130 likes | 308 Views
Plant Transport. Transport Overview. Water and minerals. Sugars. Vascular Tissue. Xylem Water Dissolved minerals Phloem Water Sugars Amino acids Hormones. Uptake of Minerals and Water. Lateral movement – soil to xylem Diffusion and active transport of minerals
E N D
Transport Overview Water and minerals Sugars
Vascular Tissue • Xylem • Water • Dissolved minerals • Phloem • Water • Sugars • Amino acids • Hormones
Uptake of Minerals and Water • Lateral movement – soil to xylem • Diffusion and active transport of minerals • Increased surface area • Root hairs • Mycorrhizae • Symplastic and apoplastic movement • All minerals must pass through a selective membrane • Casparian strip prevents direct apoplastic movement into the xylem
Bulk Flow Transport Through Xylem • Root pressure – pushing water • Active transport of minerals into root creates lower water potential • Water enters cells and is pushed up xylem • Transpiration – pulling water • Water evaporates from leaves • Water pulled up xylem because of cohesion of water molecules • Transpiration controlled by openings in leaf called stoma
Control of Transpiration • Stoma open • K+ enter guard cell • Cell becomes turgid from influx of water • Stoma closed • K+ pumped out of guard cell • Cell becomes flaccid from efflux of water
Photorespiration • Response to high heat and low water • Stoma close to prevent water loss causing low CO2 and high O2 levels in leaf • Carbon fixation low • Carbon is removed from RuBP to produce CO2 • Rubisco runs in reverse
Loading of Sucrose into Phloem • Transport is in either direction at different times • Transport from sugar source to sugar sink • Sugar is pumped from source to sieve tube member