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97 terms

Chapter 9: Plant Organization and Function

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Angiosperms
flowering plant that produces seeds within an ovary, which eventually develops into a fruit
Root system
includes the main root that contains nitrogen-fixing bacteria
Shoot system
aboveground portion of a plant consisting of the stem, leaves, and flowers
Organ
combination of two or more different tissues performing a common function
Root hairs
projections from epidermal root-hair cells, increase absorptive surface of a root; extension of a root epidermal cell that increases the surface area for the absorption of water and minerals
Stem
main axis of a plant; usually the upright, vertical portion of a plant that transports substances to and from the leaves
node
occurs where one or more leaves are attached to a stem
Internode
region between the nodes; in vascular plants, the region of a stem between two successive nodes
Xylem
cells consist of nonliving cells that form a continuous pipeline for water nad mineral transport; vascular tissue that transports water and mineral solutes upward through the plant body, contains vesses elements and tracheids, contains 2 types of conducting cells-tracheids and vessel elements
Phloem
cells consist of living cells that join end to end for organic nutrient transport; vascular tissue that conducts organic solutes in plants
Leaf
lateral appendage of a stem, highly variable in structure, often containing cells that carry out photosynthesis
Blade
broad, expanded portion of a plant leaf
Petiole
the part of a plant leaf that connects the blade to the stem
Axillary bud
bud located in the axil of a leaf
Deciduous
plants that lose their leaves annually
Evergreen
tree that does not lose its leaves when seasons change
Meristematic tissue
all tissue types in a plant arise from this; undifferentiated embryonic tissue in the active growth regions of plants
Apical Meristem
causes an increase in length called primary growth; in vascular plants, masses of cells in the root and shoot that reproduce and elongate as primary growth occurs
Epidermal tissue
forms outer protective covering of a plant; exterior tissue, usually one cell thick, of leaves, young stems, roots, and other parts of plants
Ground tissue
fills the interior of a plant; tissue that constitutes most of the body of a plant; consists of parenchyma, collenchyma, and sclerenchyma cells that function in storage, basic metabolism, and support
Vascular Tissue
transports water and nutrients in a plant and provides support; transport tissue in plants, consisting of xylem and phloem
Epidermis
in plants, tissue that covers roots, leaves, and stems of a nonwoody organism; in mammals, the outer protective region of the skin
Cuticle
waxy layer covering the epidermis of plants that protects the plant against water loss and disease-causeing organisms
Root Hairs
extension of a root epidermal cell that increases the surface area for the absorption of water and minerals
Trichome
in plants, a specialized outgrowht of the epidermis, such as root hairs
Guard cell
results from cuticle reducing gas exchange in leaves; one of two cells that surround a leaf stoma
Periderm
protective tissue that replaces the epidermis of a stem and includes the cork and cork cambium
Cork
these cells compose periderm; outer covering of the bark of trees; made of dead cells that may be sloughed off
Lenticels
important in gas exchange between the interior of a stem and the air
Parenchyma
thin-walled, minimally differentiated cell that photosynthesizes or stores the products of photosynthesis
Collenchyma
plant tissue composed of cells with unevenly thickened walls; supports growth of stems and petioles
Sclerencyma
plant tissue composed of cells with heavily lignified cell walls; functions in support
Lignin
chemical that hardens the cell walls of plants
Vessel element
cell that joins with others to form a major conducting tube found in xylem
Tracheid
in flowering plants, type of cell in xylem that has tapered ends and pits through which water and minerals flow
Sieve-tube members
member that joins with others in the phloem tissue of plants as a means of transport for nutrient sap
Sieve
cluster of pores in the end walls, collectively called a sieve plate
Companion cell
has nucleus, each sieve-tube member has one; cell associated with sieve-tube members in phloem of vascular plants
Plasmodesmata
cytoplasmic channels that cross plant cell walls, aid in communication and transport between cells
Vascular cylinder
in dicot roots, a core of tissues bounded by the endodermis, consisting of vascular tissues and pericycle
Vascular bundles
in plants, primary phloem and primary xylem enclosed by a bundle sheath
Leaf veins
vascular tissue within a leaf
Cotyledon
seed leaf fot the embryo of a flowering plant; rovides nutrient molecules for the developing plant before photosynthesis begins
Monocot
member of the class of flowering plants called monocotyledones; have several common characteristics, including 1 cotyledon in the seed, scattered vascular bundles in stem, and flower parts in threes or multiples of three
Eudicot
