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General Biology

by: Floy Quitzon III

General Biology BIOL 1120

Floy Quitzon III
GPA 3.63

George Benz

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George Benz
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This 67 page Class Notes was uploaded by Floy Quitzon III on Wednesday September 23, 2015. The Class Notes belongs to BIOL 1120 at Middle Tennessee State University taught by George Benz in Fall. Since its upload, it has received 29 views. For similar materials see /class/213216/biol-1120-middle-tennessee-state-university in Biology at Middle Tennessee State University.


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Date Created: 09/23/15
Overview of O Animal Dwersu ry Note all kingdoms are not shown on this figure due to space constraints 739 71IT R3911 Firmicutes 4 Spirochaetes 1 4 Actinobacteria Chlamydiae Cyanobacteria 1 liProteobacteria 4 eProteobacteria aProteobacteria w iProteobacteria y Proteobacteria fiUMAIll AilCllilEl l Korarchaeota Aerapyrum Sulfolobus Thermoplasma Archaeoglobus Pyrococcus Methanococcus Diplomonads Slime molds Animals 4 Fungi 4 Fled algae Green algae Land plants 439 Foraminifera Oomycetes Brown algae Diatoms Ciliates Dinoflagellates Apicomplexa CC 2011 Peavson Education Inc Animals fungi and 39 plants are small branch tips on the tree of life Prokaryotes Eukaryotes 393 n n o h L h n w n U n O o 3 n r n 393 to n gt 3 o c 3 g o h CD in 3 n n n n c n 3 n n U n g n CI IO Uf ANIMALIA Porifera Fungi Chow onlagexlaics Cnidaria ANIMALIA d I 39 Ctenophora I MulticelIularin Acoelomorpha JPHJTRUSHDZUA 5 9 BIIateral symmelrv 39 Rotifera Loss 0 coelom T f 4 Platyhelminthes Segmentation 39Annelida I Bilateral symmetry ProtosIome pi Mauuska development SBWOLSOIOHd VIH31V1IEI Nematoda H COelom cephalizatiun CNS V39 AnhYOPOda Segmentatmn Radialsymmetry I Echinodermata V in a u s Chordata sawmsouaman I Segmentation 53 20H Pearson Educaliun Inc TABLE 321 An Overview of Major Animal Phyla Group and Phylum Nonbilaterian groups Porifera Placozoa Cnidaria Ctenophora Acoeiomorpha O 2011 Pearson Educauon Inc Common Name Estimated Number or Example Taxa 39 of Species 7000 Placozoans 1 10000 Sponges Jelly sh corals anemones hydroids sea fans Comb Jellies Acoelomate worms TABLE 321 An Overview of Major Animal Phyla Group and Phylum Deuterostomes Echinodermata Xenoturbellida Hemichordata Chordata C 201i Pearson Education Inc Common Name Estimated Number or Example Taxa 39 of Species Echinoderms sea stars sea urchins sea cucumbers 7000 Xenoturbillidans Acorn worms Chordates tunicates lancelets sharks bony fish amphibians reptiles mammals TABLE 321 An Overview of Major Animal Phyla Estimated Number of Species Common Name or ExampleTaxa Group and Phylum Protostomes lacks typical protostome development Chaetognatha Arrow Worms Protostomes Lophotrochozoa Roliiera Roiifers Platyhelminthes Flatworms Nemertea Ribbon worms Gastrotricha Gastrotrichs Acanthocephala Acanthocephalans Entoprocta Entoprocts kamptozoans Gnathosiomulida Gnathostomulids Annelida Molluska Segmented worms Mollusks clams snails octopuses Phoronida Horseshoe worms Bryozoa Bryozoa ectoprocis moss animals Brachiopoda Brachiopods lamp shells Protostomes Ecdysozoa Nematoda Roundworms Kinorhyncha Kinorhynchs Nematomorpha Hairworms Priapula Priapulans 16 Velvet worms 110 Water bears 800 1100000 Onychophora Tardigrada Arthropoda Arthropods spiders insects crustaceans CC 20 P661150quot Education Incv F Major protostome phyla Arthropoda Nematoda Mollusca Platyhelminthes Annelida Other invertebrates by fi l ater v inzg i iood39 from wafer air Or a substrate moi39s r sand 1 SUSPENSION FEEDERS quot39 39 W3terquot 39 in Bacteriaarchaea algae organic debns 2 DEPOSIT FEEDERS Earthworms Annelida eat their way through soil I I Figure 3115 Biologlul Sdenze 21 ID 2005 Pea son Pren Ice Hill In Deposit feeders feed by ingesting nutrient rich deposits such as mud or dirt which contains living organisms and other organic matter that can be digested as food as the deposits pass through the animal39s digestive tract 39 3 HERBIVORES a SnaiMollusca feed on primary produceras as algae or plants Radula sci5 In Moth Arthropodai r K Mandibles chew d Horse Chordata