Chapter 35B Study Guide
Plant Tissues

1. Plant organs are composed of three tissue systems: dermal, vascular, and ground.
•	Each organ of a plant has three tissue systems: dermal, vascular, and ground.
•	Each system is continuous throughout the plant body.
•	The  __________  tissue is the outer covering.
•	In nonwoody plants, it is a single layer of tightly packed cells, or  __________ , that covers and protects all young parts of the plant.
•	The epidermis has other specialized characteristics consistent with the function of the organ it covers.
•	For example, the root  __________  are extensions of epidermal cells near the tips of the roots.
•	The epidermis of leaves and most stems secretes a waxy coating, the  __________ , which helps the aerial parts of the plant retain water.
•	In woody plants, protective tissues called  __________  replace the epidermis in older regions of stems and roots.
•	__________  tissue, continuous throughout the plant, is involved in the transport of materials between roots and shoots.
•	__________  conveys water and dissolved minerals upward from roots into the shoots.
•	__________  transports food made in mature leaves to the roots; to nonphotosynthetic parts of the shoot system; and to sites of growth, such as developing leaves and fruits.
•	The vascular tissue of a root or stem is called the  __________ .
•	In angiosperms, the vascular tissue of the root forms a solid central  __________  __________ , while stems and leaves have  __________  __________ , strands consisting of xylem and phloem.
•	__________  tissue is tissue that is neither dermal tissue nor vascular tissue.
•	In eudicot stems, ground tissue is divided into  __________ , internal to vascular tissue, and  __________ , external to the vascular tissue.
•	The functions of ground tissue include __________ , __________ , and  __________ .
•	For example, the cortex of a eudicot stem typically consists of both fleshy storage cells and thick-walled support cells.
4. Plant tissues are composed of three basic cell types: parenchyma, collenchyma, and sclerenchyma.
•	Plant cells are differentiated, with each type of plant cell possessing structural adaptations that make specific functions possible.
•	Cell differentiation may be evident within the  __________ , the cell contents exclusive of the cell wall.
•	Modifications of cell  __________  also play a role in plant cell differentiation.
•	We will consider the major types of differentiated plant cells: parenchyma, collenchyma, sclerenchyma, water-conducting cells of the xylem and sugar-conducting cells of the phloem.
•	Mature  __________  cells have primary walls that are relatively thin and flexible, and most lack secondary walls.
•	The protoplast of a parenchyma cell usually has a large central  __________ .
•	Parenchyma cells are often depicted as “typical” plant cells because they generally are the least specialized, but there are exceptions.
•	For example, the highly specialized sieve-tube members of the phloem are parenchyma cells.
•	Parenchyma cells perform most of the  __________  functions of the plant, synthesizing and storing various organic products.
•	For example, __________  occurs within the chloroplasts of parenchyma cells in the leaf.
•	Some parenchyma cells in the stems and roots have colorless plastids that store  __________ .
•	The fleshy tissue of most fruit is composed of parenchyma cells.
•	Most parenchyma cells retain the ability to divide and differentiate into other cell types under special conditions, such as the repair and replacement of organs after injury to the plant.
•	In the laboratory, it is possible to regenerate an entire plant from a single parenchyma cell.
•	Collenchyma cells have  __________  primary walls than parenchyma cells, though the walls are  __________  thickened.
•	Grouped into strands or cylinders, collenchyma cells help  __________  young parts of the plant shoot.
•	Young stems and petioles often have strands of collenchyma just below the  __________ , providing support without restraining growth.
•	Mature collenchyma cells are living and flexible and  __________  with the stems and leaves they support.
•	Sclerenchyma cells have thick  __________  walls usually strengthened by lignin and function as  __________  elements of the plant.
•	They are much more  __________  than collenchyma cells.
•	Unlike parenchyma and collenchyma cells, they cannot  __________ .
•	Sclerenchyma cells occur in plant regions that have stopped  __________ .
•	Many sclerenchyma cells are  __________  at functional maturity, but they produce rigid  __________  cells walls before the protoplast dies.
•	In parts of the plant that are still elongating, secondary walls are deposited in a spiral or ring pattern, enabling the cell wall to stretch like a spring as the cell grows.
•	Two types of sclerenchyma cells, fibers and sclereids, are specialized entirely for support.
•	__________  are long, slender, and tapered, and usually occur in groups.
•	Those from hemp fibers are used for making rope, and those from flax are woven into linen.
•	__________  are irregular in shape and are shorter than fibers.
•	They have very thick, lignified  __________  walls.
•	__________  impart hardness to nutshells and seed coats and the gritty texture to pear fruits.
•	The water-conducting elements of xylem, the tracheids and vessel elements, are elongated cells that are  __________  at functional maturity.
•	The thickened cell walls remain as a nonliving conduit through which  __________  can flow.
•	Both tracheids and vessels have secondary walls interrupted by  __________ , thinner regions where only primary walls are present.
•	__________  are long, thin cells with tapered ends.
•	__________  moves from cell to cell mainly through pits.
