Freshman Biology

 Evolution of  Macromolecules  Unicellular organisms  Eukaryotic cells  Multicellular organisms  Endosymbiotic theory- eukaryotic cells created from symbiotic communities of prokaryotes  Double membrane around Chloroplast and Mitochondria organelles  Some organelles contain their own DNA and DNA looks like prokaryote DNA  Reproduces like prokaryotes

 Studied by paleontologists  Remains of past dead organisms  Forms in sedimentary rock  Include  Eggs  Whole skeletons and pieces of them  Footprints  Even coprolite…(animal poop)!

 Change over Time  Over 99% of species that have lived on Earth are extinct  Extinct- all members of the species are dead  Extinction Extinction

 Relative Dating  Age of fossil is determined by its location compared to other fossils  Find relative age by comparing  Rock layer location- laid down in order from bottom (oldest) to top (youngest)  Index fossil location- fossil of known age  Must occur in a wide geographic area  Be easily recognizable  Only lived for a short period of time

 Radioactive Dating (Absolute age)  Age of fossil is determined by determining a ratio of radioactive elements in the rock around it  Radioactive elements decay into other elements  Decay is predictable and consistent  Half-life- the amount of time it takes for half of a sample to decay  Limits to C14 dating  <60,000 years old

 Divided into eras and then periods  Precambrian is 1 st Era  Life emerges-Prokaryotic cells  Paleozoic-2 nd Era  Jawed fish  Mesozoic  Mammals appear  Dinosaur extinction  Cenozoic  Mammals Rule