I. Plant Structure & Growth

II.Transport in Plants

III. Plants Nutrition

IV. Plant Reproduction & Development

V. Control Systems

VI.Related Links

I. Plant Structures & Growth
	A. Plant biology reflects the mjor themes in the study of life
	-They offer scientists the chance to research genetic control of plant development because 
of their tiny genomes ( amount of DNA per cell).  It allows scientists to relate procoesses 
that occur at the molecular level,and cellular level, eith emergent properties arising from the ordered arrangement 
& interactions of component parts.  Plants also have utilized the theory of natural selsction by structurally adapting 
to their surroundings.
B. A Plant's Root & Shoot Systems
		1. Plants structure is studied on 2 levels
			a. Morphology- The study of the external structure of plants.
			b. Anatomy- The study of internal structures.
		2. Angiosperms: Flowering plants ( algae, mosses, ferns & gymnosperms).
			a. Characteristics-Most diverse & widespread. Produces flowers and fruits.
 			Divided into 2 classes.
				-Monocots: Named for their single cotyledon (seed leaf)
				-Dicots: Named for their two cotyledon.
		3. Root System - Roots anchor & absorb minerals/water, conducts h2o/nutrients 
		and stores food.
			a. Tap Root System: of dicots consists of 1 verticle root (taproot), and
 			smaller lateral roots.  It is a firm anchor & can store large amounts of food.
			b. Fibrous System: of monocots consists of a network of threadlike roots 			
                        that spread out below the surface.  Gives extensive exposure to soil water, 			
                        minerals and helps anchor plant.  Also helps to prevent soil erosion.
			c. Root Hairs : In both mono & dicots, occurs near root tips. They increase
 			surface area for H2o, and mineral absorbtion.
			d.  Adventitious: " not belonging to" Any plant part that grows in an
 			unusual location.
		4. Shoot System- Consists of vegatative shoot that produce leaves, and floral
 		shoots that produce flowers.  Includes a stem & attached leaves (vegatative
 		branch)
			a. Stems: Alternating nodes ( points at which leavv es are attached), and
 			internodes (stem segments between nodes).  axillary bud, formed between
 			each leaf & stem, which functions as an embryonic side shoot which are
 			usually dormant. 
			b. Terminal Bud: Consists of developing leaves & a series of nodes &
 			internodes.
			c. Apical Dominance: Act of inhibiting the growth of axillary buds, which
 			increases the plant's exposure to light, especially in areas of dense
 			vegetation.
		5. Leaves: Are the main photosynthetic organ & consists of a blade & stalk.
			a. Petiole: joins the leaf to a node on a stem
		           *b. Vascular arrangement, leaf shape & leaf placement on the stem are
 			characteristics used to identify and classify plants.
	C.  Plant cells Organized into 3 Major Tissue Systems (plant anatomy)
		1. Types of Plant Cells.
			a. Protoplasts: Region of cell excluding the cell wall.
			b. Parenchyma Cells : " typical plant cells" least specialized. Performs most
 			of the metabolic functions, storing organic products, and synthesizing.
 			Comprises the fleshy tissue of most fruits.	
			c. Sclerenchyma: Specialized for support 2 types
				-Fiber & Sclereids
			d. Collenchyma Cells: Help support young parts of plants by its thick
 			primary wall
			e. Tracheids & Vessel Elements : Water conducting cells of the xylem.
				-Pits: Thinner regions where only primary walls are present
				-Xylem Vessels: Long micropipes formed by vessel elements.
			f. Sieve Tube Members: Fodd conducting cells
				-Sieve Plates: have pores that facilitate the flow of fluid from cell to
 				cell along the sieve tube.
				-Companion Cell: Has a nucleus and ribosomes in which it shares
 				with other cells
		2. Three Tissue Systems of a Plants
			a. Dermal Tissue System ( Epidermis): Single layer of tightly packed cells,
 			the skin of the plant.  It protects & has specialized characteristics
 			consistant with the function of the particular organ it covers.  Covered with
 			Cuticle(waxy covering)
			b. Vascular Tissue System: Is the continuation of the xylem& phloem,
 			which functions in transport and support.
			c. Ground Tissue System: Space between the dermal and vacular systems.
 			Makes up the bulk of young plants functions include; photosynthesis,
 			storage & support.
 	D. Meristems Generate Cells for New Organs ( plant growth)
		1.Intermediate Growth
			a. Annuals: complete life cycle in a single year or less
			b. Biennial: completes its life cycle in two years or more
			c. Perennials:plants that live many years
			d. Meristems: unspecialized regions which divide to generate cells & gives
 			plants the capacity for indeterminate growth, 3 types;protoderm,
 			procambium, and ground meristem.
			e. Apical meristem: Located at the roots, they supply cells for the plant to
 			grow in length( This elongation is known as primary growth, which
 			produces the primary plant body.(root cap,zone of cell division, zone of
 			elongation, zone of maturation and quiescent center)
	

