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

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