•	Because their secondary walls are hardened with  __________ , tracheids function in support as well as transport.
•	__________  __________  are generally wider, shorter, thinner walled, and less tapered than tracheids.
•	Vessel elements are aligned end to end, forming long micropipes or __________  __________ .
•	The ends are  __________ , enabling water to flow freely.
•	In the phloem, sucrose, other organic compounds, and some mineral ions move through tubes formed by chains of cells called  __________  __________ .
•	These are alive at functional maturity, although a sieve-tube member lacks a  __________ , ribosomes, and a distinct vacuole.
•	The end walls, the  __________  __________ , have pores that facilitate the flow of fluid between cells.
•	Each sieve-tube member has a nonconducting nucleated  __________  __________ , which is connected to the sieve-tube member by numerous plasmodesmata.
•	The nucleus and ribosomes of the companion cell serve both that cell and the adjacent sieve-tube member.
•	In some plants, companion cells in leaves help load  __________  into the sieve-tube members, which transport the sugars to other parts of the plant.
•	The primary growth of roots consists of the epidermis, ground tissue, and vascular tissue.
•	Water and minerals absorbed from the soil must enter through the  __________  , a single layer of cells covering the root.
•	Root  __________   greatly increase the surface area of epidermal cells.
•	Most roots have a solid core of  __________  and  __________  . The  __________   radiates from the center in two or more spokes, with  __________  developing in the wedges between the spokes.
•	In monocot roots, the vascular tissue consists of a central core of  __________   surrounded by alternating patterns of  __________   and  __________  .
•	The  __________   tissue of roots consists of parenchyma cells that fill the  __________  , the region between the vascular cylinder and the epidermis.
•	Cells within the ground tissue store  __________   and are active in the uptake of  __________   that enter the root with the soil solution.
•	The innermost layer of the cortex, the  __________  , is a cylinder one cell thick that forms a selective barrier between the  __________   and the  __________   cylinder.
•	An established root may sprout  __________   roots from the outermost layer of the vascular cylinder, the  __________  .
•	The vascular tissue of the lateral root maintains its connection to the vascular tissue of the primary root.
•	The  __________   meristem of a shoot is a dome-shaped mass of expanding and dividing cells at the terminal bud.
•	Leaves arise as leaf  __________   on the flanks of the apical meristem.
•	__________   __________   develop from islands of meristematic cells left by apical meristems at the axils of the leaf primordia.
•	Within a bud, leaf primordia are crowded close together because internodes are very short.
•	Most of the elongation of the shoot occurs by growth in length of slightly older internodes below the shoot apex.
•	This growth is due to cell  __________   and cell  __________   within the internode.
•	In some plants, including grasses, internodes continue to elongate all along the length of the shoot over a prolonged period.
•	These plants have meristematic regions called  __________   meristems at the base of each leaf.
•	This explains why grass continues to  __________   after being mowed.
•	Unlike their central position in a root, vascular tissue runs the length of a stem in strands called  __________   __________  .
•	Because the vascular system of the stem is near the surface, branches can develop with connections to the vascular tissue without having to originate from deep within the main shoot.
•	In gymnosperms and most eudicots, the vascular bundles are arranged in a ring, with  __________   inside and  __________   outside the ring.
•	The vascular bundles have  __________   facing the pith and  __________   facing the cortex.
•	In the stems of most monocots, the vascular bundles are  __________   throughout the ground tissue rather than arranged in a ring.
•	In both monocots and eudicots, the stem’s ground tissue is mostly  __________  .
•	Many stems are strengthened by  __________   just beneath the epidermis.
•	Sclerenchyma  __________   cells within vascular bundles also help support stems.
•	The leaf  __________   is composed of cells tightly locked together like pieces of a puzzle.
•	The leaf epidermis is the first line of defense against  __________   damage and  __________   organisms, and its waxy cuticle is a barrier to  __________   loss from the plant.
•	The epidermal barrier is interrupted only by the  __________  , tiny pores flanked by specialized epidermal cells called  __________   __________  .
•	Each stoma is an opening between a pair of guard cells that regulate the  __________   and  __________   of the pore.
•	The stomata regulate  __________   exchange between the surrounding air and the photosynthetic cells inside the leaf.
•	They are also the major avenues of evaporative  __________   loss from the plant—a process called transpiration.
•	The ground tissue of the leaf, the  __________  , is sandwiched between the upper and lower epidermis.
•	It consists mainly of parenchyma cells with many  __________   and specialized for photosynthesis.
•	In many eudicots, a layer or more of columnar  __________   mesophyll lies over  __________   mesophyll.
•	Carbon dioxide and oxygen circulate through the labyrinth of air spaces around the irregularly spaced cells of the spongy mesophyll.
•	The air spaces are particularly large near stomata, where  __________   exchange with the outside air occurs.
•	The vascular tissue of a  __________   is continuous with the xylem and phloem of the  __________ .
•	__________   __________  , branches of vascular bundles in the stem, pass through petioles and into leaves.
