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Plant transport. Chapter 36. Plant transport. Evolutionary changes Roots, Leaves, Stems Water Carbohydrates Minerals Light energy CO 2 O 2. Water transport. Roots Xylem Stomata Transpiration Cohesion & adhesion. Water transport. Flaccid: Limp Water loss Plasmolysis:
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Plant transport Chapter 36
Plant transport • Evolutionary changes • Roots, Leaves, Stems • Water • Carbohydrates • Minerals • Light energy • CO2 • O2
Water transport • Roots • Xylem • Stomata • Transpiration • Cohesion & adhesion
Water transport • Flaccid: • Limp • Water loss • Plasmolysis: • Cell membrane pulls away from cell wall • Due to water loss
Water transport • Turgid: • Firm • Water gain • Healthier plant
Water transport • Cell to cell (short distance) • Diffusion • Apolplast: • Continuum formed by cell walls • Symplast: • Continuum formed by cytoplasm of cells • Plasmodesmata: • Connection between cytoplasm
Cell wall Apoplastic route Cytosol Symplastic route Transmembrane route Key Plasmodesma Apoplast Plasma membrane Symplast
Water transport • Root hairs absorb water & minerals • Diffuse into apoplast or symplast • Pass through cortex • Endodermis (inner lining of cortex) • Casparian strip (waxy substance) • Controls flow water/ions to xylem • Forces flow to pass cell membrane
Casparian strip Plasmamembrane Apoplasticroute Vessels(xylem) Symplasticroute Roothair Epidermis Stele(vascularcylinder) Endodermis Cortex
Xylem • Movement based on bulk transport • Transpiration: • Negative pressure • Root pressure: • Positive pressure • Upward push of water/ions in xylem • Solar powered
Xylem • Guttation: • Loss of liquid through leaves • Ends of leaves • Increased root pressure
Stomata • H2O loss • CO2 intake
Guard cells • Opening & closing of the stomata • Dependent on turgor pressure of guard cells • Thicker inner cell layer • Causes bowing of the cell when turgid • Opens the stomata
Guard cells • Active K+ pump • Increased K+ in the guard cells • Increase in H2O in the guard cells • Turgid • Stomata opens • Decreased K+ leads to decreased H2O • Flaccid, stomata closes
Carbohydrate movement • Phloem (sieve-tube) • Moves from source to nearest sink • Carbohydrates enter sieve-tube cells • Active transport • Companion cells & parenchyma cells provide the ATP
Carbohydrate movement • Water potential differences-created • Water moves into the sieve-tube cells (osmosis) • Increased turgor • Moves carbohydrates to sink
Carbohydrate movement • Carbohydrates removed • Active transport • Water moves out (osmosis) • Water diffuses back to xylem • Or lost in transpiration