PLANT CIRCULATION Leaves photosynthetic organs Stem contain vascular

PLANT CIRCULATION Leaves - photosynthetic organs Stem - contain vascular tissue Roots - gas exchange, H 2 O absorption, mineral uptake

LEAF CROSS SECTION cuticle epidermis pallisade mesophyll XYLEM spongy mesophyll H 2 O CO 2 Stoma

STEM CROSS SECTION Shoot Carbohydrates Phloem Xylem Root H 2 O

ROOT CROSS SECTION Carbohydrates Phloem Xylem H 2 O & Minerals

HOW DOES WATER MOVE? Adhesive Properties of Water Air Movement Atmospheric Pressure Capillary Action

TRANSPIRATION Driving Forces I. Root Pressure II. Evaporation

TRANSPIRATION The osmotic absorption of water in the plant roots, and pressure from water loss through the leaves that draws water up through the plants xylem vessels. CONFLICT: CO 2 Intake versus Transpiration Stomata must be open for CO 2 intake, but such opening also allows for water loss.

ROOT ABSORPTION Endodermis w/Casparian Strips Minerals -actively transported into roots. H 2 O -enters by osmosis. Casparian Strips - endodermal cells regulate passage of minerals into the vascular tissue, while water moves through or between cells. The strip is a belt of waxy material that prevents simple diffusion, and forces minerals and water to enter the vascular tissue through active transport by way of the endodermal cells

ENDODERMIS & CASPARIAN STRIPS EPIDERMIS ENDODERMIS CASPARIAN STRIP XYLEM

ROOT ABSORPTION Mycorrhizae The symbiotic interaction of root hairs and fungal hyphae provide increased surface area for water and mineral absorption and allow for more efficient transport of these into the plant. Guttation When root pressure is very high, it can force water up through The leaves of small plants, where the water exits through Structures as the ends of the leaf veins (hydathodes).

TRANSPIRATION Regulation by Stoma epidermal cell guard cell arrow direction represents movement of water -increase in guard cell K+ concentration causes increased turgor pressure, causing guard cell to bulge and stoma to open. -maintenance of open stoma is dependent upon ATP, in order to actively pump in K+. When this ceases, turgor pressure decreases and stoma close.