Glossary of Key Terms
vasscular bundles		ray initials
stamata				xylem rays
guard cells			phloem rays
transpiration			fusiform initials
mesophyll			phelloderm
secondary plant body		cork cells	
vascular cambium		periderm	
cork cambium			bark

II. Transport in Plants
	A. Overview of Water and Solute Transport
		-Transport occur within the plants organs, and throughout the entire plant.
		1. Cellular: solutes move across membranes by passive(diffusion) and active
 		transport(by a chemiosmotic mechanism): proton pumps store energy in the form
 		of H+ gradient across the membrane, and specific transport proteins couple the
 		diffusion of H+ to the movement of other solutes.
		2. Water potential differences: drives osmotic movement of water into and out of
 		plant cilles. Solutes lower water potential, pressure increases water potential.
  		Hypertonic situations lower water potential of plant, but equilibrium will
 		eventually be reached ( turgid cell)
		3. Lateral transport of solutes and water can occur via the symplast ( cytoplasmic
 		continuum) or apoplast 	(continuum of cell walls) or by a combination of
 		these systems.
		4. Long Distance transport
			a. sap: in the xylem and phloem occurs by bulk flow, the pressure-driven
 			movement of a fluid.
	B.  Roots Absorb Water and Minerals from Soil.
		1.  H2o and minerals gain acces to roots through epidermal cells and root
 		hairs.Cell walls are hydrophiliclic, in contact with the root cortex, and provide
 		acess to the apoplastic pathway across the cortex.  Minerals are removed from the
 		apoplast by cortical cell, which later enter the symplastic pathway.
		2. Casparian Strip; of the endodermis blocks apoplastic entry of H2O&
 		minerals into the stele.  Endodermis helps regulate mineral intake and composition
 		of the xylem sap.
	C. Xylem Sap depends on transpiration & physical properties of H2O.
		1. Upward flow in the xylem supplies minerals to shoots and replaces H2O lost by
 		transpration.
		2.  Transipration/Cohesion/tension/  Mechanism transports xylem sap.  Surface
 		tension  of the
 	mesophyll cells produced by the evaporative water loss during
 		transpiration. This tension in turn ( negative pressure), causes H2O to move by
 		bulk flow out of the xylem vessels.  The cohesion of H2O due to hydrogen bonds
 		relays the transpiration pull on the xylem all the way down to the roots.
	D. Function of Guard Cells During Transpiration and Photosynthesis
		1. Stomata balance the loss associated with gas exchange and water loss.
			a. Closing the stomata by changes in the tugor pressure in guard cells,due
 			to potassium ions, plants regulate photosynthesis and transpiration.
			b.Guard Cellsusually open at dawn (due to CO2), because of its inherited
 			circadian rhythm, and ion movements triggered by light-detecting pigments.
			c. When Carbon Dioxide diffuses into the leaf, water is loss, so plants with
 			lower transpiration-to-photosynthesis rates due well in arid climates.
			d. Xerophytic plants in dry habitats have leaves equipted with
 			morphological/ physiological adaptations that reduce transpiration.
			e. CAM plants have a reversed stomata rhthym to conserve water;stomata
 			open at night.
	E. Functions of the Bulk-Flow Mechanism
		1. It translocates phloem sap from sugar sources to sugar sinks.
			a. Translocation: the process of transporting photosynthetically produced
 			food throughout the entire body of the plant in the phloem(usually
 			sucrose).
		2. Sieve tubes of phloem carry food from a sugar source to the sugar sink; soure-
		an organ that produces 	sugar by photosynthesis or the break down of starch.
 		sugar sink- consumes/stores sugar.


