Chapter 35 Flashcards
A living cell that conducts sugars and other organic nutrients in the phloem of angiosperms; also called a sieve-tube member. Connected end to end, they form sieve tubes.
sieve-tube element
A type of plant cell that is connected to a sieve-tube element by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve-tube elements.
companion cell
(1) The dermal tissue system of nonwoody plants, usually consisting of a single layer of tightly packed cells. (2) The outermost layer of cells in an animal.
epidermis
A model of flower formation identifying three classes of organ identity genes that direct formation of the four types of floral organs.
ABC hypothesis
A tiny extension of a root epidermal cell, growing just behind the root tip and increasing surface area for absorption of water and minerals.
root hair
A root that arises from the pericycle of an established root.
lateral root
The vascular tissue of a stem or root.
stele
(1) The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency than the inner regions due to the presence of multiple microfilaments. (2) In plants, ground tissue that is between the vascular tissue and dermal tissue in a root or eudicot stem.
cortex
The outer protective covering of plants.
dermal tissue system
A transport system formed by xylem and phloem throughout a vascular plant. Xylem transports water and minerals; phloem transports sugars, the products of photosynthesis.
vascular tissue system
Ground 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 cylinder.
pith
A type of growth characteristic of most animals and some plant organs, in which growth stops after a certain size is reached.
determinate growth
(1) A shift from one developmental phase to another. (2) In plants, a morphological change that arises from a transition in shoot apical meristem activity.
phase change
Growth produced by apical meristems, lengthening stems and roots.
primary growth
An organ in vascular plants that anchors the plant and enables it to absorb water and minerals from the soil.
root
The two cells that flank the stomatal pore and regulate the opening and closing of the pore.
guard cells
Leaf cells specialized for photosynthesis. In C3 and CAM plants, mesophyll cells are located between the upper and lower epidermis; in C4 plants, they are located between the bundle-sheath cells and the epidermis.
mesophyll
A strong polymer embedded in the cellulose matrix of the secondary cell walls of vascular plants that provides structural support in terrestrial species.
lignin
In plant roots, the innermost layer of the cortex that surrounds the vascular cylinder.
endodermis
A bud at the tip of a plant stem; also called a terminal bud.
apical bud
A plant gene that promotes the switch from vegetative growth to flowering.
meristem identity gene
A cone of cells at the tip of a plant root that protects the apical meristem.
root cap
A continuous water-conducting micropipe found in most angiosperms and a few nonflowering vascular plants.
vessel
A short, wide water-conducting cell found in the xylem of most angiosperms and a few nonflowering vascular plants. Dead at maturity, vessel elements are aligned end to end to form micropipes called vessels.
vessel element
All tissues external to the vascular cambium, consisting mainly of the secondary phloem and layers of periderm.
bark
A main vertical root that develops from an embryonic root and gives rise to lateral (branch) roots.
taproot
A cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem.
vascular cambium
A segment of a plant stem between the points where leaves are attached.
internode
A meristem that thickens the roots and shoots of woody plants. The vascular cambium and cork cambium are lateral meristems.
lateral meristem
(1) A leaflike structure of a seaweed that provides most of the surface area for photosynthesis. (2) The flattened portion of a typical leaf.
blade
A short, irregular sclerenchyma cell in nutshells and seed coats. Sclereids are scattered throughout the parenchyma of some plants.
sclereid
Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support.
ground tissue system
A long, tapered water-conducting cell found in the xylem of nearly all vascular plants. Functioning tracheids are no longer living.
tracheid
Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth.
meristem
Vascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant.
phloem
A lignified cell type that reinforces the xylem of angiosperms and functions in mechanical support; a slender, tapered sclerenchyma cell that usually occurs in bundles.
fiber
A 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.
axillary bud
Growth produced by lateral meristems, thickening the roots and shoots of woody plants.
secondary growth
A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth.
collenchyma cell
A rigid, supportive plant cell type usually lacking a protoplast and possessing thick secondary walls strengthened by lignin at maturity.
sclerenchyma cell
A 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.
parenchyma cell
The development of a multicellular organism’s spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space.
pattern formation
Embryonic plant tissue in the tips of roots and buds of shoots. The dividing cells of an apical meristem enable the plant to grow in length.
apical meristem
The events involved in an organism’s changing gradually from a simple to a more complex or specialized form.
development
A vascular plant organ consisting of an alternating system of nodes and internodes that support the leaves and reproductive structures.
stem
Tendency for growth to be concentrated at the tip of a plant shoot, because the apical bud partially inhibits axillary bud growth.
apical dominance
A fingerlike projection along the flank of a shoot apical meristem, from which a leaf arises.
leaf primordium
A lack of symmetry; structural differences in opposite ends of an organism or structure, such as the root end and shoot end of a plant.
polarity
All of a plant’s roots, which anchor it in the soil, absorb and transport minerals and water, and store food.
root system
The stalk of a leaf, which joins the leaf to a node of the stem.
petiole
An integrated group of cells with a common structure, function, or both.
tissue
Vascular plant tissue consisting mainly of tubular dead cells that conduct most of the water and minerals upward from the roots to the rest of the plant.
xylem
A cylinder of meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cells.
cork cambium
One or more tissues organized into a functional unit connecting the organs of a plant.
tissue system
A type of growth characteristic of plants, in which the organism continues to grow as long as it lives.
indeterminate growth
A point along the stem of a plant at which leaves are attached.
node
A plant homeotic gene that uses positional information to determine which emerging leaves develop into which types of floral organs.
organ identity gene
The protective coat that replaces the epidermis in woody plants during secondary growth, formed of the cork and cork cambium.
periderm
A small raised area in the bark of stems and roots that enables gas exchange between living cells and the outside air.
lenticel
An end wall in a sieve-tube element, which facilitates the flow of phloem sap in angiosperm sieve tubes.
sieve plate
A 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.
stoma
The aerial portion of a plant body, consisting of stems, leaves, and (in angiosperms) flowers.
shoot system
