A) They peaked around 1950 and have been slowly decreasing since then.
B) They are high now but are not higher than the highest estimated levels during the last 420,000 years.
C) They are estimated to be higher now than at any time in the past 420,000 years.
D) They began to decrease when the use of CFCs stopped.
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Multiple Choice
A) global change.
B) global warming.
C) climate change.
D) net primary productivity.
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Multiple Choice
A) greenhouse gases.
B) ozone depleters.
C) endocrine disrupters.
D) trophic contaminants.
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True/False
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Multiple Choice
A) stop.
B) continue.
C) continue,but only in the lower trophic levels.
D) continue,but only in the higher trophic levels.
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Multiple Choice
A) They can have only localized effects.
B) They can be spread over large distances.
C) They cannot be bioaccumulated.
D) They cannot cause water transformations.
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Multiple Choice
A) cooling the ocean water by increasing the rate of evaporation.
B) warming the ocean water by decreasing the rate of evaporation.
C) increasing the acidity of ocean water because dissolved carbon dioxide makes the water more acidic.
D) decreasing the acidity of ocean water because dissolved carbon dioxide makes the water less acidic.
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Short Answer
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True/False
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Multiple Choice
A) produce a chain reaction of results that cannot always be predicted.
B) can all be predicted by ecologists who are experts in their field.
C) are very limited and probably won't affect humans.
D) will not be observed for decades.
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Multiple Choice
A) 10
B) 40
C) 70
D) 100
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Multiple Choice
A) During the last decade from 2001-2010,the highest temperatures in history have been recorded.
B) In Europe,bird and butterfly species have shifted their ranges northward.
C) The frequency of severe weather and the length of storm seasons have decreased.
D) Plants in northern latitudes have increased the length of their growing seasons.
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Multiple Choice
A) Yes,because it would halt global warming.
B) Yes,because it would increase ocean acidification.
C) No,because too much infrared radiation would be absorbed by Earth's surface.
D) No,because too much heat would be lost back into space.
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Multiple Choice
A) In the absence of forests,herbivore populations decline;without their respiration,less carbon dioxide is recycled into the atmosphere.
B) The carbon dioxide used by forest plants for cellular respiration would all be released into the atmosphere at once.
C) Trees naturally die and decompose,but when they are turned into lumber their carbon is prevented from recycling back to the atmosphere.
D) In the absence of forest plants,less carbon dioxide is removed from the atmosphere for use during photosynthesis.
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Multiple Choice
A) are bioindicators of the amount of ice in the polar bear's ecosystem.
B) contribute to atmospheric oxygen through photosynthesis.
C) absorb acid to prevent ocean acidification.
D) are an important source of vitamins for polar bears.
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Multiple Choice
A) organisms with narrow tolerances that can live in specialized environments
B) organisms with broad tolerances that can live in a variety of habitats
C) organisms that live in very stable environments
D) organisms that can live only if they form mutualistic relationships with other organisms
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Short Answer
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Multiple Choice
A) Some plant and animal species will migrate to cooler locations,whereas others will become extinct.
B) Increases in ocean evaporation and terrestrial rainfall will have a positive impact on the world's agricultural systems.
C) The frequency of severe weather will decrease.
D) The polar ice caps will increase in size.
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