Unisa Study Notes



PLANT STRUCTURE, GROWTH, AND DEVELOPMENTADVENTITIOUSA term describing any plant organ that grows in an atypical location, such as roots growing from stems.ANNUALA flowering plant that completes its entire life cycle in a single year or growing seasonAXILLARY BUDA structure that has the potential to form a lateral shoot, or branch. The bud appears in the angle formed between a leaf and a stem.BARKAll tissues external to the vascular cambium, consisting mainly of the secondary phloem and layers of periderm.BIENNIALA flowering plant that requires two years to complete its life cycle.BLADEThe flattened portion of a typical leafBUNDLE SHEATHA protective covering around a leaf vein, consisting of one or more cell layers, usually parenchyma.COLLENCHYMA CELLA flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining PANION CELLA type of plant cell that is connected to a sieve-tube member by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve-tube members.CORK CAMBIUMA cylinder of meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cellsCORTEXGround tissue that is between the vascular tissue and dermal tissue in a root or dicot stem.CUTICLEA waxy covering on the surface of stems and leaves that acts as an adaptation to prevent desiccation in terrestrial plants.DERIVATIVEA new cell that is displaced from an apical meristem and continues to divide until the cells it produces become specializedDERMAL TISSUE SYSTEMThe outer protective covering of plantsDETERMINATE GROWTHA type of growth characteristic of most animals and some plant organs, in which growth stops after a certain size is reached.ENDODERMISThe innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder.EPIDERMISThe dermal tissue system of nonwoody plants, usually consisting of a single layer of tightly packed cells.FIBERA lignified cell type that reinforces the xylem of angiosperms and functions in mechanical support; a slender, tapered sclerenchyma cell that usually occurs in bundles.FIBROUS ROOT SYSTEMA root system common to monocots consisting of a mat of thin roots spreading out below the soil surface.FUSIFORM INITIALa cell within the vascular cambrium that produces elongated cells such as tracheids, vessel elements, fibers, and sieve-tube members.GROUND TISSUE SYSTEMPlant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support.GUARD CELLSThe two cells that flank the stomatal pore and regulate the opening and closing of the pore.HEARTWOODOlder layers of secondary xylem, closer to the center of a stem or root, that no longer transport xylem sap.HERBACEOUSNonwoodyINDETERMINATE GROWTHA type of growth characteristic of plants, in which the organism continues to grow as long as it lives.INITIALA cell that remain within an apical meristem as a source of new cells.INTERNODEA segment of a plant stem between the points where leaves are attached.LATERAL MERISTEMA meristem that thickens the roots and shoots of woody plants.LATERAL ROOTA root that arises from the outermost layer of the pericycle of an established root.LEAFMain photosynthetic organ of most plantsLEAF PRIMORDIAFingerlike projections along the flanks of a shoot apical meristem, from which leaves arise.LEAF TRACEA small vascular bundle that extends from the vascular tissue of the stem through the petiole and into a leaf.LENTICELSmall raised area in the bark of stems and roots that enables gas exchange between living cells and the outside air.MERISTEMPlant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth.MERISTEM IDENTITY GENEA plant gene that promotes the switch from vegetative growth to flowering.MESOPHYLLThe ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis.MORPHOGENESISDevelopment of body shape and organizationNODEWhere the leaves are attached to a stemORGANA specialized center of body function composed of several different types of AN IDENTITY GENEPlant homeotic gene that uses positional information to determine which emerging leaves develop into which types of floral organs.PALISADE MESOPHYLLOne or more layers of elongated photosynthetic cells on the upper part of a leafPARENCHYMA CELLA relatively unspecialized plant cell type that carries out most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type.PATTERN FORMATIONThe ordering of cells into specific three-dimensional structures, an essential part of shaping an organism and its individual parts during development.PERENNIALA flowering plant that lives for many years.PERICYCLEThe outermost layer of the vascular cylinder of a root, where lateral roots originate.PERIDERMThe protective coat that replaces the epidermis in plants during secondary growth, formed of the cork and cork cambium.PETIOLEThe stalk of a leaf, which joins the leaf to a node of the stem.PHLOEMVascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plantPITA thinner region in the walls of tracheids and vessels where only primary wall is presentPITHGround tissue that is internal to the vascular tissue in a stem; in many monocot roots, parenchyma cells that form the central core of the vascular