Molars grind o 4 PREDATORS Predators seleCTlveIY 0 Many frogs Chordata sit and wait for prey prey on other organisms and even other predators in some instances Imagexl C Bemo A Gangland shark swallowing c ringed scal fighgd 31m m v f rred ro as 31 at pasf some d gree of 7 Ir39le39itessar39ily causa quotf Bilateria Acoelomates Pseudocoelomates Coelomates Protostomes Deuterostomes O 9quot 0 Kqb 9 O o 6quot 6 V 1 9 o 0 o 396 oz 0 a 0 Q C x 9 6 lt9 9 we ltv 9 6 66 99 it 639 39 Q 3 kquot Q Rodid 5 met Segmentation 39 in ammen tahon Deuterostome development Coelom quot Pseudocoelom Profosfome development L riplobklasfyoriginofmsodetnr I 1 Imam symmetry an cap a Izallon Radial symmetry Tissues Diploblusfy ectoderm and endoderm Multicellulurity a Choanoflagellates are sessile b Sponges are multicellular sessile protists some are colonial animals a Water current out of sponge l f 39 Choano agellate s bnge feeding Eelli C9quot choanqcytg quot K Fon 39 particles 39 Wate current 39 39 39 Multiple planes of symmetry a Asymmetry b Radial s mmetr No plane of symmetry c Bilateral symmetry 3 3 Single plane a of symmetry I 9 I Cl C lt Lizard Posterior Anterior f f Ventral a Acoelomates have no body cavity Skin No coelom from eCtOdel39m quot Muscles organs from mesoderm Gut from endoderm b Pseudocoelomates have a body cavity partially lined with mesoderm Skin 7 Pseudocoe39om from ectoderm Muscles organs V from mesoderm Gut from endoderm H Coelomates have a body cavity completely lined with mesoderm Coelom 5km from ectoderm Muscles organs a from mesoderm Gut from endoderm Dorsal blood lvessel Earthworm open closed circulation circulation Insect and earthworm as examples of animals with an open insect vs a closed earthworm circulatory system Pa rhways of Early Coeloma re Developmen r Pr39o rosfome and deuteros rome lineages are Thought To have diverged many millions of years ago possibly almost 600 million years ago and pr39o ros rome development is considered less derived Than deuterosfome development Cleavage zygote undergoes rapid divisions eventually forming a ball of cells PROTOSTOMES DEUTE ROSTOMES u u lt g L l t 4 ll m 2 3 K u Radial g 8cell Spiral stage cleavage L cleavage at Gastrulation ball of cells formed by cleavage invaginates to form gut and embryonic tissue layers Longitudinal Longitudinal section Mouth section quot becomes Anus anus Protostome Deuterostome Coelom formation body cavity lined with mesoderm develops PROTOSTOMES DEUTEROSTOMES Mesoderm Mesoderm Block of solid Mesoderm pockets mesoderm splits pinch off of gut to form coelom to form coelom x CCCC13UZJ 3 M Cross section Cross section M Annelida Arthropoda V V 1 39 Iquot quotquotv d J F v llquot A ry 39rrrr r Y Q r F N39r g 394 r V w a k MN I P Y Hnnppri k D y39 3339 quot 39 L 0quot w A Chrdata v r t r 7 1 4 39 39 o r t I x 39 1 m l I v 1 5 a s 5 s 15 l v 39 l u The of vertebrates are a classic examplle All quadrupeds amphibians reptiles birds and mammals inherited limbs from a common ancestor a fish Thus it s not surprising that the limbs of vertebrates share some distinctive qualities That said it is also obvious that as vertebrates evolved specializations to the limbs occurred such that the limbs of all vertebrates although homologous are not identical Note that the forelimbs of birds bats andquot pterodactyls are homologous all inherited from a common anCest or but that the use of thefore li mb asa wing is not that is to say that the wings of birds bats and pterodactyls each evolVed independently as evident in both the form of the structures as well as in the phylogenetic position of the taxa themselves An examination of the phylogeny below informs us that birds bats and pterodactyls each descended independently from a nonflying tetrapod ancestor that possessed a nonwing forelimb Similar structures that were not inherited from a common ancestor such as wings in this example are referred to as or In most all cases analogous structures seem to be adaptations to meet specific shared ecological challenges flight in the case of wings wings arise lt Origin of limbs Choanoflagellates ANIMALIA Porifera a 39 Cnidaria 39 Ctenophora Multiceilularlty Accelomorpha i LOPHOTROCHOZOA Bilateral symmetry Home Loss of coelom