taken on their modern shapes Explained by plate tectonics Explained by plate tectonics Movement of the continentsMovement of the continents

The Origin of Life

The Early Ideas Spontaneous generation Spontaneous generation Nonliving material can produce lifeNonliving material can produce life Experiments to disprove this theory Experiments to disprove this theory Francesco RediFrancesco Redi Used maggots in covered and uncovered jars Used maggots in covered and uncovered jars Louis PasteurLouis Pasteur Used curved flasks with heated broth Used curved flasks with heated broth

Francesco Redi 1668 Showed that rotting meat kept away from flies would not produce new flies Maggots appeared only on meat that had been exposed to flies Eggs laid on meat

Louis Pasteur Mid- 1800s Mid- 1800s Used curve-necked flasks Used curve-necked flasks Microorganisms were prevented from entering the flask Microorganisms were prevented from entering the flask When curved necks were broken, broth became cloudy with microorganims When curved necks were broken, broth became cloudy with microorganims

Biogenesis All living things come from other living things All living things come from other living things Became cornerstone of biology after Pasteur’s experiment Became cornerstone of biology after Pasteur’s experiment

The Modern Ideas Alexander Oparin Alexander Oparin Life began in the oceans that formed on early EarthLife began in the oceans that formed on early Earth Energy from sun + lightning+ Earth’s heat = simple compounds (eg. amino acids)Energy from sun + lightning+ Earth’s heat = simple compounds (eg. amino acids) Earth cooled, water vapor condensed to form lakes and seas, compounds collected in the waterEarth cooled, water vapor condensed to form lakes and seas, compounds collected in the water

Stanley Miller and Harold Urey Stanley Miller and Harold Urey Used Oparin’s hypothesis to setup experiment Used Oparin’s hypothesis to setup experiment Produced amino acids and other organic compounds Produced amino acids and other organic compounds

Formation of Protocells Sidney Fox Sidney Fox Produced protocells Produced protocells Large, ordered structure, enclosed by a membraneLarge, ordered structure, enclosed by a membrane Carries out some life activities (growth and division)Carries out some life activities (growth and division) Heated amino acids Heated amino acids

The First True Cells Prokaryotes evolved from a protocell Prokaryotes evolved from a protocell HeterotrophsHeterotrophs AnaerobicAnaerobic Archaebacteria Archaebacteria ProkaryoticProkaryotic AutotrophsAutotrophs Made glucose by chemosynthesis Made glucose by chemosynthesis Lived in harsh environmentsLived in harsh environments Deep-sea vents and hot springsDeep-sea vents and hot springs

Photosynthesizing prokaryotes Photosynthesizing prokaryotes Increased oxygen in atmosphereIncreased oxygen in atmosphere Eukaryotes evolved from prokaryotes Eukaryotes evolved from prokaryotes

Endosymbiont Theory Eukaryote provided beneficial environment Eukaryote provided beneficial environment Prokaryote provided method of energy synthesis Prokaryote provided method of energy synthesis Endosymbiotic, aerobic prokaryotes evolved into modern mitochondria Endosymbiotic, aerobic prokaryotes evolved into modern mitochondria Photosynthetic cyanobacteria evolved into chloroplasts Photosynthetic cyanobacteria evolved into chloroplasts