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• Defined: Collection of every known fossil • Most fossils found in sedimentary rock • Age determined by depth – Law of Superposition: new rock forms on top of older rock • Evidence Conclusions: – 1) Newer fossils are more complex – 2) Common ancestors: similarities between ancient & modern life Comparing old fossil to modern life shows change Ancient Kelp Modern Kelp Radiometric Dating • Helps determine age of fossils • Isotopes: atoms of the same element with differing neutrons – Ex: 12C and 14C 12C = 6 protons + 6 neutrons 14C = 6 protons + 8 neutrons Both are Carbon • When organism dies: 14C starts to decay • Fossil age determined by comparing ratio of 12C to 14C Dinosaurs extinct Land animals (amphibians) Fish (first vertebrates) Apes Dinosaurs appear Amniotic egg (reptiles) Land plants & fungi Multicellular plants Outside links Link 1 Link 2 Unicellular eukaryotes Scale: 1 minute = 3 million years Land prokaryotes (LUCA) prokaryotes 24 Hour Earth Timeline Whale Evidence Reptile Fish evidence Evidence Long Teeth spine Scales Amphibian evidence Land Bird Evidence Eyes on top of head Wolf-like Wishbone teeth Found in dried up Bony tail Fins oceans Found in dried-up oceans Wrist Hind bones Features legs • AKA: Transition Fossils – Archaeopteryx: shares both bird & reptile features – Basilosaurus: shares whale & land mammal features – Tiktaalik: shares fish & amphibian features • Evidence Conclusion : Indicates common ancestry • Defined: similar body structures with very different functions • Different environments lead to adaptations – Ex: The forelimbs of animals • Evidence Conclusion : Indicates common ancestry • Defined: Organs which have lost most or all their original function • Vestigial Human Parts: – Gill slits = once used to breath oxygen in water – Yolk sac = once used to nourish developing embryo – Tailbone = once used for balance – Appendix = once used to digest plants – Wisdom teeth = once used to grind plant tissue • Evidence Conclusion : Indicates common ancestry Human Embryo w/ Vestigial Structures Pythons have tiny femurs (leg bone) • • • • DNA, RNA, proteins compared Genetic code same for most life More related species have more similar biochemistry Evidence Conclusion : Indicates common ancestry • Different species show similar development patterns • Different body plans become noticeable later in development • Evidence Conclusion : Indicates common ancestry Bacteria Fungus • Antibiotics: drugs designed to kill bacteria – Obtained from fungi • Antibiotic Resistance: Bacteria are adapting to the use of antibiotics – Misuse of antibiotics speeds up the process – Importance: Bacteria infections are becoming harder to treat – Example of natural selection Antibiotic Resistance Bad The antibiotics don’t kill the bacteria, that’s why there is no clear area around them. Good The antibiotics kill the bacteria, so the area around them are clear • Pesticides – Chemicals designed to kill pests (rodents, insects, etc…) – Pesticides sprayed on crops to kill pests • Pesticide Resistance: pests are adapting to the use of pesticides – “Strong” pests survive to reproduce – Importance: Crops are being destroyed by pests • First life on earth were prokaryotes (bacteria) • Changing environments lead to adaptation • Much evidence indicates life has common ancestors