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37 Cards in this Set
- Front
- Back
Why does active transport of mineral ions require specific carrier proteins embedded in the cell membrane?
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Because soil is too dilute to create gradient
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What fuels the active transport of minerals ions?
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Cellular respiration
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What transports the ions across the plasma membrane?
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Proton pump
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What happens when ions are transported across the plasma membrane?
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H+ ions pumped out of cell and create pH gradient and voltage across the membrane to drive transport
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Two ways that water moves to stele (center) of the root
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Symplast and Apoplast
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"Living" part of cells
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Symplast
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"Nonliving" part of cells; extracellular pathway
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Apoplast
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Water moves from cell cytoplasm to cell cytoplasm through the plasmodesmata; goes all the way to the stele
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Symplast
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Water moves through cell walls without ever entering the cells in this method of water moving to the stele of the root
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Apoplast
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What blocks the apoplast pathway?
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The casparian strip
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Waxy layer of suberin around each cell of endodermis that is impervious to water and dissolved minerals
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Casparian stripe
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What do endodermal cells allow to enter the stele
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Water but they are selective about minerals entering (K+ can pass, but Na+ is blocked)
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What selectively pump ions out of the apoplast into the symplast so they may enter the xylem which requires energy
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Transfer cells
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The ascent of xylem sap depends on what?
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Transpiration and properties of water (cohesion/adhesion/H bonds)
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The evaporation of water from the aerial parts of a plant. Creates negative pressure
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Transpiration
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Xylem sap rises against gravity, driven by a gradient of _____ _____
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Water potential
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Water flows from an area of _____ water potential to an area of _____ water potential
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High; Low
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Osmotic pressure; occurs when transpiration is low, root cells pump ions into the stele
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Root pressure
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Root pressure causes water uptake by the stele which forces _____ (up the) _____
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Fluid up the xylem
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Formation of sap on the margins of leaves of grasses and small herbs caused by root pressure
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Guttation
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When does guttation occur?
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During the night when transpiration is low and more water enters leaves than is transpired
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Explains most water movement through xylem movement
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Cohesion-tension theory
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Evaporation from leaves due to stomata opening to obtain CO2, causes negative pressure (tension) to occur within the leaves and tissue
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Transpiration
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Transpiration causes _____ _____ to occur within the leaves and tissue
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Negative pressure
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Tree trunk diameter can decrease on a very hot day due to _____ _____
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Negative pressure
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Produces a single column of water from roots to leaves within xylem tissues
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Cohesion
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The rise of liquids in narrow tubes; results from forces of adhesion between hydrogen bonds of water and hydrophobic walls of xylem
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Capillary action
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Occurs as water molecules evaporate from the leaf surface by transpiration
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Bulk flow
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Driving force for ascent of sap through plants
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Gradient of water potential caused by the sun
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Four factors affective transpiration
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Temperature, humidity, air currents, and opening and closing of stomates
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Three things about transpiration
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supplies water to leaves assists in the transfer of minerals and results in evaporative cooling
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Stomates open when _____ and close when _____
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Turgid; flaccid
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Each stoma is surrounded by _____ _____ _____
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Two guard cells
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_____ _____ expand and buckle as water diffuses in and make an opening
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Guard cells
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_____ guard cells produce kidney-shaped guard cells that create an opening (stoma) between them
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Dicot
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_____ guard cells produce dumb-bell shaped guard cells to create opening
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Monocot
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Factors affect movement of stomata (5)
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Water availability to leaf, CO2 concentration, temperature, light, K+ ion concentration
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