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16 Cards in this Set
- Front
- Back
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by what methods does water move?
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transpiration and cohesion-tension theory
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what happens in transpiration?
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water is absorbed by root hairs, water flows through xylem, then exits through stomata
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what direction does water move with cohesion-tension theory?
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uphill through the plant
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what is translocation?
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the movement of food substances by the sieve tubes of the phloem
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which directions can food substances move in the phloem?
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both directions in thw phloem
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food is usually what substance?
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sucrose and is moved from a "source" to a "sink"
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what is the main source of atmospheric water?
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evaporation from the sea
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what happens when humans destroy forests and vegetation?
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they change the amount of water vapor in the air
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what are detrivores?
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organisms that derive energy from organic wastes and dead organisms
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what would happen if the detrivores were killed off?
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carbon would accumulate in the soil and have less carbon in the air, causing plants to die
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80% of the atmosphere is composed of what?
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N2(double bonded nitrogen)
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plants can only use nitrogen in what form?
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nitrate ions (NO3-) or ammonium ions (NO3+)
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what do plants use nitrogen for?
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to make amino acids and proteins; nitrogen is then available to consumers
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what will raise the CO2 in the atmosphere and cause global warming?
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an increase in the burning of fossil fuels will raise the level of CO2 in the atmosphere
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why is phosphorous cycling more localized than carbon or nitrgen cycling?
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because phosphorous cycling is almost entirely within the rocks and the soil
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what does the greenhouse effect do?
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CO2 lets the sunlight through but retainsthe heat generated by the sun; earth needs some greenhouse effect or earth would be too cold to survive
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