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Plant structures What does a plant need for photosynthesis? So what does a plant need for photosynthesis? Bring in: leaves light CO2 H2O Let Out: O2 Move Around: stem roots sugars 6CO2 + 6H2O + light C6H12O6 + 6O2 Regents Biology energy Organs used by plants • All vascular plants have 3 main organs – Roots – Stems – Leaves Roots Functions: Absorb water and dissolved minerals in soil and transport them up. Anchor the plant in the ground Storage of nutrients Stems • Functions: – Produce leaves, branches & flowers – Hold leaves up to the sunlight – Transport substances between roots and leaves – Storage of nutrients Leaves • Functions: – Photosynthesis • The structure of a leaf is optimized for absorbing light and carrying out photosynthesis. – Gas Exchange – Transpiration Leaf Structure cuticle epidermis vascular bundle (vein) xylem (water) phloem (sugar) palisades layer spongy layer epidermis cuticle stomate guard cells Function of Leaf Structures Cuticle waxy coating reduces water loss Epidermis “skin” protecting leaf tissues Palisades layer high concentration of chloroplasts collecting sun’s energy photosynthesis making ATP & sugars Spongy layer air spaces gas exchange CO2 in for sugar production, remove waste O2 Regents Biology Stomata Openings found on underside of leaves. Function of stomates (openings) Gas exchange: CO2 in , O2 out Regulate water loss: H2O out Function of guard cells open & close stomates guard cell stomate Guard cells & Homeostasis Maintains Homeostasis Plenty of water / during the day Stomata open Photosynthesis can occur Dry / very hot / at night: Stomata close Stops water loss Photosynthesis eventually stops Transpiration As Water evaporates from the stomata in the leaves, water is pulled up from roots. Cohesion: water sticks to water Adhesion: water sticks to sides of “tubes” Transpiration and gas exchange xylem (water) O2 H O 2 CO2 in O2 out Regents water out Biology CO2 stomate O2 H2O CO2 guard cells Transport in plants Vascular Tissue: The “bloodstream” of the plant, transporting water and nutrients throughout. Xylem: carries water UPWARD from the roots to every part of the plant Phloem: Transports products of photosynthesis (food) from leaves to rest of plant. Regents Biology