Ch. 14 – The History of Life Section 1: Fossil Evidence of Change - Early History of the Earth o What was early Earth like? speculation _______________________ – energy from colliding meteorites heated surface, while compression of minerals and decay of radioactive materials heated interior Gases from ___________________ helped form early atmosphere (_________________ __________________________________________) 4.4 billion years ago – Earth cooled enough for atmosphere to condense – led to millions of years of ______________________________________________________________ 3.9-3.5 billion years ago – __________________________________________________ - History in Rocks o There is no direct evidence of the earliest years of Earth’s history o Oldest rocks formed about _____________________________ o Fossils – Clues to Past About _________ of the species that have existed are extinct Use fossils to learn about ancient species Fossil – __________ o o o ___________________________________________________ ____________________________________________________________________ Fossils form in many different ways Palentologists – Detectives to the past Paleontologists – ________________________________________________________________________ Gain knowledge about the kinds of org. that lived, learn about their __________________, gain knowledge about ____________________________ Fossil Formation 3 criteria that aids an organism into becoming a fossil: _______________________ – bones, teeth, shells, chiton (in exoskeleton) _______________________ – ________________________________________, scavengers can’t get to it, protection o Helpful if in _____________________________ _______________________ – ____________________________________ – less bacteria to break down tissues The soil compressed over time and hardens into ______________________ (form at low temps and pressure) Relative Dating ______________________________ Fossils are found in different layers – _______________________ ______________________________________________________ ____________________________________________________ ______________________________ - any feature that cuts across a body of sediment or rock is younger than the body of sediment that it cuts across Ex. ) Faults, fractures, dikes, sills _____________________________ - if one rocks contains fragments of another rock body it must be younger than the fragments of rock it contains OR the inclusions are older than the rocks with contain them _____________________________ - folds or tilts in rocks are younger than the rocks themselves o - - Radiometric Dating Utilize __________________________________ in rocks to find specific ages of rock __________________________________ cannot be directly radiometrically dated – _________________________________________________ can be dated Scientists compare how much radioactive isotope is in a rock compared with its daughter nuclei (what the isotope decayed into) Radioactive isotopes have a steady decay rate called its ___________________________ ________________________________________________________________________ o Carbon-14 Half-life = ___________________ Dates fossils less than _________________________ o Potassium-40 Half-life = _______________________ A Trip Through Geologic Time o Chronology, or calendar, of Earth’s history based on igneous/metamorphic rocks and fossils/sedimentary rocks forms the geologic time scale o The geologic time scale – divided into 4 sections Precambrian Paleozoic Mesozoic Cenozoic How the Earth was Made Video – A Trip through Geologic Time o _____________________ was the father of modern geology Thought that rocks could take ______________________________ to form Based on the rock formations, Hutton thought that the earth was _____________________of years old o A World of Fire How is it thought that the earth was formed? __________________________________________ ______________________________________________________________________________ Temperatures exceeded ______________ Fahrenheit According to Lord Kelvin, the earth was slowly cooling down. Before it cooled, the planet had once been completely _________________. Kelvin believed the Earth was at least _______________________ In 1911, Arthur Holmes used radioactivity to determine the age of the Earth Holmes determined that the Earth was _____________________________, the current accepted age of the Earth. o o o o A Water World The rare rock survivors from the first billion years of Earth’s life are called __________________ _______ billion years ago, most of the surface had solidified into dark volcanic rock…__________ was forming on the surface Where did the water come from? _________________________ _________________________ As water evaporated, it joined the carbon dioxide forming ________________________ This created the largest downpour the world has ever seen. The rain fell for _________________ ____________________ _______ billion years ago, over _____% of the Earth’s surface had become an ocean A Granite Planet _______ billion years ago, huge __________ oceans dominated; a new type of rock was creating the continental crust…this rock was ____________ The lighter density rock that made up the continental crust was ____________ while the denser rock that makes up the oceanic crust is ______________ Life during the Precambrian The oldest creature was the __________________; lived of sunlight and would fill the atmosphere with _______________; this organism can still be found today Dome-shaped structures – evidence of existence of photosynthetic organisms ____________________ created the mounds of the stromatolites ___________ billion years ago, these creatures dominated ________ billion years ago, as the iron left the oceans, the color changed from _________ to __________ 2.2 billion years ago, deep forces were rearranging the continents Plate Tectonics – Alfred Wegener – interested with the fossil/continent paradox o Proposed that the continents _________________________________________ the idea of continental drift o Detailed maps of the oceans floors showed rifts and trenches…demonstrated that the ocean floor is continually being reconstructed Where convection currents rise, ___________ forms and the plates are pushed _________, creating new _____________ Where the plates sink back down, it drags the oceanic crust with it, causing the ____________ to move with it o 1.0 billion years ago, a supercontinent formed named ______________ desolate, lifeless place Triggered _________________ - the biggest freeze our planet has ever seen (700 million years ago) Ice advanced to ________________ - and was ____ mile thick Marine organisms nearly wiped out of existance Life during the Paleozoic Rodinia broke apart Life forms evolved – became more complex and dangerous Cambrian Explosion The Burgess Shale – huge, important collection of _________________ o Three main org – trilobites, archaeocyathids (like armored sponges), and brachiopods Developed hard shells, skeletons, eyes and teeth __________________ formed acting like a UV shield 300 million years ago, second convergence of the continents – life emerged on land Tropical, swamplike conditions o Evidence of these swamplike conditions are found everywhere in the form of _________ o Plants emerged, then ____________, then ambitious ________________, and finally early _________________ took first steps on muddy shorlines The Permian extinction - biggest mass extinction in the planets history – 250 million years ago Rare mantle plume eruption Over _____% of species were driven to extinction o Life during the Mesozoic A new supercontinent _____________ dominated Oxygen and carbon dioxide rose to new peaks The animals that had survive the extinction, evolved into ________________ The name dinosaur means _______________________ Why were dinosaurs able to grow so much larger? ______________________________ Pangean supercontinent split into current positions Huge tropical forests were created due to ____________________________________________ More food allowed dinosaurs to specialize which foods they ate Second Mass Extinction at the end of the Cretaceous (65 million years ago) Smaller than that of the Permian Over than ______% of species disappeared Dinosaurs died in a single astronomical catastrophe o Tombstone layer contains rare element _____________ Most of this element comes from _______________________________ New theory for dinosaur extinction: hit by enormous ________________ over 6 miles in diameter (based on amount of iridium in tombstone layer) o Life during the Cenozoic The world of the ______________ and _____________ The first mammals begin to flourish The Alps, as well as other mountain ranges were created as a result of ______________________ __________________________ Erosion by ___________, ______________ and _______________ keeps the mountain ranges from reaching farther and farther into the sky 2 million years ago, the Earth entered the ______ ages – can last for tens of thousands of years Humans have dominated the last 10 thousand years o FUTURE: In _________________ years, a new ice age is thought to occur In 200 million years, a new supercontinent, _________________, is believed to be created 2 billion years ahead, our planet will look like ____________ Section 2: The Origin of Life - Origins: The Early Ideas o Spontaneous Generation – ________________________________________________________ Francesco ____ (1668) - ___________________________________________________ o - Pasteur’s Experiments Disproved the idea of a ____________________________________________________ ________________________________________________________________________ Used ___________________ Biogenesis – _____________________________________________________________ Idea became cornerstone of biology Origins: Modern Ideas o Simple Organic Molecules formed Simple organic molecules (that contained ___________________) formed They then organized into complex organic molecules such as ________________ _________________________________________________________________ ___________________ (1930’s) – Russian Scientist – believed life began in oceans Believed that ______________________________________________________ trigged chemical reactions to produce the small organic compounds Then rain washed molecules into oceans to form the _______________________ ______________________________________ (1953) – tested Oparin’s hypothesis _________________________________________________________________ (believed to be in early atmosphere) – sent an ___________________ through it – cooled mixture and one week later analyzed the results o Found presence of ____________________________________________ ____________________________________________________________ Supported Oparin’s hypothesis! o The formation of protocells Various experiments showed that if amino acids are heated without oxygen, they could then form proteins; similar process produces ATP and nucleic acids How did this become a cell? ___________________ (1992) – American scientist demonstrated how first cells might have occurred Heated solution of amino acids and produced protocells o Protocell – __________________________________________________ ___________________________________________________________ o The first true cells Prokaryote that formed from protocell Organisms were thought to be ___________________ and used some of the organic ___________________________________________________________ o o ___________________ evolved when food (organic molecules) started becoming scarce – similar to ___________________ Archeabacteria – ___________________________________________________ __________________________________________________________________ Early autotrophs probably made food by _________________________________ __________________________________________________________________ Photosynthesizing Prokaryotes Thought to have evolved ______________________________________ As first photosynthetic organisms increased in number, ___________________________ Evolved organisms with ___________________________ (fossil record indicated large ____________________________________________________~2.8 b.y.o.) Helped form ___________________to shield organisms from _______________ ___________________ and enabled evolution of more complex org. The Endosymbiont Theory ___________________ (1960’s) – American biologist – proposed that _______________ ________________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Evidence: o Bacteria and cyanobacteria similar to chloroplasts in size and photosynthetic abilities o mitochondria and some bacteria look similar o mitochondria and chloroplasts contain DNA that is similar to __________ ____________________________________________________________ o Mitochondria and chloroplasts have ______________________________ ____________________________________________________________
