Click on a lesson name to select. Chapter 14 The History of Life Section 1: Fossil Evidence of Change Section 2: The Origin of Life

Click on a lesson name to select. Moon Fun Page Spare moon buggy tire!

Click on a lesson name to select. Early Earth / Origin of Life Earth formed 4.5 billion years ago Soon after a Mars sized meteor hit earth, broke stuff free that formed the moon For many millions of years after forming, earth was bombarded by meteors

Click on a lesson name to select. Life is a continuum extending from the earliest organisms through various branches to the great variety of forms alive today. Life on Earth began over 3.8 billion ago. –Earth forms -4.5 billion yrs –Earth molten / hit by meteors constatly until -4 billion yrs –Life shows up at -3.8 billion yrs – Life appeared only 200 million yrs after it was possible for life to exist 200m is really short span in geologic / evolutionary terms!

14.1 Fossil Evidence of Change Land Environments The History of Life Chapter 14  Earth 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.

Timeline of Earth History -4.5 billion yrs-2.25b yrs Present First Prokaryotic cell (-3.8)1 st Euk Cell 1 st Multicelled org 1 st animal -2b yrs -1.5b yrs -500m yrs 1 st plant (-450m yrs) 1 st Human -200,000 yrs Formation of EarthOxygen accumulates -4.5 b yrs -2.7b yrs Pangea -250m yrs Put these in order on test

All life today arises only by the reproduction of preexisting life, the principle of biogenesis. –(Biogenesis = life must come from life, can’t spontaneously appear) Although there is no evidence that spontaneous generation occurs today, conditions on the early Earth were very different. –There was very little atmospheric oxygen to attack complex molecules. –Energy sources, such as lightning, volcanic activity, and ultraviolet sunlight, were more intense than what we experience today.

More energy at the earth’s surface -UV (sun more intense) -Volcanoes -Lightning Early atmosphere not like the present -No Oxygen -CO2, H20,N2, CH4

***No oxygen is key to origin of life*** O 2 is a powerful oxidizer and would have degraded any organic molecules that would have happened to form Obviously reactive stuff

Without O2 organic molecules built up on early earth: Organic molecules formed in oceans and accumulated The oceans became big pools of organic molecules Meteor jam-packed with organic molecules Also additional organic mater was delivered to early earth via meteors

14.1 Fossil Evidence of Change Atmosphere The History of Life  The gases that likely made up the atmosphere are those that were expelled by volcanoes.  Water vapor (H 2 O)  Carbon dioxide (CO 2 )  Sulfur dioxide (SO 2 )  Carbon monoxide (CO)  Hydrogen sulfide (H 2 S)  Hydrogen cyanide (HCN)  Nitrogen (N 2 )  Hydrogen (H 2 ) Chapter 14

 The geological time scale is a model that expresses the major geological and biological events in Earth’s history. The Geologic Time Scale The History of Life  The geologic time scale is divided into the Precambrian time and the Phanerozoic eon.  Eras of the Phanerozoic eon include the Paleozoic, Mesozoic, and Cenozoic eras.  Each era is divided into one or more periods Fossil Evidence of Change Chapter 14

By comparing different sites, geologists have established a geologic time scale with a consistent sequence of historical periods. –These periods are grouped into four eras: Precambrian: oldest, first cell – simple animal Paleozoic: earliest fish, amphib’s, reptiles, mammlas Mesozoic: age of dinosaurs Cenozoic: classes of mammals, birds appear - today Boundaries between geologic eras and periods correspond to times of great change, especially mass extinctions, not to periods of similar length.

 Nearly 90 percent of Earth’s entire history, stretching from the formation of Earth to the beginning of the Paleozoic era about 542 million years ago Precambrian The History of Life  Autotrophic prokaryotes enriched the atmosphere with oxygen Fossil Evidence of Change Chapter 14

 The ancestors of most major animal groups diversified in what scientists call the Cambrian explosion. The Paleozoic Era The History of Life  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 Fossil Evidence of Change Chapter 14

The History of Life  A mass extinction ended the Paleozoic era at the end of the Permian period.  Between 60 and 75 percent of the species alive went extinct Fossil Evidence of Change Chapter 14

