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37 Cards in this Set
- Front
- Back
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What are the two subdiciplines for studying life on earth?
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Systematics - study of phylogeny
Paleontology - the study of ancient life and fossils |
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Fossil
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Physical trace left by an organism that lived in the past
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Fossil record
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Total collection of fossils that have been found throughout the world.
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Which rocks are the richest sources of fossils?
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Sedimentary rocks
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How is the sequence in which fossils have accumulated measured?
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Through the strata of sedimentary rocks.
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Why is the fossil record incomplete?
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Only a small proportion of all the organisms that ever existed left a fossil record.
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Habitat Bias
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Organisms that live in areas where sediments are actively being deposited are more likely to fossilize
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Taxonomic bias
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Organisms are more likely to decay slowly and leave fossil evidence
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Temporal bias
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More recent fossils are more common than ancient ones
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Abundance bias
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Organisms that are abundant, widespread, and present on Earth for a long time leave evidence much more often.
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2 classes of fossils?
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Trace, and Body
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What purpose do index or guide fossils serve?
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Help establish two locations have the same relative age by correlating strata from different locations.
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Precambrian era
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Hadean, Archean, and Proterozoic eons
Almost all life was unicellular and hardly any oxygen was present |
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Postcambrian era
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Phanerozoic eon which encompasses most multicellular eukaryotic life. Divided into three eras:
Paleozoic Mesozoic Cenozoic |
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Paleozoic era
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Fungi, land plants, and land animals
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Mesozoic era
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Dinosaurs
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Cenozoic era
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Age of mammals
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Carbon-14
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Isotope used to date fossils less that 75,000 years old.
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How did the study of fossils help establish the geologic record of Earth's history?
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Major boundaries between geological divisions correspond to extinction events in the fossil record.
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Stromatolites?
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Oldest known fossils, formed by the accumulation of sedimentary layers on those bacterial mats.
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What is the "oxygen revolution"
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When atmospheric oxygen began to be produced, about 2.7-2.3 billion years ago. It was produced by cyanobacteria altering the Earths atmosphere.
Caused the extinction of many prokaryotic groups |
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What cell structures make up Eukaryotic cells?
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Nuclear envelope, mitochnodria, endoplasmic reticulum, and cytoskeleton
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Endosymbiont theory?
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Mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells.
The ancestors of mitochondria and plastids probably gained entry to the host cell as undigested prey or internal parasites, in the process of becoming more interdependent, the host and endosymbionts would have become a single organism. |
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What properties of mitochondria and plastids support the endosymbiont theory?
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Inner membranes are similar to plasma membranes of prokaryotes
Cell division is similar in these organelles and some prokaryotes These organelles transcribe and translate their own DNA Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes. |
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What is the snowball Earth hypothesis?
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Periods of extreme glaciation confined life to the equatorial region or deep-sea vents from 750-580 mya
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Cambrian Explosion?
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Sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535-525mya)
First evidence of predator-prey interactions |
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What three points in time did the land masses of Earth form a supercontinent?
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1.1 billion, 600 million, and 250 million years ago.
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Theory of plate tectonics
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Earths crust is broken into enormous plates that are in constant motion driven by heat rising from the planets core.
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Continental drift
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Oceanic and continental plates can collide, separate, or slide past each other.
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Pangaea
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Supercontinent formed 250mya
Deepened ocean basins Reduction in shallow water habitat colder and drier climate inland |
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What are continental drift effects on organisms?
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Continent's climate can change as it moves north or south.
Seperation of land masses can lead to allopatric speciation |
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Exact definition of mass extinction
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60% of the species present are wiped out within 1 million years.
Function like genetic drift |
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Background Extinction
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Lower, average rate of extinction, representing the relatively constant, normal loss of some species. Typically occurs when normal environment changes, emerging diseases, or competition reduces certain populations to zero.
Result of Natural Selection |
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Describe the four related potentially interrlated hypothesis about the cause of the end-Permian extinction.
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Flood basalts called the siberian traps added enormous quantities of heat, CO2 and sulfur dioxide to the atmosphere, leading to global warming and the formation of toxic sulfuric acid
Oceans became completely or largely anoxic. Sea level dropped dramatically during the extinction event. Reducing the amount of habitat available for marine organisms. Low oxygen concentrations and high CO2 levels restricted terrestrial animals to small patches of low elevation habitats. |
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What is the impact hypothesis?
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An asteroid struck the Earth 65 mya, resulting in the extinction of an estimated 60-80% of the multicellular species alive and is well supported.
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What evidence supports the impact hypothesis?
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Iridium, shocked quartz, and microtektites found in rock layers dated to 65 mya as well as a huge crater off mexico's yucatan peninsula.
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Mass extinction can pave the way for adaptive radiations. What are adaptive radiations?
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The evolution of diversely adapted species from a common ancestor and occurs when rapid speciation in a single lineage is followed by divergence into many different adaptive forms.
May follow: Mass Extinction Evolution of novel characteristics Colonization of new regions |