Platyhelminthes J Segmentation quotquot Annelida Bilateral symmetry Protostome Mouuska development PROTDSTOMES BILATERIA ECDVSOIOA 39 Nematoda H L Coelom cephalization CNS A thPOda Segmentation MUTEIOSTIIES Radial symmetry Echinodermata in adults Modern sequence based on DNA DEUTEROSTOMES Segmentation phylogeny of animal phyla The Fossil Record Sponges are the first animals Cnidarians ctenophores and in the fossil record other simple forms appear later quot 4 56 39quot 7 VT Bilaterians appear still later I Burgess Shale fossils 525 515 million years old 7 Doushantuo fossils lion years old Polar Triploid endosperm nuclei mother cell Endosperm 39 39 A 1 First ll Sperm Eclalleen division Basal cell Hypocotyl Shoot apical Procambium meristem Globular Cotyledon u Cotyledons proembryo Protoderm Cotyledons Endosperm Root apex radicle Root apical meristem The Seed Seed Coat 1 Procambium Cotyledons Root apical meristem Endosperm Root cap Megaspore mother cell Receptacle Stalk of ovule Pedicel funiculus Epicotyl Hypocotyl Withered cotyledons leaf Coleoptile Shoot removed here Intact plant Shoot removed Replacement shoot a Upper axillary bud released from apical dominance Shoot removed here x Shoot kmoved Intact Rooted Flowering plant shoot rooted shoot a Shoot florally determined Repression of floral inhibitors gt Activation of floral meristem identity genes Floral meristem merlstem 6 temperature Autonomous Temperature dependent pathway dependent Pathway pathway Whorl 2 Whorl 3 Petal Stamen Whorl 1 type 39 ral merist Stigma Anther Style Carpel Stamen L I Ovary Filament carpels stamens V V QVnoecium androecium I V Per 5 f i v Rece tacle petals corolla p Ovule Se al sepals calyx Separation layer Suberized cells of protective layer In This lecTur e we will discuss The morphology and anaTomy of planTs as well as some of Their funcTional aTTr ibuTes And because They compr ise The bulk of The exTanT land planTs This lecTur e will primarily focus on seed planTs ie gymnosper ms and angiosper ms Mer isTem cells play an impor TanT role in The lives of planTs Mer isTem cells are undiffer enTiaTed cells ThaT can give rise To var39ious specific Types of cells such ThaT dur ing developmenT a complex planT can be produced from a less complex planT embr yo In many r especTs The mer isTem cells of planTs are analogous To The sTem cells of animals When a mer isTem cell divides one of The 2 r esulTing cells remains a mer isTem cell while The oTher39 is free To differenTiaTe inTo anoTher39 Type of cell Because of This There is always a supply of mer isTem cells for fuTur e developmenT The elongaTion of planT r ooTs and shooTs r esulTs fr om miTosis of whaT are called apical mer isTems In addiTion laTer39al mer isTems faciliTaTe The increase in gir Th ThaT accompanies gr owTh in some vascular39 planTs such as Trees and shrubs Apical merisTems Apical merisTems are locaTed aT The Tips of planT shooTs and rooTs FyLre 2 Apical merisTems are responsible for primary growTh in planTs ie growTh ThaT is primarily associaTed wiTh The process of planT elongaTion Primary growTh produces primary Tissue which in Turn forms The primary planT body The primary planT body comprises The young sofT shooTs and rooTs of a Tree or shrub or The enTire planT body in some herbaceous planTs Apical merisTems are delicaTe groups of cells ThaT require proTecTion The rooT apical merisTem is proTecTed by The rooT cap which is derived from The apical merisTem iTself Fyure 3 The apical shooT merisTem is ofTen proTecTed by young leaves gure 4 An apical merisTem gives rise To Three Types of embryonic Tissue sysTems ThaT are TogeTher referred To as The primary merisTems eg Fyure 5 Cell division in and differenTiaTion of primary merisTem Tissue resulTs in The developmenT of The primary Tissues of The planT body The Three primary merisTem Tissues are Fyure 5 1 proToderm forms The epidermis 2 ground merisTem differenTiaTes inTo ground Tissuequot composed of parenchyma cells 3 procambium produces vascular Tissue 1 xylem and 1 phloem LaTeral merisTems While many sofT herbaceous planTs exhibiT only primary growTh elongaTion mainly To achieve Their adulT forms oThers such as Trees undergo significanT increases in girTh as well as elongaTion as They maTure