Glossary of Key Terms
Transport proteins		bulk-flow		transpiration
carrier proteins			tension			root presure
selective channels		Tugor pressure		guttation
proton pump			tonoplasts		cohesion/adhesion
cotransport			symplast		circadian rhythms
chemiomosis			plasmodesmata		translocation
osmosis			apoplast		sugar source & sugar sink
Water potential			endodermis		transfer cells
megapascals			casparian strip

III. Plant Nutrition
Key Terms
					Essential Nutrient		sustainable agriculture
					macronutrients			nitrogen-fixing bacteria
					micronutrients			nitrogen fixation
					topsoil				nitrogenase
					horizons			backroids
					hydroponic culture		mycorrhizae
					humus				carion exchange
	A. the 17 Essential Nutrient of Plants
		1.Because plants are photosynthetic autotrophs, they produce their own organic
 		compounds, but required in organic nutrients(carbon dioxide, water and minerals).
			a. water provides a source of hydrogen, and carbon dioxide is incorporated
 			into the plant as carbohydrates.  minerals are selectively absorbed by the
 			roots.
			b. Plants require 9 elements ( the macronutrients) in large amounts.(carbon,
 			oxygen, hydrogen, nitrogen, sulfur, phosphorus, potassium, calcium, and
 			magnesium.)
			c. the 8 micronutrients are needed in small amounts and sre used as
 			cofactors in enzymatic reactions(chlorine, iron, boron, manganese, zinc,
 			molybdenum, nickel).
			d. mineral deficiencies reflect the composition of the soil& cause various
 			symptoms that depend on the mobility of the nutrient and the nutrient of the plant.
	B. Soil Characteristics
		1. Texture: depends of size ofparticles, most fertile soil consists of loams, which
 		contain fine particles and retain large amounts of water/minerals, and coarse
 		particles that provide drainage. 
		2. Living organisims of the soil- help produce humus( the decomposing material
 		that improves the texture & mineral content of the soil.
		3. Cation exchange-When clay particles that are negatively charged attract water
 		and cations, releases acids, the roots obtain solutes.
		4. Soil Conservation- Agriculture depletes mineral reseves of soil, and uses the
 		water supply, which encourages erosion.
	C. Soil Bacteria
		1. Nitrogen is essential for plant growth and crop yeilds and is an important
 		ingredient of proteins and nucleic acids.
		2. Bacteria in soil provide plants with the necessary amounts of nitrogen in forms
 		they can use(nitrogen-fixing bacteria).
			a. the bacteria possess nitrogenase ( an enzyme that converts atmospheric
 			nitrogen to ammonia, which is then converted in the soil into nitrate
  		'ammonium', and is absorbed by the plant.
			b. legume roots have nodular swellings that house notrogen-fixing
 			bacteria(they coevolved with the plants).
	D. Predation & symbiosis
		1.Parasitic plants_ either supplement their photosynthetic nutrition or give up
 		photosynthesis entirely by tapping into a host plant.
		2. Carnivorous plants- obtain nitrogen 7 minerals by killing and eating insects
		3. Mycorrhizae- (mutaulistic ) associations between roots and fungi, it helps the
 		plant by enhancing mineral nutrition, water absorbtion, and is resistant to
 		pathogens.

