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22 Cards in this Set
- Front
- Back
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Describe protobionts
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• aggregates of abiotically produced molecules surrounded by a membrane/-like structure
• exhibit simple reproduction and metabolism and maintain an internal chemical environment • Key step in origin of life on Earth * could have formed spontaneously |
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Describe the RNA-world and DNA-world
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First genetic material was RNA.
Early protobionts were self-replicating, catalytic RNA using resources DNA: more stable storage for genetic information, more accurate replication |
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What is the most difficult problem in accounting for the origin on life?
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Only nucleic acids replicate, but their replication requires the action of proteins that are encoded by the nucleic acids. How protein enzymes envolved is the greatest unsolved problem.
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What is the evidence for continental drift?
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Break up of Pangaea lead to allopatric speciation
Current distribution of fossils reflects movement of continental drift ex. same fossils found in S. America and Africa |
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What is the reason for the Ordovician mass extinction?
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Temperature drop, drop in sea level
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What are the adaptations of plants to move from water to land?
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Structural support
Internalized sex organs Vascular tissue for water transport Spores impermeable to water Spore-bearing structures |
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What is the reason for the Permian mass extinction?
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Volcanic eruptions in Siberia released poisonous gases into atmosphere, caused acid rain, caused oceans to become more acidic
Global warming decreased levels of oxygen |
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What is the reason for the Cretaceous mass extinction?
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Alvarez hypothesis: Impact of a large asteroid 65 million years ago
Evidence: Chixculub crater |
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What are some consequences of mass extinctions?
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Cause adaptive radiation
Change ecological communities and available niches Can take 5-100 million years to recover diversity |
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Describe the ancestor of mammals
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In the Late paleozoic, ammonoids give rise to synapsids, which include the ancestor of mammals
(Synapsids -> therapsids = mammal-like reptiles) |
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What are some evolutionary trends?
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Dinosaurs: body size increasing with many clades
Titanotheres: horn size |
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What order did hominids evolve in>
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A. afarensis
A. africanus Homo habilis: possible tools, cranium < 50% ours Homo erectus: fire Homo neanderthalensis: Interbred with sapiens Homo sapiens |
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What is the out of africa hypothesis?
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The dominant view of the origin of modern humans
H. sapiens arose in Africa and migrated out 50-100,000 years ago replacing the populations of H. erectus and H. neanderthalensis |
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What is the multiregional hypothesis?
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H. sapiens evolved as geographically separate but interbreeding populations stemming from world-wide migration of H. erectus out of Africa 2.5 million years ago
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Define vicariance
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separation of populations of widespread species by barriers arising from geology, climate, or habitat
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What do we use to describe a taxon's distribution?
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Vicariance, dispersal, and extinction
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Define biodiversity, species diversity, species richness, and species evenness
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Biodiversity: variation of life forms within a given ecosystem, biome, or Earth
Species diversity: # of different species in a particular area weighted by some measure of abundance Species richness: # of different species in a particular area Species evenness: relative abundance of each species which are represented in an area |
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Define neobiota
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Species that have been introduced since 1492 and have become well established
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Describe introduction of alien species.
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Can be on purpose- domestic animals- cattle
Pest control: Cane toad Can be unnoticed or accidnetal • zebra mussel in ballast water |
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Explain Williamson's tens rule.
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10% of all imported species escape to the wild
10% of these become established 10% of these become invasive |
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What are some consequences of alien species?
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Change in food web
Change of habitats Parasitism Disease Change of behavior Hybridization Evolution of aline and native species Ecological and economic damages: $120 billion/year |
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Study an example of an alien species talked about in class.
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Cane toad
Lake Victoria: Nil Perch |
