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Plant Structure and Function Ch. 35 http://www.uic.edu/classes/bios/bios100/labs/plantbod.gif
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Morphology of a Flowering Plant Root system and shoot system are connected by vascular tissue that is continuous throughout plant
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Monocots vs. Dicots
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http://waynesword.palomar.edu/images/monocot3.gif http://www.biologie.uni-hamburg.de/b- online/library/onlinebio/monocot_flower.gif http://www.biology4kids.com/misc/photos /dicotflower1.jpg http://waynesword.palomar.edu/images/monocot3.gif
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Nucleus Plant Cell Chloroplast Cell Wall
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Roots Functions –Anchor plant in the soil –Absorb water and minerals –Store food
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Root Structure
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Root Systems TaprootFibrous root
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Red mangrove growing in seawater Adventitious prop roots support and securely anchor this shrub in the mud and loose sand of tidal waters. Close-up view of prop roots Numerous pores called lenticels which provide gas exchange and an additional source of oxygen for the submersed roots. http://waynesword.palomar.edu/images/mangro3b.jpg
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Cortex Epidermis Developing lateral root Vascular cylinder -xylem -phloem
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Modified Roots Prop root Buttress roots. Aerial roots Storage roots.
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Stems Functions –Support –Transport –Storage
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Monocot arrangement
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Dicot arrangement
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Proximity of terminal bud inhibits growth of axillary buds (Apical dominance) http://www.answers.com/topic/redtip9845-jpg-1
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Modified Stems Stolons—allow asexual reproduction Bulbs—store food Tubers—store food Rhizomes—horizontal stem
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Leaves Leaf structure –Shape –Size –Edges
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Leaf Structure Mesophyll
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Stomata
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Modified Leaves Tendrils—allow plant to cling to support Spines—reduces water loss
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Modified Leaves Storage—modified for water storage (succulents) Bracts—attracts pollinators
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Modified Leaves Reproductive leaves— produce adventitious plantlets which fall off and take root
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Tissue Systems --cube-shaped, thin and flexible cell walls --function in photosynthesizing and storing organic products and wound healing --elongated, thicker cell walls --cells grouped in strands or cylinders to support leaves and stems (parts that are still growing) --cells have rigid, thick walls with lignin --at maturity, consists of dead cells --supports and strengthens plant 1. Ground System Parenchyma Collenchyma Sclerenchyma
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Tissue Systems 2. Vascular System Xylem -Conducts water and minerals from roots to plant -composed of dead cells that form water-pipe system Phloem -Conducts food throughout plant -composed of living cells arranged into tubules
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Water-conducting Cells of Xylem
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Sugar-conducting Cells of Phloem
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Sheath of sclerenchyma phloem xylem parenchyma
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Tissue Systems 3. Dermal Tissue System - Forms the outer covering of plants Epidermis-outer layer of cells covered by waxy cuticle Stomata-structures that regulate passage of gases into/out of plant
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Meristems: Primary Growth Growing region where cells actively divide Apical meristems- grow in length at tips of stems and roots
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Lateral meristems Add thickness to woody plants, a process called secondary growth Two lateral meristems –vascular cambium adds layers of vascular tissue called secondary xylem (wood) and secondary phloem –cork cambium replaces the epidermis with periderm, which is thicker and tougher
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Primary Growth in Roots
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Primary Growth in Shoots
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Secondary growth occurs in stems and roots of woody plants but rarely in leaves Vascular cambium Produces secondary xylem and phloem Cork cambium Produces tough, thick covering for stems and roots Replaces epidermis
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Anatomy of a Tree Trunk As a tree or woody shrub ages, the older layers of secondary xylem, the heartwood, no longer transport water and minerals The outer layers, known as sapwood, still transport materials through the xylem
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Growth, morphogenesis, and differentiation produce the plant body The three developmental processes of growth, morphogenesis, and cellular differentiation act in concert to transform the fertilized egg into a plant
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Growth: Cell Division and Cell Expansion By increasing cell number, cell division in meristems increases the potential for growth Cell expansion accounts for the actual increase in plant size
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The Plane and Symmetry of Cell Division The plane (direction) and symmetry of cell division are immensely important in determining plant form If the planes of division are parallel to the plane of the first division, a single file of cells is produced
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The Plane and Symmetry of Cell Division If the planes of division vary randomly, asymmetrical cell division occurs
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The Plane and Symmetry of Cell Division The plane in which a cell divides is determined during late interphase Microtubules become concentrated into a ring called the preprophase band
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Genetic Control of Flowering Flower formation involves a phase change from vegetative growth to reproductive growth It is triggered by a combination of environmental cues and internal signals Transition from vegetative growth to flowering is associated with the switching-on of floral meristem identity genes
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Plant biologists have identified several organ identity genes that regulate the development of floral pattern
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The ABC model of flower formation identifies how floral organ identity genes direct the formation of the four types of floral organs
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