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General Biology II

by: Einar Sanford

General Biology II BIOL 1120

Einar Sanford

GPA 3.84

Robert Reeder

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Robert Reeder
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This 27 page Class Notes was uploaded by Einar Sanford on Thursday October 15, 2015. The Class Notes belongs to BIOL 1120 at Motlow State Community College taught by Robert Reeder in Fall. Since its upload, it has received 15 views. For similar materials see /class/223574/biol-1120-motlow-state-community-college in Biology at Motlow State Community College.


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Date Created: 10/15/15
BlOL l 120 Reeder PHYLUM MOLLUSCA SOFT BODY I CHARACTERISTICS Contains snails slugs octopus squid and the quotshell fish clams oysterslimpets and scallops second largest WOO US as C171 E 1 3 VW Z Z 0 phylum greater than 100000 species Mollusks and Annelids supposedly share a common flatwormlike ancestor the larval stage also represents a possible relationship in evolutionary origin most zoologists agree that the mollusks were not derived from a metam eric ancestor but split off from the annelidarthropod line before the appearance of metam erism Are softbodied animals as the origin of their name suggests L mollis soft Most are marine with freshwater and terrestrial forms Majority are freeliving creeping slowly some attached others burrow a few float and some swim freely and quickly Bilateral symmetry most with no segmentation epithelium with cilia and many mucous glands All types of mollusks share 3 common features 1 Visceral mass contains internal organs such as the reproductive organs the heart digestive and excretory organs 2 Mantle fold of tissue covering the respiratory organs and visceral mass receives emptied products of the digestive excretory and reproductive systems may have sensory receptors for environmental sampling of the water contains glands that secrete the shell serves or gives rise to respiratory structures gills lungs provides jet propulsion in cephalopods 3 M muscular organ that may be adapted for either locomotion attachment food capture or a combination of functions Head region developed in gastropods snails amp slugs and cephalopods squid and octopus reduced in others m ventral and muscular body enclosed in a dorsal mantle soft thin membranous structure that lines the shell and surrounds the viscera within the mantle secretes the M if present Complete digestive tract mouth comm only with rasping protrusible tonguelike organ radula of minute horny teeth not found in pelecypods for scraping food a large digestive gland quotliverquot and generally salivary glands Dorsal heart usually in a pericardial w allows for free movement of pumping action auricles 2 or 1 l ventricle an anterior Lrta and often other blood vessels open system hemocoel heart usually 3chambered respiratory pigmentation found in the blood closed in cephalopods l The heart pumps blood into a single blood vessel aorta that may branch 2 Blood flows into a network of large spaces sinuses that bathes tissues directly hemocoel 3 Blood drains into vessels that carry it to the gills 4 From the gills blood flows back to the heart Respiration by g l to many by a lung in the mantle cavity by the mantle or by the epidermis Reduced coelom Hemocoel type Heart into a single vessel aorta into smaller vessels into sinuses that bathe tissues to gills amp back to heart remnants of the coelom remain near the heart Excretion by Kidneys nephridia single or 1 to 5 pairs opens into the pericardial cavity which empties into the mantle cavity Nervous system typically with 3 pairs of ganglia in head foot and viscera and both lengthwise and crossconnectives sense organs variously for touch taste and smell for sight eyespots EVE and for equilibrium statocysts Usually dioecious gonads 2 or 1 with ducts commonly external fertilization mostly oviparous producing eggs that hatch outside the mother39s body development either direct or with larval stages trochophore larva free swimming ciliatedtopshaped also characteristic of annelids implying some degree of common origin II CLASSES A Gastropoda snails slugs limpets conchs and others with unchambered shells of one piece called a univalve 39 quotbellyfootquot largest and most successful class of mollusks l 19 Characteristics a Usually in a coiled shell or uncoiled or absent b Well developed head with radula c Foot large and flat Example terrestrial snail a Fleshy head with two pairs of retractile tentaclesone pair of em on posterior tentacles and the mouth aquatic snails have only one pair of tentacles b Joined directly to the head is the long muscular ventral m on top of which are the soft internal organs coiled inside the spiral limy