a member of the class of flowering plants called eudicotyledones; have several common characteristics, including 2 embryonic leaves (cotyledons) in the seed, net-beined leaves, cylindrical arrangement of vascularbundles, and flower parts in fours or fives or multiples of four or five
Pinnate venation
major veins originate from points along centrally placed main vein (monocot)
Palmate venation
major veins originate at point of attachment of the blade to the petiole (eudicot)
Root Cap
protective covering of root tip, whose cells are constantly replaced as tey are ground off when the root pushes though rough soil particles
Epidermis
in plants, tissue that covers roots, leaves, and stems of a nonwoody organsim; in mammals, the outer protective region of the skin
Cortex
in plants, ground tissue bouded by the epidermis and vascular tissue in stems and roots; in animals, outer yer of anorgan, such as the cortex of the kidy or adrenal gland
Endodermis
inner germ layer of the embryonic gastrulathat become the lining of the digestive and respiratory tracts and associated organs
Casparian Strip
impermeable layer bordering four sides of root endodermal cells; prevents water and solute transport between adjacent cells
Vascular tissue
transport tissue in plants, consisitin of xylem and phloem
Pericycle
layer of cells surrounding the vascular tissue of roots; produces branch roots
Pith
parenchyma tissue in the center of some stems and roots
Primary Root
origianal root that grows straight down and remains the dominant root of the plant
Taproot
main axis of a root that penetrates deeply and is used by certain plants, such as carrots, for food storage
Fibrous root system
in most monocots, a mass of similarly sixed roots that cling to the soil
Adventitious Root
fibrous roots that develop from stems or leaves
Epiphyte
plant that takes its nourishment from the air because its placement on other plants gives it an aerial position
Root Nodule
structure on plan root tha contains nitrogen-fixinb bacteria
Mycorrhizae
mutually beneficial symbiotic relationship between a fungus and the roots of vascular plants
Symbiotic relationships assisting roots in taking up minerals
1) legumes have roots infected by nitrogen-fixing Rhixobrum bacteria
2) mycorrihizal association
terminal bud
bud that develops at the apex of a shoot
protoderm
outermost primary meristem-causes epidermis
ground meristem
produces2 tissues composed of parenchyma cells
procambium
produces first xylem cells and first phloem cells
Vascular cambium
in plants, lateral meristem that produces secondary phloem and secondary xylem
Herbaceous stems
mature nonwoody stems, exhibit only primary growth
Secondary Growth
occurs only in conifers and woody eudicots, increases girth of trunks, stems, branches, and roots
Bark
extenarl part of a tree, containing cork, cork cambium, and phloem
Cork Cambium
develops beneath epidermis; lateral meristem that produces cork
Wood
secondary xylem that builds up year after year in woody plants and becomes the annual rings
Spring wood
in this wide vessels transport sufficient water to growing leaves
Summer wood
has lower proportions of vessels cause moisture scarce
Annual Ring
tells age of stem, layer of wood (secondary xylem) usually produced during one growing season
Sapwood
outer annual rings where transport occurs
Heartwood
inner annual rings, no longer function in water transport
Stolon
stem that grows horizontally along the ground and may give rise to new plants where it contacts the soil
Rhizome
rootlike underground stem
Corms
bulbous underground stems tha lied dormant during winter
Mesophyll
this tissue composes body of a leaf; inner, theickest layer of a leaf consisiting of palisade and spongy mesophyll; the site of most photosynthesis
Eudicot leaves have these distinct regions
1) palisade mesophyll
2) spongy mesophyll
Palisade mesophyll
in a plant leaf, the layer of mesophyll containing elongated cells with many chloroplasts
Spongy mesophyll
layer of tissue in a plant leaf containing loosely packed cells, increasing the amount of surface area for gas exchange
Leaves can be arranged on a stem in these ways
1)alternate
2) opposite
3) whorled
cohesion-tension model
replies on properties of water; explanation for upward transport of water in xylem based upon transpiration-created tension and the cohesive properties of water molecules
Movement of water and minerals in plant
enters root, enters xylem, carried upward to top of tree
cohesion
tendency of water molecules to cling together
adhesion
ability of water, a polar molecule, to interact with the molecules making up the walls of the vessels in xylem
transpiration
exerts a tension which draws water column up in vessels from roots to leaves; plant's loss of water to the atmosphere, mainly through evaporation at leaf stomata
flow of potassium ions in guard cells
K+ flows in and causes water to follow by osmosis and stomata to open
Girdling
removal of a strip of bark frowm around a tree
Pressure-flow model
explanation for phloem transport; osmotic pressure flowing active transport of sugar into phloem brings a flow of sap from a source to a sink
Sieve-tube members
form a continuous pathway for organic nutrient transport thoughout a plant
Source
in the pressure-flow model of phloem transport, the location (leaves) of sugar production
Sink
in the pressure-flow model of phloem transport, the location (roots) from which sugar is constantly being removed