Cannot transport water through plants

Example: Mosses

• one leaf
• one cotyledon
• veins parallel
• vascular tissue scattered
• fibrous root (no main root)
• example: grass

• two leaves
• two cotyledons
• veins netlike
• vascular tissue arranged in a ring
• taproot (main root)
• example: trees

Like multicellular animals--

have organs composed of different tissues composed of different cells

1. Roots
2. Stems
3. Leaves

• multicellular organ
• anchors plant to soil
• absorbs minerals & water (may also store carbs)
• many have taproot system (primary root-eudicots)
• seedless vascular plants & most monocots have no main root (many small roots grow from stem--form lateral roots--result = fibrous system)

At root tips

Large number of root hairs INCREASE surface area to allow more absorption of water and minerals

• Prop roots- provide support and anchorage (for plants like corn that are top heavy)
• Storage roots- store water and nutrients or absorb oxygen from air (store carbs like sweet potatoes)
• "Strangling" aerial roots
• Buttress roots- huge and thick
• Pneumatophores- extend above water to get oxygen

Alternating system of nodes (where leaves are attached) & internodes (stem segments between nodes)

• Axillary bud- structure that can form lateral shoot (branch) LOCATED: upper angle (axil) formed by each leaf and the stem
• Apical bud- elongation concentrated (found at shoot tip). Produces chemical to keep Axillary bud in check

Inhibition of axillary buds by an apical bud

*brings closer to sunlight

• food storage
• asexual reproduction
• storage leaves, stem, roots --- bulbs
• node, rhizome, root --- rhizomes
• tubers- tissue that is always growing
• stolons- strawberries

• main photosynthetic organ
• most consist of blade & stalk (petiole)
• leaf shape- simple, compound, or doubly compound

monocots and eudicots differ in arrangement of veins

1. Dermal
2. Vascular
3. Ground

Plants outer protective covering

• 1st line of defense against physical damage, pathogens, and water loss
• nonwoody plants; single tissue layer--epidermis
• leaves & most stems; waxy coating on epidermal surface--cuticle
• woody plants; protective tissue = periderm (replaces epidermis in older regions of stem and roots

long-distance transport of materials between root & shoot systems (leaves)

• xylem- conducts water & dissolved minerals from roots to shoots (1 way transport system)
• phloem- transports sugars to roots & growth sites; developing leaves & fruits (bi-directional movement)
• composed of a variety of tissue cells (living-phloem; nonliving-xylem)

All of the vascular tissue of a stem or root

• in angiosperms; solid central vascular cylinder
• in stems & leaves; divided into vascular bundles, strands of xylem & phloem

tissues that are neither dermal or vascular

• includes cells specialized for storage, photosynthesis, and transport

Plants characterized by cellular differentiation- the specialization of cells in structure & function

• parenchyma- most flexible; where metabolic processes take place
• collenchyma- provides support
• sclerenchyma- provides support
• water conducting cells of xylem- transport water; absorb minerals
• sugar conducting cells of phloem- transfer carbs to other parts of plant

• parenchyma- thin cell walls
• collenchyma- living;support in youngdeveloping plants
• sclerenchyma- dead; provides structure 
• water conducting(xylem)- 2 different types of cells, both dead; pits where water can move- hollow tube that functions in water movement
• sugar conducting(phloem)- 2 different types of cells, both living; all organelles gone, companion has all organelles that sieve tube doesnt

Perpetually embryonic tissue

• adult & juvenille cells in same plant; never ending growth

located at tips of roots and shoots; allow plant to grow in length

Also called primary growth

Woody plants grow in girth in parts of stems and roots that no longer grow in length

This is because of lateral meristems (vascular cambium-adds secondary xylem and secondary phloem, and cork cambium- tougher periderm)

Root tip is covered by a root cap, which protects the apical meristem as the root pushes through soil

-secrete slimy substance to penetrate soil easier

Just behind the root tip, in three zones of cells:

1. zone of cell division
2. zone of elongation
3. zone of maturation

The epidermis, ground tissue, and vascular tissue

• in most roots, stele is a vascular cylinder
• ground tissue fills cortex (region between vascular cylinder and epidermis)
• innermost layer of cortex is called the endodermis

• in gymnosperms and most eudicots, the vascular tissue consists of vascular bundles arranged in a ring
• in most monocot stems, vascular bundles are scattered throughout ground tissue

• the epidermis in leaves is interrupted by stomata (spores), which allow CO2 exchange between the air and the photosynthetic cells in a leaf
• ground tissue is sandwiched between upper and lower epidermis
• vascular tissue of each leaf is continuous with the vascualr tissue of the stem
• increase size of leaf to increase photosynthesis

Growing in width as well as length

primary growth as already taken place and no longer in effect

The secondary plant body consists of tissues produced by the vascular cambium and cork cambium

the plane and symmetry of cell division are important determinants of a plants form

-single file vs cube forms

The plane in which a cell divides is determined during late interphase

-the "imprint" consists of an ordered array of actin microfilaments that remain after the preprophase band of microtubes disperse

Water uptake accounts for about 90% of plant cell expansion (most packaged in large central vacuole)

• in a growing plant, enzymes weaken the cross-links in the cell wall allowing it to expand as water diffuses into the vacuole
• cellulose microfibrils control the direction of expansion

The development of specific structures in specific locations; determined by positional information (signals indicating to each cell its location)

*example = polarity

Structural or chemical differences at opposite ends of an organism

*establishment of this is a crucial first step in plants morphogenesis

Cells of a developing organism synthesize different proteins and diverge in structure and function even though they have a common genome