M some types without a s e c Genital pore opens on the right side of the head39 the small M and larger respiratory pore are in the soft mantle margin at the edge of the shell39 respiration by lungs terrestrial or gills aquatic d Each snail has a combined male and female reproductive system39 cannot selffertilize hermaphroditic e Herbivorous vegetation f A slime gland located in the forward part of the foot secretes a thin film of mucus over which the snail then moves by means of wavelike contractions of the foot muscles The shell offers protection as well as prevents drying out for adaptation to land g B Pelecypoda mussels clams oysters with shell of two pieces called a bivalve 39 quothatchet footquot 1 Characteristics 19 a b C Body enclosed in a twolobed mantle Shell of two lateral valves with dorsal hinge39 80 have shells less than 5cm giant clam of lndo Pacific coral reefs reach 15 m length and weigh over 225 kg Greatly reduced head39 w radula filter feeder Example Freshwater clam a b e f Soft body compressed between two shells lack a head39 wedgeshaped foot39 marine and freshwater forms some creep some burrow while others attac Somewhat oval shells marked by concentric growth lines centered around a swelling the umbo near anterior dorsal edge39 a dorsal mge ligament holds shells together dorsally and tends to make them separate ventrally interior surface of each valve has scars indicating points where the several muscles attach and act to close the valves and to extend or contract the foot anterior and posterior adductors Body consists of visceral mass contains digestive and reproductive organs anteroventral part forms the m on each side is a pair of thin platelike g body surrounded by the mantle Posteriorly mantle margins form 2 openings a larger smooth edged ventral incurrent siphon water com es in to gills for gas exchange an a dorsal excurrent siphon rough serrated edges Digestive system mouth anteriorly between two thin flaps palps short esophagus round stomach which receives ducts from a paired digestive gland liver a slender coiled intestine a dorsal rectum surrounde by the heart and a M opening into the excurrent sip on Circulatory system dorsal heart with auricles and a muscular ventricle enclosed in a pericardial amp ventricle pumps blood carrying nutrients and oxygen through the anterior and posterior aortas to all parts of the animals39 some blood returns in veins and some enters tissue spaces that diffuses back to heart OPEN system in aquatic forms the 3 chambered heart pumps blood through the gills and mantle for oxygenation and into the kidneys for waste elimination Ushaped kidney drains waste from pericardial sac and discharges into the interior chamber of the mantle Nervous system 3 pairs of ganglia connecting with nerves to various organs sense organs include light receptors in the mantle margin statocysts in the foot and chem oreceptors for testing water in the incurrent siphon Dioecious 2 branched gonads ovaries or testes in the visceral mass external fertilization egg and sperm discharged into the water microscopic larvae result later to acquire a shell and become a miniature of the species C Cephalopoda squid octopus nautilus etc quothead footquot 1 The most highly developed of the mollusks possibly the most complex brain of all invertebrates with vision as their highest developed sense 19 C Characteristics a Shell reduced internal absent or distinct b Welldeveloped head with eyes Radula present BIOL 1120 REEDER SEX HORMONES AND OTHER REPRODUCTIVE PROCESSES Male Sex Hormones as a group the male sex hormones are termed androgens and they include substances produced by the adrenal cortices and the testes Among the androgens testosterone is by far the most important It is produced and secreted by interstitial cells of the testes under the in uence of g also called ICSH in the male Although stimulates primary sperrnatocytes to undergo meiosis in process of spermatogenesis sperm cells do not mature completely unless testosterone is present T is also 1 quot 39 for secondary sexual 39 39 39 which include 1 Enlargement of penis scrotum prostate gland seminal vesicles Cowper s gland and the testes Increased growth of body hair particularly on face chest axilla underarms and pubic region Enlargement of larynx and thickening of vocal cords accompanied by development of a lowerpitched voice Thickening of the skin Increased muscular growth accompanied by development of broader shoulders Thickening and strengthening of bones WM VV C UIJB VVV To summarize under in uence of FSH the testes of a male child rst begin to produce sperm cells and under in uence of LH the interstitial cells produce and secrete testosterone GRH release hormone from hypothalamus in uences the release of FSH and LH from anterior pituitary Pube secondary