These increases in girTh are referred To as secondary growTh To accommodaTe secondary growTh again resulTing in an increase in planT widThgirTh Trees and shrubs have an acTive laTeral merisTem A laTeral merisTem is a peripheral cylinder of merisTemaTic Tissue wiThin The sTems and rooTs Fyure 6 Woody planTs can have 2 laTeral merisTems Fyure 6 1 Cork cambium locaTed in The bark produces cork cells for The ouTer bark of a Tree Trunk or rooT This replaces The epidermis which is relaTively Thin and inelasTic in comparison To The bark Tissue 2 Vascular cambium locaTed JusT below The bark produces 2 vascular Tissue ie 2 xylem and 2 phloem ThaT is necessary for secondary growTh Tissue formed from laTeral merisTems is known as secondary Tissue and is collecTively referred To as The secondary planT body Secondary Tissue can accounT for mosT of The Trunk branches and older rooTs of Trees and shrubs Fyure 7 In a planT exhibiTing boTh primary and secondary growTh such as a Tree coordinaTion of primary and secondary merisTemaTic growTh produces The body of The adulT sporophyTe A vascular planT body has a rooT sysTem and a shooT sysTem gure 8 The rooT sysTem anchors The planT and faciliTaTes waTer and ion absorpTion from The soil for planT nuTriTion The shooT sysTem consisTs of sTems and leaves gure 8 STems serve as framework for posiTioning of The leaves Leaves are The primary siTes of phoTosynThesis The reiTeraTive repeaTing uniT of The vegeTaTive shooT consisTs of a series of inTernodes and nodes as follows Fyure 8 inTernode 9 node comprised of a leaf and an axillary bud 9 inTernode 9 eTc Axillary buds gure 8 are axillary apical merisTems derived from The primary Terminal shooT apical merisTem VegeTaTive axillary buds have The capaciTy To reiTeraTe The developmenT of The primary shooT Tip This could be imporTanT if The main shooT and iTs apical merisTem are desTroyed say for insTance by a planTeaTing insecT When a planT moves inTo iTs reproducTive phase axillary buds may go on To form flowers or floral shooTs PlanTs are comprised of Three basic Tissue Types each of which forms from a parTicular Type of primary Tissue as follows 1 dermis derived from The proToderm 2 ground Tissue derived from The ground merisTem 3 vascular Tissue derived from The procambium L Dermal Tissue The dermal Tissue dermis of planTs comprises The epidermal cells ThaT cover all parTs of The 1 planT body This epidermal layer is Typically 1cell Thick The exposed cell walls of epidermal cells are covered wiTh a faTTy exTra cellular layer comprising The cuTicle Fyure 9 In planTs such as deserT succulenTs ie cacTus a layer of wax may coaT The ouTside of The cuTicle To proTecT iT even furTher from desiccaTion A number of imporTanT specialized cells such as guard cells Trichomes and rooT hairs occur in The epidermis Guard cells Guard cells are paired sausageshaped cells ThaT Join TogeTher To form an opening called a sToma beTween Them gure 9 1 10 The diffusion of C02 inTo a planT Oz ouT of a planT and waTer vapor from a planT Takes place almosT exclusively Through The planT39s sTomaTa STomaTa and hence guard cells are mosT numerous on The leaves ofTen on The undersides of leaves Fyure 9 Guard cells can alTer Their shape and by doing so They can open or shuT The sToma pore beTween Them During periods of phoTosynThesis The sTomaTa are open Why Trichomes Trichomes Fyure 11 are hairlike ouTgrowThs of The epidermis Trichomes are ofTen found on sTems leaves and reproducTive organs where They give These sTrucTures a quotfuzzyquot appearance Trichomes can funcTion To keep The planT surface cool or warm They do This in large parT by helping conTrol The evaporaTion raTe and in doing so They can help The planT conserve waTer Some Trichomes are glandular and secreTe sTicky or Toxic subsTances To deTer herbivory RooT hairs RooT hairs Fyure 12 are Tubular exTensions of individual epidermal cells ThaT occur JusT behind The Tips of growing rooTs As microscopic exTensions of individual cells rooT hairs should noT be confused wiTh laTeral rooTs which are mulTicellular sTrucTures MosT of a planT39s waTer and mineral absorpTion occurs Through iTs rooT hairs because of Their large surface area Ground Tissue Ground Tissue derived from