The Mesozoic Era The History of Life  Mammals and dinosaurs first appeared late in the Triassic period, and flowering plants evolved from nonflowering plants.  Birds evolved from a group of predatory dinosaurs in the middle of the Jurassic period.  About 65 million years ago, a meteorite struck Earth Fossil Evidence of Change Chapter 14

5. Explain the best theory that explains the extinction of the dinosaurs

The Cenozoic Era The History of Life  Mammals became the dominant land animals.  After the mass extinction at the end of the Mesozoic era, mammals of all kinds began to diversify Fossil Evidence of Change Chapter 14

Most orders of modern mammals, including primates, appeared million years ago. Humans diverged from other primates only 5 million years ago

Humans species showed up only ~200,000 yrs ago

 Plate tectonics describes the movement of several large plates that make up the surface of Earth. The History of Life  These plates, some of which contain continents, move atop a partially molten layer of rock underneath them Fossil Evidence of Change Chapter 14

The continents are “islands” of light rock that float on the liquid mantle below

Mid ocean ridges generate new crust that keeps continents moving

The continents drift about Earth’s surface on plates of crust floating on the hot mantle.

Earthquakes / volcanoes form at plate boundaries

In the movie “2012” the sun sends out extra radiation that warms earths core “like a microwave” Which causes plates to start moving around

About 250 million years ago, all the land masses were joined into one supercontinent, Pangaea, with dramatic impacts on life on land and the sea.

See note book file for proportional timeline

Clues in Rocks The History of Life  A fossil is any preserved evidence of an organism.  Most organisms decompose before they have a chance to become fossilized Fossil Evidence of Change Chapter 14 The fossil record is the ordered array in which fossils appear within sedimentary rocks.

7. Describe four different types of fossils :

The History of Life 14.1 Fossil Evidence of Change Chapter 14

Trace fossils: consist of footprints, burrows, or other impressions left in sediments by the activities of animals. These rocks are in essence fossilized behavior. –These dinosaur tracks provide information about its gait.

Mold/ Cast Mold : Impression left by organism (- impression) Cast : Object created when sediment fills mold (+ imp.)

Replacement: original material of organism is replaced with mineral crystals -leaves detailed replicas

Petrified fossils: Under the right conditions minerals dissolved in groundwater seep into the tissues of dead organisms, replace its organic material, and create a cast in the shape of the organism.

Amber fossils -Organism gets trapped in tree sap that dehydrates/ hardens over time into amber

Organic Remains type fossils If an organism dies in a place where decomposition cannot occur, then the entire body, including soft parts may be preserved as a fossil. –These organisms have been frozen in ice, or preserved in acid bogs.

Fossil Formation The History of Life  Nearly 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 Fossil Evidence of Change Chapter 14

Finding Fossils in SE MN Olmsted and Goodhue Co.’s have many road cuts that expose the “Decorah Shale” ( Shale rock is a type of sedimentary rock formed from mud/clay that is compacted together by pressure over time ) Decorah shale is grey / green Google: “Fossil Collecting in Twin Cities area” for more info (look for pdf)

8. Explain why the fossil record is very incomplete :

The discovery of a fossil depends on a sequence of improbable events. –First, the organism must die at the right place and time to be buried in sediments favoring fossilization. –The rock layer with the fossil must escape processes that destroy or distort rock (e.g., heat, erosion). –The fossil then has only a slight chance that it will be exposed by erosion of overlying rock. –Finally, there is only a slim chance that someone will find the fossil on or near the surface before it is destroyed by erosion too. The fossil record is a substantial, but incomplete, chronicle of evolutionary history

9. How do scientists know how old fossils are? / i.e. How do scientists date fossils? A. Relative dating: B. Absolute dating

Dating fossils The History of Life  Relative dating is a method used to determine the age of rocks by comparing them with those in other layers Fossil Evidence of Change Chapter 14

 Uses the decay of radioactive isotopes to measure the age of a rock Absolute Dating The History of Life  Radioactive isotopes that can be used for radiometric dating are found only in igneous or metamorphic rocks Fossil Evidence of Change Chapter 14

Under one hypothetical scenario this occurred in four stages: (1) the creation of small organic molecules; (2) joining these small molecules into polymers: (3) origin of self-replicating molecules; (4) packaging of these molecules into “protobionts.” How to make a cell:

14.2 The Origin of Life Origins: Early Ideas The History of Life  Spontaneous generation is the idea that life arises from nonlife.  Francesco Redi, an Italian scientist, tested the idea that flies arose spontaneously from rotting meat. Chapter 14

 The theory of biogenesis states that only living organisms can produce other living organisms. The History of Life  Louis Pasteur designed an experiment to show that biogenesis was true even for microorganisms The Origin of Life Chapter 14

Origins: Modern Ideas The History of Life  Simple organic molecule formation  The primordial soup hypothesis was an early hypothesis about the origin of life.  Organic molecules could have been synthesized from simple reactions.  UV light from the Sun and electric discharge in lightning might have been the primary energy sources The Origin of Life Chapter 14

 Stanley Miller and Harold Urey were the first to show that simple organic molecules could be made from inorganic compounds. The History of Life 14.2 The Origin of Life Chapter 14 Stanley/ Miller provided evidence that organics could have formed on early earth

Making Proteins The History of Life  Life requires proteins.  One possible mechanism for the formation of proteins would be if amino acids were bound to a clay particle The Origin of Life Chapter 14

Genetic Code The History of Life  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 The Origin of Life Chapter 14

Living cells may have been preceded by protobionts, aggregates of abiotically produced molecules (with lipids). Protobionts do not reproduce precisely, but they do maintain an internal chemical environment from their surroundings and may show some properties associated with life, metabolism, and excitability.

Early protobionts with self- replicating, catalytic RNA would have been more effective at using resources and would have increased in number through natural selection

Once primitive RNA genes and their polypeptide products were packaged within a membrane, the protobionts could have evolved as units.

Cellular Evolution The History of Life  Scientists hypothesize that the first cells were prokaryotes The Origin of Life Chapter 14

Photosynthesizing Prokaryotes The History of Life  Archaea are autotrophic.  They do not obtain their energy from the Sun.  Archaea also do not need or produce oxygen The Origin of Life Chapter 14

The History of Life  Many 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 The Origin of Life Chapter 14

The Endosymbiont Theory The History of Life  The ancestors of eukaryotic cells lived in association with prokaryotic cells.  The relationship between the cells became mutually beneficial, and the prokaryotic symbionts became organelles in eukaryotic cells.  This theory explains the origin of chloroplasts and mitochondria The Origin of Life Chapter 14

The History of Life 14.2 The Origin of Life Chapter 14

***Several lines of evidence support a close similarity between bacteria and the chloroplasts and mitochondria of eukaryotes***. –1. These organelles and bacteria are similar is size. –2. Enzymes and transport systems in the inner membranes of chloroplasts and mitochondria resemble those in the plasma membrane of modern prokaryotes. –3. Replication by mitochondria and chloroplasts resembles binary fission in bacteria.

–4. The single circular DNA in chloroplasts and mitochondria lack histones and other proteins, as in most prokaryotes. –5. Both organelles have their own transfer RNAs, ribosomes, and other molecules for transcription of their DNA and translation of mRNA into proteins. –6. The ribosomes of both chloroplasts and mitochondria are more similar to those of prokaryotes than to those in the eukaryotic cytoplasm that translate nuclear genes.

Prod: “Origin of the first cell” Create a booklet or poster with text & pictures and multiple pages (or a comic book format) to describe how first cell could have arisen. Things to include: 1.Making small molecules (What was early earth like? What was missing!?!) 2.Making proteins (polymers…how?) 3.Role of RNA 4.Origin of protobionts 5.Origin of Prokaryotes 6.Origin of Eukaryotes (endosymbiont theory)

The History of Life Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding lesson. Chapter 14

A. Tadpoles become frogs. B. A starfish can grow from a severed arm. C. Damp hay and corn create mice. D. From a tiny acorn, an oak can grow. Which is an example of the theory of spontaneous generation? The History of Life Chapter 14 Chapter Diagnostic Questions

A. sulfur B. nitrogen C. oxygen D. water vapor What gas do scientists think was absent from Earth’s early atmosphere? The History of Life Chapter 14 Chapter Diagnostic Questions

A. Cambrian B. Devonian C. Triassic D. Mesozoic In which period did the first land vertebrates appear? The History of Life Chapter 14 Chapter Diagnostic Questions

