Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
FOSSILS Provide Evidence of Change in organisms over time! What is a fossil? Preserved evidence of an organisms found This happens once they die, decompose, and become buried with sediment Sediments build up in layers and are subject to intense pressure. Therefore where will you find the oldest fossils? Deeper in the layers of sediments Fossil Types Trace Fossil- Indirect evidence Ex. Footprint, feces, burrows Molds and Casts- Impression or organisms Amber- preserved in tree sap Original Material- Mummification or freezing preserves bones, teeth, skulls, etc. What is a person called who studies fossils? Paleontologist How do we know how old a fossil is? Relative Dating- Determine dates of rocks by comparing them with those in other layers. Law of Superposition- young layers deposited on top of old layers Radiometric Dating- Decay of radiometric isotopes Half Life- time it takes for half of the original isotope to decay (Uranium 238 or Carbon 14 dating less than 60,000 yrs old) Geologic Time Scale Record of Earth’s history……..more than 4 billion years….broken into subdivision Largest to Smallest Eon, Era, Period, Epochs The Origin of Life Spontaneous Generation- 1668 Francesco Redi Tested idea that flies arose spontaneously from rotting meat. Observed maggots (fly larvae) appeared only in flasks that were open to flies. Closed flasks had no flies or maggots Not widely accepted Gave rise to biogenesis…only living organism can produce other living organisms (Louis Pasteur) Origin of Life: Modern Ideas Topic of ongoing research….3 ideas all developed due to a series of chemical events early in Earth’s History. 1. Stanley Miller simulated Earth’s early atmosphere and discovered organic compounds such as amino acids, sugars, and nucleotides. Simulation of Earth’s Early Atmosphere Meteorites Panspermia is a Greek word that translates literally as "seeds everywhere". The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may have originated through these "seeds". Hydrothermal Vents Hydrothermal Vents-deep sea where sulfur forms the base of a unique food chain What were the first cells like? The first cells are too old to be found as fossils so scientists predict the first cells were: Prokaryotic Survive in extreme environments Anaerobic (Oxygen present until 1.8 billion years ago) First Cells were photosynthesizing Found fossils of Cyanobacteria that were 3.5 bil years old Cyanobacteria eventually produced enough oxygen to support the formation of the ozone layer….leading to appearance of Eukaryotic Cells! How does the Theory of Endosymbiosis explain the origin of Eukaryotic Cells Prokaryotes might have lived inside Eukaryotes Ingested or internal parasites Relationship became mutually beneficial Prok. symbionts became organelles in Eurk (Chloroplast and Mitochondria) Evidence to support Endosymbiosis Mitochondria and Chloroplast have their own circular DNA just like prokaryotes Ribosomes that resemble those of prokaryotes Mitochondria and Chloroplast reproduce through binary fission just like prokaryotes This theory is widely accepted Fossils sediments Relative dating Radiometirc dating organisms Rock layers minerals age fossils Radioactive isotopes Check the correct column for each Paleozoice statementMesozoic Era Statement Precambria n Autotrophic prokaryotes enrich the atmosphere with oxygen Era X Primates evolve and diversify X It is divided into three periods: Triassic, Jurassic, and Cretaceous X Many types of insects, land plants, and the first land vertebrates appear X Mammals appear X Dinosaurs roam the Earth, and the ancestors of present day birds evolve X Reptiles appear Simple organisms, such as stromalites, live in marine ecosystems Cenozoic X X