ground merisTem Tissue primarily consisTs of Thin walled parenchyma cells ThaT can funcTion in sTorage phoTosynThesis and secreTion Parenchyma Parenchyma cells are The mosT common Type of planT cell These cells have Thin walls large vacuoles and an average of 14 sides gure 13 Parenchyma cells are used To sTore food and waTer For example mosT cells of an apple are parenchyma cells Some parenchyma cells may live To be over 100 years old Some parenchyma cells conTain chloroplasTs and are called chlorenchyma cells Collenchyma Collenchyma cells gure 14 also can live for39 many years These are flexible cells wiTh Thickened cell walls ThaT pr ovide suppor T for planT gr owTh such ThaT The planT can bend wiThouT breaking Collenchyma cells ofTen for m sTr39ands or conTinuous cylinder39s beneaTh The epidermis of sTems of leaf peTioles sTalks and along The veins of leaves STr39ands of collenchyma provide much of The suppor T for sTems in which secondar y gr owTh has noT occurred The par T of celery ThaT we eaT has sTr ings ThaT consisT mainly of collenchyma and vascular39 bundles Sclerenchyma Scler enchyma cells Fyure 15 have Tough Thick walls and usually are dead once They maTu re The secondary cell walls of These cells are impr egnaTed wiTh a compound called lignin Lignin is a polymer ThaT makes The cell walls of scler enchyma cells more rigid Thus planTs use scler39enchyma cells To sTr engThen Tissues There are 2 Types of scler enchyma cells 1 Fiber s Fyure 15a long slender cells ThaT are grouped inTo sTr39ands The fabric linen is woven fr om fiber sTr ands of scler enchyma cells found in flax planTs 2 Sclereids Fyure 15b var iably shaped buT ofTen a branchedType of scler enchyma cell Scler eids can be grouped TogeTher or noT The gr iTTy TexTur e of a pear is cr eaTed by clusTer s of scler eids ThaT occur Thr oughouT The fr uiT They are someTimes called sTone cellsquot 3 Vascular Tissue Vascular Tissue includes 2 kinds of conducTing Tissues lem and phloem Xylem Xylem Fyure 16 is The principle waTerconducTing Tissue of planTs Xylem usually conTains a combinaTion of 2 Types of cell derivaTives wiTh Thick secondary cell walls conTaining lignin vessels and Tracheids gure 16 Tracheids dead cells ThaT Taper aT The ends and overlap one anoTher noTice The piTs beTween These cells in Figure 16a Vessels vessel members vessel elemenTs conTiguous Tubes formed from dead hollow cylindrical cells called vessel members arranged end To end noTice The pores beTween These cells in Figure 16a All vascular planTs possess Tracheids however only angiosperms and gneTophyTes have xylem ThaT conTains vessel elemenTs A Typical paTh for waTer flow wiThin a planT would be for The waTer To pass from The rooTs up Through The shooTs and inTo The leaves When iT reaches The leaves much of This waTer passes on as a waTer film To The ouTside of The parenchyma cells of The leaves IT Then diffuses in The form of waTer vapor ouT of The leaves via The sTomaTa and inTo The surrounding air The diffusion of waTer vapor from a planT is known as TranspiraTion In addiTion To conducTing waTer dissolved minerals and inorganic ions such as niTraTes and phosphaTes ThroughouT The planT xylem supplies mechanical supporT for The planT body Vessel members seem To conducT waTer more efficienle Than Tracheids In addiTion To conducTing cells xylem Typically includes fibers and parenchyma cells ie ground Tissue Primary xylem gure 17 is derived from The procambium which in Turn comes from The apical merisTem The primary xylem is associaTed wiTh porTions of The planT body ThaT are elongaTing Secondary lem FyUquote 18 is formed by The vascular cambium Le a laTeral merisTem ThaT develops laTer Than The apical merisTem The secondary xylem is associaTed wiTh an increase in The diameTer of The planT eg The secondary growTh ThaT resulTs in The Thickening of a Tree39s Trunk NoTe ThaT The secondary growTh Tissue secondary xylem and secondary phloem develops beTween The 1 xylem and 1 phloem gure 18 Wood Fyure 19 largely consisTs of accumulaTed secondary xylem And here iT39s inTeresTing To noTe ThaT The xylem cells formed early in The growing season are larger in diameTer Than Those formed laTer ThaT same year This alTernaTion of large and small xylem