S2S Tutors Quiz #1 Review.pdf

Processes of Evolution Get excited for Quiz 1!  What to Expect? 1. You are only expected to learn what we discuss in lecture, textbook information NOT covered in class is NOT fair game 2. Ensure the Examsoft/Examplify program is downloaded & works on your device...

Processes of Evolution Get excited for Quiz 1!  What to Expect? 1. You are only expected to learn what we discuss in lecture, textbook information NOT covered in class is NOT fair game 2. Ensure the Examsoft/Examplify program is downloaded & works on your device 3. Quiz format consists of 25 multiple choice questions, all in the format of true/false, normal MC and fill in the blank questions. Study Tips 1. Study Strategies - a. Find what works best for you! visual, auditory, reading/writing… b. We provide study groups, Office Hours, these review sessions etc. so take advantage! c. Space out your studying, don’t try to cram it all the night before  What Is Science? - Guided by natural law, explanatory by reference to natural law, testable against the observable world, conclusions are tentative, is falsifiable. ↳ Ultimately, Science is a system that builds and organizes knowledge in the form of testable explanations and predictions ↳ Body of knowledge based on facts and observation & a self correcting way of knowing through observation and experimentation - What is a scientific theory? 1. A Theory: A statement of what are held to be laws, principles, or causes of something known or observed a. Statement of Fact: a claim about a pattern that exists in nature b. Statement of Process: identities mechanism responsible for producing the pattern vs. 2. A Hypothesis: A proposed explanation made on the basis of limited evidence as a starting point for further investigation vs. 3. A Fact: A thing that is known or proven to be true Events in Earth’s History Can be Dated 1. Thinking about evolution on a long term scale requires “Deep Time Thinking” - Stratigraphy: Utilizing geological layers to elucidate the relative age of fossils - Radioactivity: The original concentration of an unstable isotope & the amount of daughter isotope remaining gives us an actual age of fossils (typically we use C14) - The half-life of an isotope is the time it takes to become the decay product Changes in Earth’s Physical Environment Affected the Evolution of Life 1. Land Masses have moved - Continental Drift & the mechanism of plate tectonics only became accepted in the 1960’s - Through fossil and tectonic evidence, tectonic movements are accepted to shape the Earth’s structure (Ex: Mountain formation, bodies of water, volcanoes, global climate, etc.) 2. Changes in Atmosphere Conditions 3. Sea levels 4. Varying Climate * Our geological record reflects that our world is and was a constantly changing planet  Bold = eon General Timeline Underline = era Italics = period 1. Hadean: hostile earth, no life 2. Archean: early life, photosynthesis development near end, mainly anaerobic processes 3. Proterozoic: prokaryotes diversified, great oxygenation, a. Ediacaran: aquatic, immobile life, first evidence of fossils 4. Phanerozoic: multicellular eukaryotes diversified a. Paleozoic: amniotic egg development = terrestrial vertebrates i. Cambrian (540 MYA): rapid diversification ii. Devonian (350 MYA): first forests iii. Permian (250 MYA): largest mass extinction, drop in oxygen levels, pangaea b. Mesozoic i. Cretaceous (65 MYA): asteroid mass extinction death of dinosaur c. Cenozoic ***Precambrian is NOT an eon. i. Quaternary: human evolution ***Refers to 3 eons before cambrian period.  