Vascular Plant Transport

Root and Leaf are friends Plant Transport Root need sugar Leaf make sugar Leaf need water Root have water Water go up Sugar go down Root and Leaf share Root and Leaf are friends

Transpiration

Transpiration: water transport The controlled release of water from a plant through stomata on the leaves resulting in movement of water from roots to leaves Water evaporates from spongy mesophyll Creates low water pressure in leaves Roots absorb water by osmosis Creates high water pressure in roots Water moves from high to low pressure From root to leaf

Xylem Transport Water moves by a variety of forces Cohesion: Adhesion: H-bonding to other water Adhesion: H-bonding to walls of xylem Capillary Action: Passive movement of water up through a narrow tube against gravity Transpiration pull: suction pressure from leaves

Factors Affecting Rate of Transpiration Sunny – increased light intensity Stomata open in presence of sunlight Warm – high temperature Increased evaporation Dry – low humidity Increase water vapor conc. gradient Windy Removes established humid locations around stoma

Regulation of Transpiration Guard Cells surrounding the stoma swell or shrink in response to the plants water needs. Up to 90% of water loss is through stoma Amount of water loss depends on density of stoma and their relative size.

Stoma close when guard cells lose water Flaccid state: K+ ions are transported out of the cell, water follows by osmosis Turgor state: K+ ions are transported into guard cells, water follows by osmosis

Abscisic Acid Plant hormone produced by root in response to water deficiency Stimulates guard cells into flaccid state, stoma closed

Xerophyte Adaptations Metabolic machinery can withstand increased temperature Low stoma densities Small, thick leaves (spines) Reduces surface area to volume ratio Thicker cuticles CAM physiology C02 absorbed at night, not day

Explain the process of water transport in vascular plants from root to leaf. Include tissues water moves through Forces that influence water movement Need for water movement

Phloem Transport Phloem is composed of living sieve tubes Sugars produced in leaves are actively pumped into sieve tubes Water follows by osmosis Results in high pressure in phloem Sugars exit phloem in roots and branch tips Results in low pressure in phloem Phloem solution moves from high pressure area to low From leaf to root, root to leaf Translocation is the movement of a biochemical in phloem

Phloem Transport