cells is whaT comprises The banding paTTern on crosssecTions of Trees Fyure 19 Each seT of bands large and small corresponds To a year39s growTh and Thus The bands can be used To age woody Trees gure 19 1 20 Phloem Phloem is comprised of modified cells locaTed near The ouTer parT periphery of rooTs and sTems Fyures 17 18 IT is The principle foodconducTing Tissue in vascular planTs Food conducTion in phloem is primarily carried ouT Through 2 kinds of cells 1 sieve cells 2 sieveTube members gure 21 BoTh of These 2 Types of cells possess clusTers of pores in Them known as sieve areas Sieve Tube member cells are nourished by companion cells a Type of parenchyma cell FyLre 21 Sieve cells are similarly Taken care of by albuminous cells Fibers and unspecialized parenchyma cells are ofTen abundanT in phloem WhaT abouT 1 and 2 phloem see gure 18 Please undersTand ThaT 1 phloem is derived from The procambium from The apical merisTem 2 phloem is derived from The vascular cambium laTeral merisTem Tissue RooTs Typically have a simpler paTTern of organizaTion Than sTems or leaves Four zones or regions are commonly recognized in developing rooTs Fyure 22 1 RooT cap 2 Zone of cell division 3 Zone of cell elongaTion 4 Zone of cell maTuraTion When apical iniTials ie The cells of The apical merisTem divide daughTer cells ThaT end up on The Tip end of The rooT become rooT cap cells Cells ThaT divide in The opposiTe direcTion developpass Through The 3 oTher zones before They finish differenTiaTing and maTuring RooT cap The rooT cap Fyure 22 funcTions To proTecT The delicaTe planT Tissue behind iT Cells in The rooT cap have a shorT life span abouT 1 wk Cells in The ouTer rooT cap laTeral rooT cap secreTe a slimy subsTance ThaT geTs released onTo The surface of The rooT cap To funcTion as a lubricanT of sorTs Collumella cells specialized cells in The cenTral rooT cap funcTion in The percepTion of graviTy Why is This imporTanT Zone of cell division IT39s wiThin The zone of cell division Fyure 22 ThaT The apical merisTem cells divide To produce The 3 primary Tissues ThaT we have discussed earlier ie The proToderm ground merisTem and procambium Zone of cell elongoTion In The zone of cell elongaTion gure 22 rooTs lengThen because cells produced by The primary merisTems become several Times longer Than wide Their widTh also increases sligthy Much of The increase in lengTh and widTh happens because vacuoles form in The cells unTil They occupy 90 or more of each cell No furTher increase in cell size occurs beyondabove The zone of cell elongaTion ie iT39s beyond This zone ThaT secondary growTh will produce The really significanT increases in planT girTh if iT is To occur Zone of cell moTuroTion AfTer The cell elongaTion ThaT Takes place in The zone of cell elongaTion planT cells become differenTiaTed inTo specific cell Types in The zone of cell maTuraTion Fyure 22 Cells of The rooT surface proToderm maTure inTo epidermal cells many of which will develop rooT hairs ThaT increase The surface area of The rooTs 12 Parenchyma cells are produced by The ground Tissue layer To form The corTex ThaT can funcTion as a locaTion for food sTorage for The planT eg see F39gure 23 The innermosT layer of The corTex differenTiaTes inTo a single layer of cells called The endodermis gure 23 The endodermis regulaTes waTer TransporT beTween The corTex and The vascular Tissue All Tissues inTerior To The endodermis are collecTively referred To as The sTele and are all derived from The procambium The ouTermosT cylinder layer of The sTele is The pericycle parenchyma cells ThaT can give rise To laTeral branch rooTs or in eudicoTs To parT of The vascular cambium Fyure 23 In monocoTs Fyure 23 and a few eudicoTs rooT 1 xylem is differenTiaTed as a ring of vascular bundles ThaT surround The cenTral core of parenchyma cells called The In mosT eudicoTs The 1 xylem is differenTiaTed in The cenTer of The rooT gure 24 Primary 1 phloem is differenTiaTed in groups of cells beTween The arms or bundles of xylem cells in boTh monocoTs and eudicoTs Fyures 23 24b In eudicoTs and oTher planTs wiTh 2 growTh parT of The pericycle and The parenchyma cells beTween The phloem and xylem arms become The rooT vascular cambium This layer produces 2 xylem To