Patterns of Structure and Function in Plants
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Vascular Plants Have transport system –Water –Nutrients Allows for larger size
Organization of Vascular Plant Below ground root system –Roots for absorption Above ground shoot system –Stems & leaves Both have growth zones
Tissue Types of Vascular Plants (Differentiated Tissue) Vascular tissue –Circulatory system Ground tissue –Embeds vascular tissue –Most of plant tissue – Stores carbohydrates Dermal tissue –Protective covering
Meristem Tissue (Undifferentiated Tissue) Area of cell division Gives rise to other tissue types Results in plant growth
Vascular Tissue Xylem –Transports Water Nutrients –Conducting cells Tracheids Vessel elements –Cells die before becoming functional
Vascular Tissue Phloem –Conducts Carbohydrates Minerals –Cells Sieve-tube members –Living cells –Cytoplasm, no nuclei Companion cells –Nuclei –Secrete into & remove from sieve-tube members
Ground Tissue Three cell types –Parenchyma cells –Collenchyma cells –Sclerenchyma cells
Parenchyma Photosynthesis and storage Thin walled Most common cell type
Collenchyma Support tissue Unevenly thickened cells Bundles of supportive columns
Sclerenchyma Help in support and strength Dead, hollow cells with thick walls Fibers and sclerids
Covers plant Cells –Mostly epidermal (cuticle) –Guard cells Surround stomata –Trichomes Outgrowths of epidermis Bark replaces dermal tissue in woody plants Dermal Tissue
Meristematic Tissue Meristems –Areas of undifferentiated cells –Undergoes mitosis Primary growth –At tips of roots & shoots Secondary growth –Cylinder of meristematic tissue –Found in woody plants
Organs of Vascular Plants Roots Stems Leaves
Roots Absorb water & minerals Anchor the plant Storage (Some Roots)
Root Tissue Structure
Root Growth Meristem tissue at tip of root
Root Hairs Increase surface area for absorption
Types of Roots TaprootProp RootFibrous Root
Essential Nutrients Delivered by Roots
Need for Nutrients Plants produce carbohydrates from nonmineral nutrients (photosysthesis) Need nucleic acids, proteins, fats, & vitamins These are produced from carbohydrates and mineral nutrients Nutrient deficiency impairs growth
Stems Support leaves Transport fluids Have many shapes Storage
Stem Structures Nodes –Areas where leaves form on stem Internodes –Areas between nodes Lateral buds –Side shoots from stem
Stem Transport System
Vascular Cambium Growth tissue in woody stems New xylem & phloem is formed
Secondary Growth in Woody Stems
Wood of Trees Accumulated secondary xylem Hardwood – wood of dicot trees Softwood – wood of conifers Not accurate descriptions of wood density
Tissues in Tree Cross Section
Leaves Sites of photosynthesis Blade = flattened portion Petiole = stalk
Dicot vs. Monocot Leaves Monocot – veins parallel Dicot – net-like
Internal Leaf Structure
Openings in Leaf Tissue Used for respiration Stomata – openings Guard cells – regulate opening
Transpiration Water exiting leaf openings Fluids move by transpirational pull or (adhesion- cohesion-tension theory) –Water evaporates from airspaces within leaves –Water in mesophyle moves into empty spaces –Results in pull of water in xylem –Molecules pulled up (adhesion & cohesion) –Water (by osmosis) and minerals (by active transport) enter through root
Bulk Flow or (pressure flow) Fluid (sap) is also transported by phloem Transports products of photosynthesis Bulk flow = pressure flow –Companion cells actively transport sucrose into sieve tube member cells, water follows by osmosis –High pressure develops in phloem near the source –Low pressure in sink (where sucrose is used) – causing the rapid flow of sap
Nonvascular Plants No true roots, stems or leaves some have stems and leaf-like structures Outer layer of epidermis Parenchyma cells inside Some have central strand of water- conducting cells No other vascular tissues
Rhizoids Anchor some nonvascular plants No role in absorption
End chapter 24