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8 Cards in this Set
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Biologists use the term ___ ___ to indicate the potential energy that water has in a particular environment compared with the potential with the potential energy of pure water at room temperature and atmospheric pressure |
Water potential |
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__ __ is the outward pressure exerted by the fluid contents of a living plant cell against its cell wall |
Turgor pressure |
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How is turgor pressure related to wilting in plants? |
If plants keep stomata open and leaf cells lose water faster than the water is replaced, positive turgor pressure inside living cells drops to 0. If the cell’s do not regain turgor quickly, they are at risk of dehydration and death. When an entire tissue loses turgor pressure, it will wilt |
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What are factors that affect water potential? |
Solute potential Pressure potential |
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___ ___ is the tendency of water to move by osmosis |
Solute potential |
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___ ___ is the tendency of water to move in response to pressure |
Pressure potential |
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How does water potential typically vary from soil to the top of the plant? |
Highest-lowest High water potential Soil (High if moist, low if extremely dry) Root (Med-High) Low water potential Leaf (Depends on transpiration rate; low when stomata are open) Atmosphere (Changes with humidity; usually very low) |
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Why do aphids not suck? |
Aphids insert a syringe-like mouthpart, stylet, into sieve-tube elements. The pressure on the fluid in these cells forces it through the stylet and into the aphids digestive tract. Excess water and sucrose that the aphid does not need is excreted out its anus as droplets of “honeydew”. This confirms the aphids do not actively suck the fluid. Phloem sap is under pressure, which forces to enter the aphid. |
