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Water Potential exam Flashcards

Water Potential exam
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  • Water Potential
    The potential energy of water to move between two environments, determined by solute potential and pressure potential.
  • What drives the movement of water in plants?
    Water moves from areas of high water potential to areas of low water potential.
  • Solute Potential (Ψs)
    The solute concentration relative to pure water; high solute concentration means low solute potential.
  • What is the unit of measurement for water potential?
    Water potential is measured in megapascals (MPa).
  • Pressure Potential (Ψp)
    The physical pressure on water, which can be positive or negative.
  • What is the cohesion-tension theory?
    A theory that explains how evaporation creates negative pressure, pulling water upward through the xylem.
  • Transpiration
    The process of water evaporation from plant leaves, which helps pull water up from the roots.
  • What is turgor pressure?
    The pressure inside a plant cell due to water pushing the cell contents against the cell wall.
  • Casparian Strip
    A waxy layer in plant roots that regulates ion flow and solute concentration by blocking the apoplastic route.
  • How do plants transport sugars?
    Sugars are transported from sources to sinks via bulk flow in the phloem, facilitated by pressure differences.
  • Aquaporins
    Channels in cell membranes that facilitate the efficient movement of water.
  • What is the role of the Casparian strip?
    It forces water into endodermal cells, allowing them to act as filters to control ion flow and solute concentration.
  • Bulk Flow
    The movement of molecules along a pressure gradient, such as the movement of xylem sap or phloem sap.
  • What is the photosynthesis-transpiration compromise?
    The balance plants must find between conserving water and maximizing photosynthesis.
  • Root Pressure Theory
    A theory suggesting that positive pressure builds up in the root xylem due to increased water absorption relative to transpiration.
  • What is the function of stomata?
    Stomata control gas exchange and water evaporation by opening and closing.
  • Symplastic Route
    The pathway through the cytosol of cells, linked by plasmodesmata, for water movement.
  • What is the role of proton pumps in phloem loading?
    Proton pumps create a proton gradient that allows the proton-sucrose symporter to load sugar into the phloem.
  • Translocation
    The bulk flow of sugars from source to sink in the phloem.
  • What is guttation?
    The exudation of water droplets from leaves due to high root pressure.
  • Surface Tension
    The force between water molecules at the air-water interface, creating a tension across the surface.
  • What is the main driving force for water movement in the xylem?
    The cohesion-tension theory, where evaporation creates negative pressure that pulls water upward.
  • Phloem Loading
    The process of sugars entering the phloem via secondary active transport.
  • What is the significance of lignified cell walls in vascular tissue?
    Lignified cell walls provide structural support to withstand the negative pressure generated by water transport.
  • Capillary Action
    The ability of water to move through narrow spaces due to adhesion, cohesion, and surface tension.
  • What is the role of the xylem?
    The xylem transports water and dissolved minerals from the roots to the rest of the plant.
  • Photosynthesis-Transpiration Compromise
    The balance between conserving water and maximizing photosynthesis in plants.
  • What is the pressure flow hypothesis?
    A theory explaining the movement of phloem sap from source to sink due to pressure differences.
  • Cohesion
    The attraction between like molecules, such as water molecules clinging to each other.