-depends on positional information

-affected by homeotic genes

developmental changes--

developing from a juvenile phase to an adult phase

*the most obvious morphological changes occur in leaf size and shape

• flower formation involves a phase change from vegetative growth to reproductive growth
• triggered by combo of environ cues & internal signals
• transition from vegetative growth to flowering is associated with the switching-on of floral meristem identity genese
• organ identity genes regulate development of foral pattern

involved differentiation into roots and shoots

vascular tissue transports nutrients in a plant; may even occur over long distances

1. transport of water & solutes by individual cells, such as root hairs
2. short-distance transport of substances from cell to cell at the levels of tissues & organs
3. long-distance transport with xylem & phloem at the level of the whole plant

• selectively permeable
• controls movement of solutes into & out of cell

• diffusion of a solute across a membrane down its electrochemical gradient
• no metabolic energy involved

• the pumping of a solute against its electrochemical gradient
• metabolic energy is expended
• USUALLY IN THE FORM OF ATP
• the most important transport proteins are proton pumps

• the combined effects of solute concentration and physical pressure are incorporated into a quantity
• determines the direction of movement of water
• water flows from regions of higher water potential to regions of lower water potential; if there is no barrier
• water potential refers to water's potential energy (ability of water to do work when it moves from region of higher to lower water potential)

• the addition of solutes reduces water potential
• physical pressure increases water potential
• negative pressure decreases water potential

Affects water loss & uptake by plant cells

• if a flaccid cell is placed in an environment with a higher solute concentration- cell will lose water & become plasmolyzed
• if same cell is placed in solution with lower solute concentration- cell will gain water & become turgid

Cell compartments (structure of plant cells)

1. Plasmodesma
2. Plasma membrane
3. Vaculoar membrane (tonoplast)

1. Transmembrane route (out of one cell, across a cell wall, and into another cell)
2. Symplastic route (via the continuum of cytosol)
3. Apoplastic route (via the cells walls & extracellular spaces)

water and mineral salts from soil enter the plant through the epidermis of roots and ultimately flow to shoot system; most absorption occurs at root hairs

After soil solution enters the roots, the extensive surface area of cortical cell membranes enhances uptake of water and selected minerals

• planst lose an enormous amount of water through transpiration-loss of water from leaves & other aerial parts of the plant
• water vapor in airspaces of leaf diffuses down water potential gradient & exits leaf via stomata
• transpiration produces neg pressure (tension) in leaf, which exerts a pulling force in the xylem, pulling water into the leaf

Which of the following are produced by the vascular cambrium?

A. cork

B. secondary pholem

C. secondary xylem

D. periderm

E. both B & C

• transmitted all the way from the leaves to the root tips and even into the soil solution
• facilitated by the cohesion & adhesion of water molecules
• movement of xylem sap against gravity is maintained by the transpiration-cohesion-tension mechanism

• night (transpiration low) root cells continue pumping mineral ions into xylem of vascular cylinder--lowering the water potential 
• water flows from root cortex; generating root pressure
• root pressure sometimes results in guttation

• leaves have broad surface areas & high suface to volume ratios
• ^^ increase photosynthesis but increase water loss through stomata
• about 90% of the water a plant loses escapes through stomata

1. Light stimulates guard cells to accumulate K+ and become turgid (triggered by illumination of blue-light receptors in plasma membrane of guard cells
2. Stoma also open in response to CO2 within leaves air spaces
3. The internal "clock" in the guard cells ensures daily rhythm of opening and closing

• environmental stresses (droughts) can cause stoma to close during the daytime by loss of turgor
• abscisic acid (plant hormone) produced in the roots & leaves in response to water deficiency signals guard cells to close

• phloem sap is an aqueous solution that is mostly sucrose
• travels from a sugar source to a sugar sink

• spores are dominant
• angiosperm gametophytes are the most reduced of all plants, consisting of only a few cells
• key derived traits of angiosperm life cycle: 'three Fs' - flowers, double fertilization, and fruits

1. Stamen (anther & filament)
2. Petals
3. Sepals
4. Carpels (stigma, style, ovary)

All attached to a part of the stem-- receptacle 

1. Microsporocyte (2n) --undergoes meiosis
2. Microspores (4 1n cells) --produces 4 daughter cells
3. Each of 4 microspores --mitosis; duplication
4. MALE GAMETOPHYTE (pollen grain) --multicellular; [nucleus of] tube cell = larger cell & generative cell (will form 2 sperm) inside

1. Ovule; megasporangium(n), megasporocyte(2n), integuments-provide protection, micropyle
2. [only 1] Surviving megaspore-- each daughter cell will be 1n; end up with 8 cells (mitosis)
3. FEMALE GAMETOPHYTE (embryo sac):

• 3 antipodal cells
• 2 polar nuclei (function unknown)
• 1 egg
• 2 synergids (release chemical to attract)

The transfer of pollen from an anther to a stigma

1. after landing on receptive stigma, pollen grain produces a pollen tube that extends between the cells of the style toward the ovary
2. the pollen tube then discharges two sperm into embryo sac
3. one sperm fertilizes the egg, and the other combines with the polar nuclei, giving rise to the food-storing endosperm

ensures the endosperm will develop only in ovules where the egg has been fertilized; 

after undergoes double fertilization, each ovule develops into a seed-- the ovary develops into a fruit enclosing the seed(s)

The first mitotic division of the zygote is transverse, splitting the fertilized egg into a basal cell and a terminal cell

• terminal cell forms cotyledons
• eudicot with 2 cotyledons is heart shaped
• only one cotyledon develops in monocots

• during fruit development the ovary wall becomes the pericarp (the thickened wall of the fruit)
• other parts of the flower usually wither and are shed
• only thing left is developing