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Plant Anatomy AP Biology 2006-2007 Basic plant anatomy root root tip root hairs shoot (stem) nodes internodes buds terminal or apical buds axillary buds flower buds & flowers AP Biology leaves mesophyll tissue veins (vascular bundles) dermal 1 Roots Roots anchor plant in soil, absorb minerals & water, & store food fibrous roots (1) thin roots that spread out monocots tap roots (2) 1 large vertical root dicots root hairs (3) increase absorptive surface area AP Biology 2 3 Root Mycorrhizae “fungus roots” symbiotic relationship Found in most plants Aid absorbtion of water and minerals AP Biology Apical Meristems Region of Active growth -buds of shoots -tip of roots Produces Primary Growth- increase in length AP Biology Modified shoots stolons (strawberries) AP Biology tuber (potato) rhizome (ginger) bulb (onion) Leaf Functions photosynthesis glucose production gas exchange regulated by guard cells transpiration- loss of water by stoma AP Biology AP Biology Modified leaves tendrils (peas) AP Biology succulent leaves spines (cacti) colored leaves (poinsetta) Interdependent systems Both systems depend on the other roots depend on sugars produced by photosynthetic leaves shoots depend on water & minerals absorbed from the soil by roots AP Biology sugars water & minerals Plant TISSUES Dermal epidermis (“skin” of plant) single layer of tightly packed cells that covers & protects plant Ground most of plant tissue photosynthetic mesophyll, storage Vascular AP Biology transport system in shoots & roots xylem & phloem Plant CELL types in plant tissues Parenchyma photosynthetic cells, storage cells tissue of leaves, stem, fruit, storage roots Collenchyma unevenly thickened primary walls support Sclerenchyma AP Biology very thick, “woody” secondary walls support rigid cells that can’t elongate dead at functional maturity If I’d only had triplets! Parenchyma Parenchyma cells are unspecialized, thin, flexible & carry out many metabolic functions AP Biology all other cell types in plants develop from parenchyma Collenchyma Collenchyma cells have thicker primary walls & provide support AP Biology help support without restraining growth remain alive in maturity the strings in celery stalks are collenchyma Sclerenchyma Thick, rigid cell wall lignin (wood) cannot elongate dead at maturity Cells for support AP Biology xylem vessels xylem tracheids fibers vessel elements Xylem Vascular tissue has vessel elements and tracheids vessel element move water & minerals up from roots only cell walls remain empty pipes to efficiently move H2O transpirational pull dead cells Aaaah… Structure–Function again! tracheids AP Biology Phloem Aaaah… Structure–Function again! Living cells at functional maturity cell membrane, cytoplasm control of diffusion lose their nucleus, ribosomes & vacuole more room for specialized transport of liquid food (sucrose) Cells sieve tubes sieve plates — end walls — have pores to facilitate flow of fluid between cells companion cells nucleated cells connected to the sieve-tube help sieve tubes AP Biology Phloem: food-conducting cells carry sugars & nutrients throughout plant sieve tube companion cell sieve plate AP Biology living cells Phloem: food-conducting cells sieve tube elements & companion cells AP Biology Vascular tissue in stems dicot trees & shrubs AP Biology collect annual rings monocot grasses & lilies Vascular tissue in roots: dicot phloem AP Biology xylem Vascular tissue in roots: monocot xylem phloem AP Biology Secondary Growth Increase in the diameter of the plant Involves lateral meristems AP Biology Vascular cambium: produces secondary xylem (wood) Cork cambium: produces tough covering that replaces epidermis Bark = all tissues outside vascular cambium AP Biology