IV.Plant Reproduction & Development
Key Terms
			alternation of generations	sporophyte		gametophyte
			sepals				petals			stamens
			carpels				ovules			complete flowers
			incomplete flowers		perfect flower		imperfect flower
			monoecious			dioecious		microspores		
			megaspores			embryo sac		pollination
			self-incompatible		endosperm		double fertilization
			seed coat			hypocotyl		radicle
			epicotyl				scutellum		coleorohiza
			coleoptile			fruit			periarp
			simple fruit			aggregate gruit		multiple 			fruit		                        imbibition          	vegetative 			reproduction
			apomixis			callus			stock
			scion				protoplast fusion	monoculture
			development			growth			morphogenesis
			perprophase band		pattern formation	positional information
			organ-identity genes		cellular differentiation	stigma
			anther				filament		style
			ovule				ovary			receptacle
	A. Overview of Sporophytes and Gametophytes life cycles
		1. Alternating haploid and diploid generations take turns producuing eachother.
		Diploids are known as sporophyts, which produces haploid spores by meiosis, the
 		divided spore then gives rise to a multicellular male or female Gametophyte- the
 		haploid generation.  
		2. Dominant stage is the diploid sporophyt, which spores develop inside the flower
 		into tiny, haploid gametophyts; the male pollen grain and the female embryo sac.
	B. Male and female gametophytes develop within the anthers and ovaries, respectively
		1. Pollen develops from mocrospores inside the sporangia of the anther
		2. Within the ovule, a haploid megaspore divides by Mitosis, and forms the embryo
 		sac, the female gametophyte.
	C Pollination brings female and male gametophytes together.
		1. Fertilization is followed by pollenation, the placing of pollen on the stigma
 		on the carpel.
		2.Pollen grain produces a pollen tube that extends down the embryo style towards
 		the embryo sac.  Two sperm are released and effect a double fertilization, resulting
 		in a diploid zygote and a triploid endosperm.
	D. Ovule develops into a seed containing a sporophyts embryo and a supply of nutrients.
		1. Zygote gives rise to embryo with apical meristems and one or two cotyledons
		2. Mitotic division of the triploid endosperm gives rise to a multicellular mass that
 		feeds the embryo.
	E, Ovary develops into a fruit adapted for seed dispersal
		1.Fruit- is a mature ovary that protects the enclosed seeds and aids in their
 		dispersal via wind and animals.
		2. Evolutionary adaptations in the germination process
			a. Germination begins when seeds imbile water, it expands the seed,
 			ruptures its coat, and triggers metabgolic changesto resume growth.
			b. the embryonic root, or radicle emerges first, and then the embryonic 
			shoot breaks through the soil surface.
	F. Many plants clone themselves through asexual reproduction.
		1. Asexual reproduction (cloning) is the production of genetically identical
 		offspring from a single parent.
		2. Fragmentation of parent can reform whole plants, which demonstrates the
 		versatility and latent potential of meristematic and parenchymal tissues.
		3. In Horticulture/ agriculture, plants  can be asexually propagated from isolated
 		leaves, pieces of specialized storage stems or shoots.
		4. Labs can clone large numbers of plants by culturing small explants of single
 		parenchyma cells.
		5. Both Sexual and asexual reproduction offer advantages in different situations.
 		Asexual; enables successful clones to spread. Sexual; generates genetic variation
 		that make adaptation possible.
	G. Growth, morphogenesis, and differentiation produce the plant body.
		1. During grwoth the planes of cell division and expansions determine the shape of
 		each organ.
		2. The cytoskeleton sets the plane of cell division by forming a preprophase band.
		It also controls the direction of cell expansion by determinging the orientation of
 		cellulose microfibrils that are deposited in the developing wall.
		3. Cellular differentiation depends on the control of gene expression.
			a. the basic challenge of cellular differentiation is to explain how cells with
 			matching genomes diverge into cells of diverse structure and function.
	H. Mechanisms of pattern formation determine the location and tissue organization of
 	plant organs.
		1. Pattern formations, the emergence of organs and tissues in specific locations,
 		depends on the ability of developing cells to detect and respond to positional
 		stimuli.
		2. Clonal analysis of shoot tips suggest that a cell's developmenal fate is
 		determined by its final location within a primordial organ.
		3. By studying organ identity genes that cause floral organs to develop in the
 		wrong locations, plant biologists are investigating the genetic basis of pattern
 		formation.

Other Areas of Plant Research
	*Comtrol Sysytems in Plants
		-Plants grow towards light, this discovery led to the detection of hormones in
 		plants.
		-Plant hormones help coordinate growth, development, and responses to
 		environmental stimuli.
		- Tropisms orient the growth of plant organs toward or away from stimuli.
		-Biological clocks control circadian rhythms in plants and other eukaryotes.
		-Turgor movements are relatively rapid, reversible plant responses.
		- Photoperiodism synchronizes many plant responses to changes in seasons.
		-Phytochrome functions as a photoreceptor in many plant responses to light and
 		photoperiod.
		-Control systems enable plants to cope with environmental stress.
		-Signal-transduction pathways mediate the responses to environmental and
 		hormonal stimuli.