cylinderPLASTICITYAn organism's ability to alter or mold itself in response to local environmental conditions.polarityA LACK OF SYMMETRY Structural differences in opposite ends of an organism or structure, such as the root end and shoot end of a plant.POSITIONAL INFORMATIONSignals to which genes regulating development respond, indicating a cell's location relative to other cells in an embryonic structure.PREPROPHASE BANDMicrotubules in the cortex (outer cytoplasm) of a cell that are concentrated into a ring.PRIMARY GROWTHGrowth produced by apical meristems, which lengthen stems and roots.PRIMARY PLANT BODYThe tissues produced by apical meristems, which lengthen stems and roots.PROTOPLASTThe contents of a plant cell except the cell wallRAY INITIALA cell within the vascular cambrium that produces xylem and phloem rays, radial file that consist mostly of parenchyma cells.ROOTAn organ in vascular plants that anchors the plant and enables it to absorb water and nutrients from the soil.ROOT CAPA cone of cells at the tip of a plant root that protects the apical meristem.ROOT HAIRA tiny extension of a root epidermal cell, growing just behind the root tip and increasing surface area for absorption of water and minerals.SAPWOODOuter layers of secondary xylem that still transport xylem sap.SCLEREIDA short, irregular sclerenchyma cell in nutshells and seed coats and scattered through the parenchyma of some plants.SCLERENCHYMA CELLA rigid, supportive plant cell type usually lacking protoplasts and possessing thick secondary walls strengthened by lignin at maturity.SECONDARY GROWTHGrowth produced by lateral meristems, which thickens the roots and shoots of woody plants.SECONDARY PLANT BODYThe tissues produced by the vascular cambium and cork cambium, which thicken the stems and roots of woody plants.SHOOT SYSTEMThe aerial portion of a plant body, consisting of stems, leaves, and (in angiosperms) flowers.SIEVE PLATEAn end wall in a sieve-tube member, which facilitates the flow of phloem sap in angiosperm sieve tubes.SIEVE-TUBE MEMBERA living cell that conducts sugars and other organic nutrients in the phloem of angiosperms. They form chains called sieve tubes.SPONGY MESOPHYLLLoosely arranged photosynthetic cells located below the palisade mesophyll cells in a leaf.STELEThe vascular tissue of a stem or root.STEMA vascular plant organ consisting of an alternating system of nodes and internodes that support the leaves and reproductive structures.STOMAA microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.SYSTEMS BIOLOGYAn approach to studying biology that aims to model the dynamic behavior of whole biological systems.TAPROOT SYSTEMA root system common to eudicots consisting of one large, vertical root (the taproot) that produces many smaller lateral, or branch, roots.TERMINAL BUDEmbryonic tissue at the tip of a shoot, made up of developing leaves and a compact series of nodes and internodes.TRACHEIDA long, tapered water-conducting cell that is dead at maturity and is found in the xylem of all vascular plants.VASCULAR BUNDLEA strand of vascular tissues (both xylem and phloem) in a stem or leaf.VASCULAR CAMBIUMA cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem.VASCULAR CYLINDERThe central cylinder of vascular tissue in a root.VEINA vascular bundle in a leaf.VESSEL ELEMENTA short, wide, water-conducting cell found in the xylem of most angiosperms and a few nonflowering vascular plants; Dead at maturity; aligned end to end to form micropipes called vesselsVESSELA continuous water-conducting micropipe found in most angiosperms and a few nonflowering vascular plants.XYLEMVascular plant tissue consisting mainly of tubular dead cells that conduct most of the water and minerals upward from roots to the rest of the plant.ZONE OF CELL DIVISIONThe zone of primary growth in roots consisting of the root apical meristem and its derivatives. New root cells are produced in this region.ZONE OF ELONGATIONThe zone of primary growth in roots where new cells elongate, sometimes up to ten times their original length.ZONE OF MATURATIONThe zone of primary growth in roots where cells complete their differentiation and become functionally mature.PROTONEMAA mass of green, branched, one-cell-thick filaments produced by germinating moss spores.RHIZOIDFibrous organ that anchors nonvascular plants to the rootSORUSA cluster of sporangia on a fern sporophyllSTROBILIThe technical term for clusters of sporophylls known commonly as cones, found in most gymnosperms and some seedless vascular plants.SPOROCYTEA diploid cell, also known as a spore mother cell, that undergoes meiosis and generates haploid spores.CALYPTRAA protective cap of gametophyte tissue that wholly or partially covers an immature capsule in many mosses.PHRAGMOPLASTAn alignment of cytoskeletal elements and Golgi-derived vesicles across the midline of a dividing plant cell.PEATExtensive deposits of undecayed organic material formed primarily from the wetland moss Sphagnum. ................
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