osmosis and water potential ch 7 - principles of transport/osmosis and effects on cells ch 36...
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Osmosis and Water Potential
Ch 7 - Principles of Transport/Osmosis and Effects on Cells
Ch 36 Osmosis-Water Potential in plants
Problem:
“Cell”: 0.03 M sucrose0.02 M glucose
Environment:0.01 M sucrose0.01 M glucose0.01 M fructose
Permeable to simple sugars but not dissacharides.
Can we answer Q 6 a-e on page 141?
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“Tonicity” predicts direction of water movement
• Hypertonic• Hypotonic• Isotonic
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Effects on Cells
• Plant cells--What adaptations do plant cell have to deal with water balance?– Vocab: turgid, flaccid, plasmolysis
• Animal cells– Vocab: lysis
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Freshwater organisms--Unity and Diversity--Dealing with Water
Balance• Freshwater Fish…must osmoregulate and do not
drink (more later…)• Protista…contractile vacuole (eg. Paramecium)
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Ch 36 - Adaptations for Resource Acquisition
• Private Life of Plants excerpt: Water Transport in Plants
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private life of plants photosynthesis
Ch 36 - Transport in Vascular Plants
• Long distance transport by xylem (see pg 745)
•Tracheids
•Vessel elements
• Cell-to-cell transfer
• Individual cell uptake
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Three routes of transport• Apoplastic - external to cell membrane, through
walls and spaces• Symplastic - through cytoplasm and plasmodesmata• Transmembrane - passage across cell membranes
and wallsCell wall
Cytosol
PlasmodesmaPlasma membrane
Apoplastic route
Symplastic routeTransmembrane route
Key
ApoplastSymplast
What drives the movement of water?
• What is this a picture of? (hint: a major plant organ)
• What adaptations do plants have to control the route water takes?
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Investigating Solute Movement• Water follows ions…but how do ions become concentrated.• Active Transport
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Water Potential
• Water moves from higher water potential to lower water potential.
• Water potential= pressure potential plus solute potential
Model of Water Potential
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Water potential in a Hypertonic Solution
• Why is the cell losing water?
• What is the end result--what happens to the water potential inside/outside the cell?
Water potential in a hypotonic solution?
• What happens to the cell over time?
• Where is the water potential greater to begin?
• Which direction does the water move?
Now let’s go back and see why water moves up the tree?
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Loss of water drives movement
• Loss of water from stomata
• Cohesion-tension hypothesis
• Movement by Bulk Flow
• Online - Transpiration Case Study
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Regulation of Transpiration
• Where would we find guard cells ?
• Can you explain picture B using the concept of water potential?
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Review the Concept of Water Potential
• As a Class--Case Study 36: How are Water and Solute Potentials Calculated?
• On your own: Osmosis Lab Bench