The inside and 2 phloem To The ouTside Fyure 18 As 2 growTh conTinues in The rooT and The secondary Tissues build up in concenTric cylinders layers The 1 phloem corTex and epidermis can become crushed and someTimes even sloughed off In The case of 2 growTh in eudicoT rooTs everyThing ouTside of The sTele is replaced by bark For a helpful overview of The differenTiaTion of planT Tissue see gure 25 Modified rooTs Because The primary funcTions of rooTs are anchorage and absorpTion mosT planTs produce eiTher a TaprooT sysTem or a fibrous rooT sysTem TaprooT sysTem a single large rooT wiTh smaller branch rooTs Fyure 260 Fibrous rooT sysTem many smaller rooTs of similar diameTer However many rooT modificaTions providing oTher funcTions are seen amongsT planTs Aerial rooTs are seen on orchids ThaT are epiphyTes ie They live on oTher planTs The rooTs of These planTs do noT exTend inTo The ground buT raTher sTick ouT inTo The air Prop rooTs as seen in corn Fyure 26b help To brace some planTs from wind acTion AdvenTiTious rooTs as seen in ivy planTs arise from along The sTem They help climbing planTs anchor Their sTems To Things such as Trees and walls PneumaTophores someTimes referred To as kneesquot are modified ouTgrowThs of rooTs ThaT are possessed by some planTs eg mangrove Trees gure 26cThaT grow in weT areas such as swamps These spongy ouTgrowThs grow To above The surface of The surrounding waTer To allow The planT To more easily geT 02 To iTs rooTs OTher Types of modified rooTs include conTracTile rooTs parasiTic rooTs food sTorage rooTs waTer sTorage rooTs buTTress rooTs The sTem is an axis from which various planT organs grow The shooT apical merisTem iniTiaTes The formaTion of sTem Tissue ExTernal sTem morphology The area of leaf aTTachmenT on a sTem is called a w Fyure 27 The area beTween Two nodes is called an inTernode Fyure 27 A leaf usually has a flaTTened M and a m sTalk gure 27 Leaves wiThouT peTioles are called sessile leaves An axillary bud Fyure 27 is produced beTween each peTiole and sTem JusT disTa To The peTiole Axillary buds are producTs of The primary shooT apical merisTem and They someTimes develop inTo branches or flowers MonocoT and herbaceous sTems are usually green and capable of phoTosynThesis InTernal sTem morphology The apical merisTems of sTems produce The primary merisTems ThaT increase sTem lengTh Three primary merisTems you guessed iT The proToderm ground merisTem procambium develop from The apical merisTem ProToderm gives rise To epidermis Ground merisTem produces parenchyma ces Procambium produces cylinders of primary xylem and primary phloem surrounded by ground Tissue A sTrand of xylem and phloem branches off from The main cylinder of xylem and phloem To enTer each developing leaf flower or shooT Fyure 6 In eudicoTs a vascular cambium develops beTween The primary xylem and primary phloem Fyures 2839 The vascular cambium gives rise To The secondary xylem and phloem MonocoTs Fyure 2 lack a vascular cambium and Thus They do noT exhibiT secondary growTh In woody eudicoTs and gymnosperms a second cambium The cork cambium gure 6 arises in The ouTer corTex To produce cork cells and ouTer bark Modified sTems AlThough mosT sTems grow erecT There are some sTem modificaTions gure 30 ThaT serve special purposes including ThaT of vegeTaTive propagaTion Bulbs bulbs Fyure 300 are possessed by such planTs as onions lilies and Tulips Bulbs are swollen underground sTems ThaT have advenTiTious rooTs aT The base MosT of The bulb consisTs of fleshy leaves Rhizomes rhizomes Fyure 30b are exhibiTed by such planTs as perennial grasses ferns and irises Rhizomes are horizonTal sTems ThaT grow underground AdvenTiTious rooTs grow from The sTem of a rhizome and leaves grow from The nodes and Tip Runners STrawberry planTs are an example of a planT wiTh runners Fyure 30c Runners are horizonTal sTems wiTh long inTernodes Tubers PoTaToes are an example of a planT wiTh Tubers Fyure 30d 16 Tubers are accumulaTions of carbohydraTes ThaT form aT The Tips of sTolons a Type of modified sTem The sTolons evenTually die leaving The Tubers eg poTaToes by Themselves in The soil Tubers have axillary buds on Them ie for example The quoteyesquot of a poTaTo Ten drils Climbing planTs such