characteristics begin to appear between ages 10 and 11 with gamete production beginning between ages 15 and 17 average The concentration of testosterone in the male body is regulated so that it remains relatively constant from day to day Negativefeedback System As concentration of testosterone in blood increases hypothalamus becomes inhibited thereby stimulation of anterior pituitary is decreased As pituitary s secretion of LH is decreased the amount of testosterone is reduced also and viceversa Female Sex Hormones The hypothalamus releases GRH which in turn stimulates anterior pituitary to release FSH and LH gonadotropins Although several different female sex hormones are secreted by various tissues including the ovaries adrenal cortices placenta and embryonic tissues during pregnancy these hormones belong to two major groups that are referred to as the estrogens and progesterones The primary source of estrogen in nonpregnant female is the ovaries and it corresponds in its effects to testosterone in the male Development and maintenance of secondary sexual characteristics by estrogen include 1 Enlargement of vagina uterus uterine tubes ovaries and external reproductive organs 2 Growth of the breasts and development of ductile system of mammary glands 3 Increased deposition of adipose tissue in subcutaneous layer particularly in breasts thighs and buttocks 4 Increased vascularization blood vessel growth of the skin Other changes that occur in female at puberty seem to be related to androgen concentration secreted by the adrenal cortices and ovaries These are increased growth of hair in pubic and axillary regions On the other hand the development of the female skeletal con guration which includes narrow shoulders and broad hips seems to be related to a lack of androgen Pube secondary sexual characteristics begin to appear between ages 8 and 9 due to androgen release pubic and axillary hair breast size increases noticeably at age 12 menarche occurs with the rst ovulation at 69 months later The ovaries are the primary source of the gestatog hormone progesterone in a nonpregnant female The effects of this hormone are related mainly to changes that occur in the uterus during the rhythmic reproduction cycles preparation of the endometrium for implantation of a fertilized ovum and the mammary glands for milk secretion biol l207humanisex7hormones 22504 Menopause The period of life in the late forties when menstrual cycle terminates The cause of menopause seems to be aging of the ovaries After about 35 years of cycling few primary follicles remain to be stimulated by pituitary gonadotropins Consequently follicles no longer mature ovulation does not occur and the blood level of estrogen decreases greatly As a result of low estrogen the female secondary sexual characteristics undergo changes The vagina uterus and uterine tubes decrease in size as do the external reproduction organs Pubic and axillary hair becomes thinner and breasts regress Also since estrogen is decreased FSH and LH are no longer inhibited and they are released continuously resulting in unpleasant symptoms occasionally sensation of heat in the face and upper body called a quothot ash quot Vaginal tissues become dry and reduced in size causing some discomfort for some women during sexual intercourse The Birth Process Parturition Pregnancy usually continues for a period of 40 weeks 266 days from conception or about 9 calendar months The pregnancy then terminates with the birth process parturition with the events preceding it called labor Progesterone suppresses uterine contractions during pregnancy Estrogen on the other hand tends to excite such contractions and as the time for birth approaches there is a change in the proportions of progesterone and estrogen that are secreted by the placenta More speci cally after the 7th month the placental secretion of estrogen increases to a greater degree than the secretion of progesterone Result is that the contractility of the uterine wall is enhanced The stretching of the uterine and vaginal tissues late in pregnancy is thought to initiate impulses to the hypothalamus which in turn signals posterior pituitary to release oxytocin powerful stimulator of uterine contractions its effect combined with decline in progesterone is thought to initiate labor Once labor starts rhythmic contractions begin at the top of uterus and travel down its length forcing contents of uterus toward the cervix Since the fetus is usually positioned with its head downward labor contractions force the head against the cervix This action causes stretching of the cervix which is thought to elicit a re ex that stimulates still stronger labor contractions At the same time dilation of the cervix re exively stimulates an increased release of oxytocin from pituitary The woman often feels