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13 Cards in this Set
- Front
- Back
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What is the primary force behind moving water upward through the xylem?
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Transpiration (water evaporating out of the top of the plant).
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What are aquaporins?
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Water channels in cell membranes.
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What are "potentials"?
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Ways of representing free energy that are used to predict which way water will move across a membrane.
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What are the two components to water potential?
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Physical forces (pressure potential) and solute concentrations (solute/osmotic potential).
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Water potential is equal to _______ plus ________. Does water move toward more negative or more positive water potentials?
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Pressure potential. Solute potential. More negative.
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What is the method of moving water up the xylem by actively transporting ions into the roots, increasing their solute potential?
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Root Pressure. It is used when transpiration cannot occur.
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What is guttation? Under what circumstances does it occur?
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The evacuation of water from leaves through specialized veins. When the plant is using root pressure to transport water.
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What is cohesion? Adhesion?
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The tendence of water to stick to itself (hydrogen bonds). The tendency of water to stick to other things.
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Stomata are meant to let ________ out and ________ in.
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Water vapor. CO2.
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What are aerenchyma? What problem do they solve?
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Loose parenchymal tissue with large air spaces. They allow the transport of oxygen, preventing the suffocation of plants in flooded areas.
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What is translocation?
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The transport of carbohydrates throughout the plant.
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What is the theory concerning the mechanism of translocation?
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The mass-flow hypothesis (aka pressure flow hypothesis or bulk flow hypothesis).
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What does the mass-flow hypothesis state?
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Carbohydrates at a "source" area are forced into small phloem tubes by phloem loading. Water diffusion and turgor pressure take the carbohydrates to the "sink".
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