A. igneous B. metamorphic C. sedimentary D. volcanic In which type of rock do paleontologists search for fossils? The History of Life Chapter Formative Questions

A. absolute dating B. geological dating C. relative dating D. sedimentary dating Which dating method determines the age of rocks by comparing them to rocks in other layers? The History of Life Chapter Formative Questions

A. plate tectonics B. extensive glaciation C. increased volcanic activity D. meteorite impact Which geological change during the Mesozoic era had the greatest effect in shaping the course of evolution? The History of Life Chapter Formative Questions

A. biogenesis B. transgenesis C. primordial generation D. spontaneous generation At one time people believed that mold growing on a piece of cheese was created by the cheese. This is the idea of __________. The History of Life Chapter Formative Questions

A. It was digested by the host cell. B. It became an organelle in the host cell. C. It became a harmful parasite in the host cell. According to the endosymbiont theory, what may have happened to a prokaryotic cell that entered a host cell? The History of Life Chapter Formative Questions D. It was removed from the host cell by exocytosis.

A. chloroplast B. lysosome C. centriole D. ribosome An ancient prokaryote containing photosynthetic pigments that was engulfed by a host cell may have become a _________. The History of Life Chapter Formative Questions

A. 18 years B. 36 years C. 54 years D. 72 years Which is the half-life of the radioactive isotope shown in the graph? The History of Life Chapter 14 Chapter Assessment Questions

A. 2,857.5 years B. 7,576 years C. 11,460 years D. 5,730 years Study the graph. Determine the age of a rock if it contained 40% C-14. The History of Life Chapter 14 Chapter Assessment Questions

Use the illustration to infer what Pasteur’s experiment showed? The History of Life Chapter 14 Chapter Assessment Questions

A. Tilted bottles often spill. B. Microorganisms do not grow in flasks. C. Sterile liquids cannot spoil. D. Microorganisms can enter the tilted flask. The History of Life Chapter 14 Chapter Assessment Questions

A. absence of oxygen B. absence of food C. intense heat D. intense sunlight Which factor made it unlikely that life existed on Earth 4 billion years ago? The History of Life Chapter 14 Standardized Test Practice

A. fossilized microbes in volcanic rock For which fossil might a paleontologist most likely use carbon-14 to determine its age? The History of Life C. marine fossils found in a deep sedimentary layer D. a woolly mammoth frozen in a glacier since the last Ice Age Chapter 14 Standardized Test Practice B. dinosaur footprints found in sedimentary rock

A. 750,000 years B. 3 million years C. 4.5 million years D. 6 million years Beryllium-10 (Be-10) has a half life of about 1.5 million years. If a sample is analyzed and determined to contain ¼ of the original Be-10, what is the age of the sample? The History of Life Chapter 14 Standardized Test Practice

A. a large crater that was found B. a layer containing high levels of iridium C. the sudden appearance of mammals D. the sudden disappearance of dinosaurs Which provides the best evidence that a meteorite struck the earth 65 million years ago? The History of Life Chapter 14 Standardized Test Practice

In this experiment using water and the gases to simulate Earth’s early atmosphere, which was not one of the final products? The History of Life Chapter 14 Standardized Test Practice

A. amino acids B. nucleotides C. RNA molecules D. sugar molecules The History of Life Chapter 14 Standardized Test Practice

A. They are eukaryotes. B. They contain DNA. C. They carry out photosynthesis. D. They live in extreme environments. Why do scientists believe that archea are the closest relatives to Earth’s first cells? The History of Life Chapter 14 Standardized Test Practice

The History of Life Chapter 14 Glencoe Biology Transparencies

The History of Life Chapter 14 Image Bank

fossil paleontologist relative dating law of superposition radiometric dating half-life geologic time scale era period Cambrian explosion K-T boundary plate tectonics The History of Life Chapter 14 Vocabulary Section 1

spontaneous generation theory of biogenesis endosymbiont theory The History of Life Chapter 14 Vocabulary Section 2

The History of Life Chapter 14 Animation  Visualizing Geologic Time Visualizing Geologic Time  Continental Drift Continental Drift  Miller-Urey Experiment Miller-Urey Experiment