•	Vascular bundles in the leaves are called  __________  . Each vein is enclosed in a protective  __________   __________   consisting of one or more layers of parenchyma.
•	Within a leaf, veins subdivide repeatedly and branch throughout the mesophyll.
•	The xylem brings  __________   and  __________   to the photosynthetic tissues and the phloem carries  __________   and other organic products to other parts of the plant.
•	The vascular infrastructure also functions to  __________   and reinforce the shape of the leaf.
3. Secondary growth: lateral meristems add  __________   by producing secondary vascular tissue and periderm.
•	The stems and roots of most eudicots increase in girth by  __________   __________  .
•	The  __________   plant body consists of the tissues produced during this secondary growth in diameter.
•	Primary and secondary growth occur simultaneously but in different  __________  .
•	While expansion and elongation of the stem (__________   growth) occurs at the apical meristem, increases in diameter  (__________   growth) occur farther down the stem.
•	The  __________   __________   is a cylinder of meristematic cells that forms secondary vascular tissue.
•	It forms successive layers of secondary  __________  to its interior and secondary  __________  to its exterior.
•	The accumulation of this tissue over the years accounts for most of the increase in diameter of a  __________   plant.
•	The vascular cambium develops from  __________   __________   that retain the capacity to divide.
•	This meristem forms in a layer between the primary  __________  and primary  __________   of each vascular bundle and in the ground tissue  __________   the bundles.
•	The meristematic bands unite to form a continuous  __________   of dividing cells.
•	This ring of vascular cambium consists of regions of  __________   initials and  __________   initials.
•	The tapered, elongated cells of the fusiform initials form secondary xylem to the  __________   of the vascular cambium and secondary phloem to the  __________  .
•	Ray initials produce vascular  __________   that  __________   water and nutrients laterally within the woody stem and also  __________   starch and other reserves.
•	As secondary growth continues over the years, layer upon layer of secondary xylem accumulates, producing the tissue we call  __________  .
•	Wood consists mainly of  __________  , __________   __________   (in angiosperms), and __________  .
•	These cells, dead at functional maturity, have thick, __________   walls that give wood its hardness and strength.
•	In temperate regions, secondary growth in perennial plants ceases during the winter.
•	The first tracheid and vessel cells formed in the spring (early wood) have  __________   diameters and  __________   walls than cells produced later in the summer (late wood).
•	The structure of the early wood maximizes delivery of  __________   to new, expanding leaves.
•	The thick-walled cells of  __________   wood provide more physical  __________  .
•	This pattern of growth—cambium dormancy, early wood production, and late wood production—produces  __________   growth rings.
•	As a tree or woody shrub ages, the older layers of secondary xylem, known as  __________  , no longer transport water and minerals.
•	The outer layers, known as  __________  , continue to transport xylem sap.
•	Only the youngest secondary phloem, closest to the  __________   __________  , functions in sugar transport.
•	The older secondary phloem dies and is sloughed off as part of the __________  .
•	The  __________   __________   acts as a meristem for a tough, thick covering for stems and roots that replaces the epidermis.
•	Early in secondary growth, the  __________   produced by primary growth splits, dries, and falls off the stem or root.
•	It is replaced by two tissues produced by the first cork cambium, which arises in the outer  __________   of stems and in the outer layer of the  __________   of roots.
•	The first tissue, __________  , is a thin layer of parenchyma cells that forms to the interior of the cork cambium.
•	Cork cambium also produces  __________   cells, which accumulate at the cambium’s exterior.
•	Waxy material called  __________   deposited in the cell walls of cork cells before they die acts as a barrier against water loss, physical damage, and pathogens.
•	The cork plus the cork cambium form the  __________  , a protective layer that replaces the epidermis.
•	In areas called  __________  , spaces develop between the cork cells of the periderm.
•	These areas within the trunk facilitate  __________   exchange with the outside air.
•	Unlike the vascular cambium, cells of the cork cambium do not divide.
•	The thickening of a stem or root  __________   the first cork cambium, which loses its meristematic activity and differentiates into cork cells.
•	A new cork cambium forms to the  __________  , resulting in a new layer of periderm.
•	As this process continues, older layers of periderm are sloughed off.
•	This produces the cracked, peeling  __________   of many tree trunks.
•	Bark refers to all tissues external to the  __________   __________  , including secondary phloem, cork cambium, and cork.
C. Mechanisms of Plant Growth and Development
•	During plant development, a single cell, the  __________  , gives rise to a multicellular plant of particular form with functionally integrated cells, tissues, and organs.
•	An increase in mass, or  __________  , results from cell division and cell expansion.
•	The development of body form and organization is called  __________  .
•	The specialization of cells with the same set of genetic instructions to produce a diversity of cell types is called  __________  .
•	Plants have tremendous developmental  __________  .
•	Plant form, including height, branching patterns, and reproductive output, is greatly influenced by  __________   factors.
•	A broad range of morphologies can result from the same genotype as three developmental processes—growth, morphogenesis, and differentiation—transform a zygote into an adult plant.