BSC 2010 Ch. 18 – Flashcards
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Which of the following statements describes a difference between the continents on Earth as scientists think they existed 540 million years ago and their existence today?
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The continents were located mainly in the Southern Hemisphere 540 million years ago; today they are distributed throughout both hemispheres.
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A student makes a comment that throughout human history, Earth has had a fairly constant existence and so there is no reason to think that Earth will change radically in the future. Which of the following statements best evaluates this student's thinking?
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The student's thinking is flawed because human history is very short and does not cover the length of time needed to observe extensive change on the planet.
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What pattern emerged from the long history of changes described in the tutorial?
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A pattern of environmental change followed by extinction or proliferation of life
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Of the following scenarios, which would provide the best analogy for describing continental drift?
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Sliding tiles on a number puzzle
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Which would be the best way to determine the absolute age of a collection of sedimentary rocks that are thought to be between 50 and 200 million years old?
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Paleomagnetic dating
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What is the most likely result of increased oxygen concentration on insects?
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Increase in body mass
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The cambrian explosion took place over ____ years
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more than fifty million
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Over geologic time, the concentration of O2 in Earth's atmosphere has increased. During the end of the ____ period, the O2 concentration decreased significantly and resulted in _____.
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Permian; mass extinction
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The ratio of 14C to its stable isotope, (12C), is relatively constant in living organisms and their environment, however, this ratio changes once an organism dies. In a fossil less than 50,000 years old you would expect the ratio of 14C to 12C to be
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lower, because the 14C is not replenished after death
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Scientists divide geological time into eras and periods. The ____ is the most inclusive, and the boundaries are based on ____.
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Era; changes in fossils
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Which group of organisms has been most affected by periods of increased glaciation?
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Marine life
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Gondwana is
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the southern part of the supercontinent after it broke in two
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For every described currently living species of organism, there is about ____ fossil species
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1/6
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The increase in the concentration of CO2 in Earth's atmosphere over the past 100 years
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is primarily caused by the burning of fossil fuels by humans
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Plates of Earth's crust
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can move via continental drift
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Consider the following series of strata in undisturbed sedimentary rocks: (1) Richmond is found below Talos and above Pitts; (2) Pitts is found above Somas; (3) Garett is above Talos. Based upon the principles of stratigraphy, where would you be most likely find the oldest fossils?
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Somas
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In the process of ____, the ____ oceanic plate is forced ____ the continental plate
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subduction; thinner; under
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What led to the mass extinction at the end of the Cretaceous period?
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A meteorite striking Earth
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Which of the following about oxygen is true?
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It made aerobic metabolism possible
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Coal is the fossilized remains of
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tree ferns and horsetails
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The half-life of 14C, a radioactive element of carbon, is approximately 5,000 years. The ratio of 14C to 12C in a fossil 25,000 years old would be about _______ that of a living organism today.
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1 to 32
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Around 5 million years ago, Earth was in the ____ era and the ____ period
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Cenozoic; Tertiary
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In the ____ period, fishes diversified and evolved jaws and club mosses, horse tails, and tree ferns became common. The earliest fossil terrestrial vertebrate and insects date from this period and there was a mass extinction at the end of the period that may have been caused by meteorite impacts.
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Devonian
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Mass extinctions occurred at the end of each of the following periods except the
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silurian
