BZ 120: Week 9

What is a companion cell? (What is it a "companion" to?) What are it functions, and how are those functions related to its structure?

-"companion" next to smt -controls activity of stm, including loading and unloading of sucrose through plasmodesmata -Has nucleus and is alive

What is collenchyma tissue? In what ways are collenchyma cells similar to parenchyma cells, and in what ways are they different? What are the typical features of collenchyma cells? Are they alive or dead at maturity? What type of cell walls do they have? What are the typical functions of collenchyma cells? How does their structure relate to their function? Where are they typically found? What's a common example of collenchyma cells?

-Collenchyma: Simple, only one cell like elongated parenchyma, but with thick regions in primary wall. Usually in bundles; provides mechanical support to young parts (still elongating), like celery strings. Alive when they are functional.

What is xylem tissue? Is it simple or complex? What are its major functions?

-Complex; moves water and minerals, includes wood "xylon"

What is parenchyma tissue? Is it simple or complex? Where is it found? What are the typical features of parenchyma cells? Are they alive or dead at maturity? What type of cell walls do they have? What are the typical functions of parenchyma cells? How does their structure relate to their function?

-Parenchyma: Typical plant cell/Side filler. Occur in stems, leafs, and roots. Simple, with only one cell, make up majority of ground tissue. Living at maturity, primary wall, various shapes. Metabolically active (photosyn, resp, food storage), retains capacity for cell division (can go backwards developmentally=dedifferentiation). Thin primary cell walls, and different plastids.

What is epidermis tissue? Where is it found, and what are its functions? What kinds of cells does it contain? What is the cuticle, and what's its functional significance? What are guard cells? What is a stoma, and how does it function? You should understand and be able to explain the mechanism of stomatal opening and closing. When are stomata generally open in most plants? What about in CAM plants? What are root hairs, and where are they found? What is their functional significance?

-Part of the Dermal TS -Epidermis: Original outer layer (skin) on stems, roots and leaves -In leaves and stems can have waxy layer (cuticle) to reduce water loss. Includes guard cells and stoma between them -In roots, epidermal cells have "root hair" extensions that greatly increase absorptive surface area -Stoma: any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width that allows movement of gases in and out of the intercellular spaces -Stoma opens when guard cell turgor pressure increases because they cant bend as easily, and close when it decreases. -In most plants, stomata open during the day for gas exchange (opposite in CAM plants)

What is periderm tissue? Does it occur in all plants? Where is it generally found, and how does it differ from epidermis tissue?

-Periderm tissue: Only found in woody stems and roots; replaces epidermis since it has no meristem. -Can grow in size -Complex tissue with more than one type of cell -Has three parts

What is sclerenchyma tissue? How does it differ from parenchyma & collenchyma? What are its typical functions? What is a fiber? A sclereid? (In what ways are they similar, and how do they differ?)

-Sclerenchyma: Simple, dead at maturity* w/ thick lignified secondary wall (support, protection). 2 kinds based on shape -fiber: elongated, tapered cell for support in bundles; sometimes in vascular -scleroid: not elongated ("stone" cells in pears)

What is meant by the term "tracheary elements"? What are the 2 tracheary elements? In what ways are they similar to one another, and how do they differ? In what plants are they found? (You should be able to describe the structure and function of tracheids and vessel members, and the relationship between vessel members and vessels.) How does water move from one tracheid to another? From one vessel member to another? What are pits, and why are they important in this context?

-Tracheary elements: dead cells that act as pipes to move water 1) tracheid (more primitive): long, thin tapered tubes secondary wall,connected by pits (holes in secondary wall). Only tracheary element in more primitive pl., incl. gymnosperms 2) Vessel member/element - fatter, barrel-shaped cells, connected end to end to form a polyvessel w/ larger openings at connections Only in angiosperms/flowering plants.More efficient than tracheids in moving water (fatter pipes)

You should be able to explain the relationship between the periderm, cork cambium, phelloderm & cork cells.

1.) Cork cambium: A lateral meristem. Forms in outer cortex; divides and produces new cells to outside and inside. -Outside cells that are produced die, but they secrete a substance that is waxy=cork 2.) Cork cells: Produced by cc to the outside. Cells die and form outer protective layer to replace epidermis (which is sloughed off to the outside). 3.) Phelloderm cells: Produced by cc to the inside. Cells are like parenchyma cells. -Since periderm contains lateral meristem (cc), it can increase in girth as woody stem or root growths.

What are the 3 tissue systems that make up the body of a plant, and what general functions are associated with each? What tissues belong to each tissue system? What are the general functions of the various tissue systems and their constituent tissues?

1.) Dermal TS: "skin"-protection, water conservation, gas exchange, water absorption -Epidermis Tissue: Original outer covering. Large surface area to exchange materials -Periderm Tissue: Replaces epidermis in woody stems and roots, and contains a meristem that allows for growth 2.) Vascular TS: "plumbing," movement of materials in vascular veins/bundles -Xylem: Used to move water and minerals among parts of the plants, acts as a pipe. -Phloem: Moves food (sucrose) 3.) Ground TS: Filler tissue, everything else, "basic" tissue -Parenchyma-Collenchyma-Sclerenchyma

What is a sieve tube member/element? Is it alive or dead when it is functional? (In what ways is it unusual in this regard?) What type of cell wall does it have, and what special features does its wall contain? (What are sieve areas and sieve plates? How are they formed and what's their functional significance?)

1.) Sieve tube member/ element: elongated, living cell, through which sucrose sol'n. moves. -has "sieve areas" in primary wall, and enlarged plasmodesmata in end walls -join end to end to form a sieve tube member; controls activity of stm, with cytopl. continuous throughout the plasmodesmata. -Although alive, nucleus and most organelles break down, so contents is cytopl. ground substance with sucrose dissolved in it.

What additional cell types can occur in phloem tissue, and what are their functions?

3.) Parenchyma: Moves water and food sideways, e.g. in "rays" of wood 4.) Fibers: For support

What additional cell types can occur in xylem tissue, and what are their functions?

3.) Parenchyma: Moves water and food sideways, e.g. in "rays" of wood 4.) Fibers: For support

What is meant by plant tissue systems, tissues, and cell types? (What does each of these terms mean, and how are they related?)

Cells work together in the form of tissues, and groups of tissues makeup a tissue system.

What is phloem tissue? Is it simple or complex? What is its major function?

Complex, moves food (sucrose) from one part of the plant to another. Contains up to 4 cells

Where are the 3 tissue systems found within a typical stem, root, and leaf? What are the different regions of ground tissues called in stems, roots, and leaves? (What are the pith, cortex, pith rays, and mesophyll? What are the distinguishing features of each of these?)

Regions with ground tissues: -Cortex: the outermost layer of the stem or root of a plant, bounded on the outside by the epidermis and on the inside by the endodermis. Composed mostly of differentiated cells, usually large thin-walled parenchyma cells of the ground tissue system. -Pith: is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. The pith is encircled by a ring of xylem; the xylem, in turn, is encircled by a ring of phloem -Pith ray: Formations of primarily parenchyma cells. Allow the radial transport of sap -Mesophyll: the inner tissue (parenchyma) of a leaf, containing many chloroplasts. * See Figure

What's the difference between a simple tissue and a complex tissue? What are some examples of each?

Simple: One cell. (Collenchyma, Parenchyma, Sclerenchyma) Complex: More than one cell. (Xylem/Phloem)