Plant structures What does a plant need for photosynthesis?

Regents Biology  Bring in:  light  CO 2 H2OH2O  Let Out: O2O2  Move Around:  sugars So what does a plant need for photosynthesis? 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ roots stem leaves

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 phloem (sugar) xylem (water) stomate palisades layer spongy layer cuticle epidermis guard cells cuticle epidermis vascular bundle (vein)

Regents Biology 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  CO 2 in for sugar production, remove waste O 2

Stomata  Openings found on underside of leaves.  Function of stomates (openings)  Gas exchange:  CO 2 in, O 2 out  Regulate water loss:  H 2 O 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”

Regents Biology Transpiration and gas exchange H2OH2OCO 2 O2O2 H2OH2O xylem (water) stomate guard cells O2O2  CO 2 in  O 2 out  water out

Regents Biology 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.