Bio Ch. 13 – Flashcards
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The abundant remains of ammonites in Oklahoma indicate that Oklahoma was
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once covered by a shallow ocean.
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Relative dating uses ______ to estimate how old a fossil is.
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depth within rock layers
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If an isotope's half-life is 100 years, then
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in 100 years only half of the atoms in a sample of that isotope will remain.
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If similarities between two structures in different organisms reflect independent evolution, these structures are
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analogous
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The wings of a bat and a bird are examples of
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homologous structures.
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The femur in a snake and pelvis in a whale are examples of
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vestigial structures.
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The observation that most aquatic animals, like fish, penguins, and whales, all have streamlined bodies and fins or flippers for steering are a result of
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convergent evolution
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If many genes from two species differ in about 5% of their bases and substitutions occur at an estimated rate of 5% per one million years, approximately how many years have passed since the two species diverged?
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1 million.
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Why do different mutations accumulate in two species once they diverge?
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They can no longer mate and exchange mutated genes.
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Evolution occurs in
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Species
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What can be used as a molecular clock to estimate the time since organisms diverged from a common ancestor?
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DNA
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What is needed to estimate species relatedness with a molecular clock?
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DNA accumulates mutations at a regular rate
known mutation rate for a gene
the number of differences in DNA sequences for a gene in two species
the same gene identified in two species
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Scientists use the geologic timescale to
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divide the history of the Earth into eons and eras
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Paleontology
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is the study of fossil remains or other clues to past life
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relative dating
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which assumes that lower rock layers have older fossils than newer layers.
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Absolute dating
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uses chemistry to determine how long ago a fossil formed
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Radiometric dating
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is a type of absolute dating that uses radioactive isotopes.
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By determining the amount of carbon-14 in a fossil
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scientists can estimate when the organism lived.
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theory of plate tectonics
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Earth's surface consists of several rigid layers, called tectonic plates, that move in response to forces acting deep within the planet
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Two structures are homologous if
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the similarities between them reflect common ancestry.
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vestigial structure
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has lost its function but is homologous to a functional structure in another species
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Anatomical structures are analogous if
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they are superficially similar but did not derive from a common ancestor
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convergent evolution
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which produces similar structures in organisms that don't share the same lineage.
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Molecular clocks assign
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dates to evolutionary events.