as grapes ofTen exhibiT Tendrils FyLre 308 Tendrils are modified sTems ThaT Twine abouT Things To supporT The planT Some Tendrils are acTually modified leaves Cladophylls Some cacTi possess cladophylls FyLre 30f Cladophylls are flaTTened phoTosynTheTic sTems ThaT resemble leaves In cacTi True leaves are presenT as spines These highly modified leaves are used for proTecTion Leaf exTernal sTrucTure Of course leaves are The primary siTe for phoTosynThesis on land The developmenT of leaves is iniTiaTed by The apical merisTem and leaves grow primarily via cell enlargemenT and some cell division Leaves firsT develop as leaf primordia Fyure 4ThaT are associaTed wiTh The axillary buds along The planT sTem However leaf primordia do noT have To become leaves They may develop inTo sTems There are 2 forms of leaves microphylls and megaphylls Microphylls These exhibiT one leaf vein They are found in species represenTing The phylum LycophyTa club mosses Megaphylls exhibiT several To many leaf veins megaphylls are possessed by mosT planTs Leaf veins are The vascular bundles wiThin The leaf Veins usually run parallel To one anoTher in monocoTs Fyure 31 and They are neTworklike in eudicoTs gure 31 The blades of leaves vary in form amongsT The various species of planTs Fyure 32 Simple leaves undivided leaves Fyure 320 Compound leaves The blade is divided inTo leafleTs FyLre 32b Leaves may be arranged alTernaTely 1 leafnode opposiTely 2 leavesnode or in a whorled fashion on a sTem gure 33 InTernal leaf sTrucTure gure 34 CuTicle a faTTywaxy covering ThaT Typically exisTs over The epidermis gure 34 The cuTicle has holes sTomaTa in iT ThaT faciliTaTe gas exchange and waTer regulaTion STomaTa discussed earlier are ofTen mosT numerous or only presenT on The undersides of leaves Epidermis a Thin TransparenT Typically no chloroplasTs presenT cell layer ThaT includes guard cells again usually guard cells are more numerous or only found on The undersides of leaves Fyure 34 Mesophyll comprises The bulk of The Tissue beTween upper and lower epidermis Fyure 34 The mesophyll is inTerspersed wiTh veins vascular bundles of xylem and phloem In eudicoTs The mesophyll has 2 regions The palisade mesophyll and The spongy mesophyll In The upper region ie The palisade mesophyll rows of Tigthy packed chlor enchyma cells exisT Below The palisade region and above The underlying epidermis and cuTicle is The spongy mesophyll layer39 IT conTains many air passageways ThaT connecT To The sTomaTa The mesophyll of monocoT leaves is noT differ enTiaTed inTo palisade and spongy layers and There is ofTen liTTle disTincTion beTween The upper and lower layers Modified leaves The following are JusT a few of The many Types of modified leaves Flor al leaves br acTs eg as possessed by poinseTTias Fyure 35d and dogwoods These are large modified leaves ThaT surround The True flower39s Because They are ofTen color ed flor al leaves are someTimes confused wiTh Tr ue flower39 peTals S ines eg as possessed by cacTi Spines can reduce waTer loss and also provide pr oTecTion Repr oducTive leaves These are leaves ThaT produce small planTleTs which when separ aTed from The leaf can spr ouT r ooTs and sTems and grow inTo new planT individuals For addiTional examples of some niny leaves see gure 35 quot21wam Trans v3 r i n Guard cell ta COO quot 39 quot ll ll agmm 3 7 L s a 9393 g a at quot 4 9 Epidermal cell Epidermal cell l Guard cell 39 7 Thickened inner wall of t guard cell Nucleus Chloroplast Primary path of water and mineral transport in vascular land plants 1 l3 9 3quotquot 7 a x g gt 7 lit quot Water exuts l u P39am throughL quot quot lntercellular space stomata gt 100 humidity Water moves up plant through xylem c quot 1 Water K 391 molecule Water enters r l i plant through roots l 943 Figure 363 Biological Science 29 D 2005 Pearson Prentice Halllnc Low water potential Atmosphere l39 952 MPa Changes with humidity usually very low Leaf 41 os MPa Depends on transpiration rate low when stomata are open Root II 06 MPa Mediumhigh Soil 4 03 MPa High if moist low if extremely dry High water potential II S Rootha inlarkiuli L5 Figure 37 8 Biological Science 2e 2005 Peatson Prentice Hall In E


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