The Early Earth 1. The Hadean - Prior to all life on Earth - Early Earth’s atmosphere did not contain oxygen (instead methane, hydrogen, ammonia) 2. Archean - 3.8 BYA: First life on Earth - All life must have had a anaerobic metabolism (Ex: Photosynthetic cyanobacteria) 3. Proterozoic - Diversified Prokaryotes and First Eukaryotic - Ediacaran Period (namesake the Ediacara Fossil Site): Immobile, aquatic, predator-less, simple life forms - The Great Oxygenation: Cyanobacteria are capable of splitting water molecules to utilize hydrogen for photosynthesis - This releases a lot of oxygen into Earth's atmosphere. - 2 Hypothesized Mechanisms of the Rise of Atmospheric Oxygen (Next Slide)  2 Hypothesized Mechanisms of the Rise of Atmospheric Oxygen 1. Atmospheric O2 levels initially rose slowly due to the rate of photosynthesis being balanced by respiration however, eventually O2 production via photosynthesis exceeds O2 consumption via respiration causing oxygen to accumulate in the atmosphere. 2. Initially, O2 produced by cyanobacteria reacted with other compounds in the atmosphere, preventing the accumulation of O2. Eventually, the compounds available to interact with oxygen decrease which increases the accumulation of oxygen in the atmosphere. Oxygenation graph ~320-275 MYA highest O2 levels Between devonian & permian periods in paleozoic era ~250 MYA O2 Drop ~2500 MYA = proterozoic Between permian and ~542 MYA = phanerozoic eon triassic period Hadeon & archeon Effects of Oxygen Accumulation 1. The formation of the Ozone Layer, allowing the expansion of life onto land. 2. Oxygen is toxic to some anaerobic organisms causing a shift into low O2 environment (Deep Sea Hydrothermal Vents) 3. Evolution of the aerobic metabolism The Cambrian Explosion! Rapid diversification - Organisms with complex body plans - Development of vision & predation with toothed jaws - The Burgess Shale site provides the best fossil evidence of this period - Dominant fossil being arthropods such as Trilobites Paleozoic Era: Cambrian Period ~542 MYA 1. First Terrestrial Plants (470 MYA): Changes the geosphere through oxygenating the atmosphere, soil formation, & diversifying environments on Earth - Vascularized Plants (ex: Ferns) - First seeded plants (ex: Pine tree) - Flowering Plants 2. The Age of Fishes - Tiktaalik (375 MYA): A fossil fish with a flattened head and unusual fins which allowed it to prop itself up in shallow water 3. First Forests - Spread of vascular plants that cause massive oxygenation & carbon sequestration causing global cooling **highest O2 levels 320-275 MYA** 4. First Land Arthropods Followed by Terrestrial Vertebrates - Fossil evidence of centipedes and arachnids being first to venture onto land - Evolution of amniotic egg was vital to vertebrates transitioning onto land Paleozoic Era: Permian Period ~300 MYA In phanerozoic eon Pangaea = 1 supercontinent all together as 1 land mass Fluctuations in weather Reptile diversification Rapid O2 level decrease (250 MYA) Massive volcanic eruptions end permian period ○ Forests die, swamps dry, oceans become acidic Largest mass extinction in history Extinction Extinction: last individual of a group (species, subspecies, family etc) dies and there is no lineage left on earth. Our current extinction rate is much greater than the normal expected extinction rate Mesozoic Era: Cretaceous Period ~300 MYA Phanerozoic eon After triassic & jurassic = dinosaurs Laurasia & gondwana drift = modern continents Meteorite ending cretaceous period ○ Crater site found in Yucatan peninsula ○ High iridium content found in ground Adaptive radiations: rapid rates of speciation among organisms that survive along with new adaptations for environmental pressures Ex. end of cretaceous led to mammal, bird and crocodile adaptive radiation Pangaea Ultima & Unity of Life Pangea Ultima: Expected to form in next 250 million years ○ Continents coming together ○ Would cause volcanic activity leading to increased CO2 and rising temperatures ○ Earth would be ultimately uninhabitable Unity of Life: all organisms on Earth share a single ancestor Evolution & Darwin Evolution: theory supported by facts, such as the processes by which populations have changed and continue to change over time ○ Ex. diversity of species and adaptations Ways evolution can be… ○ Observed- Changes in genetic compositions ○ Measured- Fossil records Darwin: doctor who studied nature, described variations in animal populations ○ Proposed natural selection ○ Defined adaptations & survival of the fittest ○ Had NO knowledge of genes or chromosomes