a gush of uid which is the amniotic uid spilling out of its sac as it is punctured by the downward movement of the fetus Labor s onset may not be this abrupt as the woman may detect a slight discharge from the vagina consisting of blood and mucus This quotbloody showquot signals the onset of labor within a day or two or sooner Or a woman may begin to feel very mild contractions or labor pains in her abdomen every 20 minutes or so whether or not the amniotic sac is broken or bloody show appears Labor is quite different for each woman and for each pregnancy The contractions may last for days or as little as an hour or two typically lasts about 12 hrs Usually labor for a rst baby lasts about 24 hours and about 12 to 18 hours for a woman who has already had a baby Initially the cervix is a thick closed band of tissue With each contraction it dilates opens and will be stretched open to about 10 cm by end of labor s rst stage As labor continues abdominal wall muscles are stimulated to contract which will aid in forcing the fetus through the cervix and vagina to the outside Prompted by hormones uterine contractions gradually increase in frequency biol lZOihumanisexihormones 22504 BIOL 1120 REEDER SEX DEVELOPMENT The sex of an individual depends on two processes 1 Sex determination genetic make up of an individual 2 Sex differentiation embryonic development of the reproductive system in utero 1 Genetic Sex A Determined by examining for the presence of either an XX or XY sex chromosomal complement a genetic female and genetic male respectively 1 Determination of genetic sex can be made from time of conception and throughout rest of a person s life span by looking for presence or absence of sex chromatin called a Barr Body and results from a process which occurs only in early female embryonic development amp inactivation a This chromatin material is found in somatic cells throughout the body of genetic females XX b Cell samples from buccal mucosa scrapings stained with dye that attaches to chromatin within nucleus examined under the microscope sex chromatin material seen just inside inner surface of nuclear membrane c The presence of sex 39 quot 39 quot 39 the true sex as female Determination for presence of Y chromosome made by staining nuclear chromatin with dye that uoresces under ultraviolet light examine under a microscope using ultraviolet illumination show a single uorescent spot within nucleus a This establishes the person as a genetic male E B Genetic sex is E at the time of conception and depends on which type of sex chromosome is contained within the fertilizing sperm X or Y Since half sperm contain an X and half a Y chances should be statistically equal that one or the other will fertilize the ovum however in practice this may not be true because factors other than chance play a role Examples a Ychromosomes are smaller than X and contain less genetic material therefore Y are less dense and may be more motile b May be differences in length of time sperm are viable so that time of ovulation could bias fertilization in favor of one sex over another 1 Alkaline pH at ovulation time favors Y 2 Acidic before ovulation favors X 3 Y chromosome carries holandric genes testisdetermining factor N N 11 Hormonal Control of Differentiation A First weeks of life embryo 1 Sex structures of both male and female remain identical and undifferentiated B Development 1 By 5th week of embryonic life the primordial from the beginning by the original gonad develops 2 Germ cells migrate from yolk sac and incorporate into developing testes if male 3 By 7th week sufficient differentiation has occurred so that the testes can be histologically identified in embryos with XY Interstitial cells or Leydig cells begin secreting androgenic hormone testosterone Testosterone induces further differentiation of primordial sex structures into those of male 9399 B101120SEXDEVELOPHUMAN 123001 BIOL 1120 REEDER Plant Structure Growth and Differentiation 1 Plant Features A General Characteristics and Terminology Approximately 313000 species of plants 90 are angiosperrns 2 Most are either herbaceous or woody l a b Herbaceous do not develop persistent woody parts above ground Woody plants tree amp shrubs develop persistent woody parts 3 Annuals herbaceous types corn marigold geranium that grow reproduce and die in one year 4 Biennials herbaceous types cabbage carrot beet that take two years to complete their life cycle before dying a They produce and store eXtra food in their rst season which they then use during their second year for ower formation and reproduction 5 Perennials live for a number of years and may be herbaceous or woody a C Herbaceous perennials in temperate climates rhubarb onion iris asparagus have aerial stems that die back each winter their underground parts underground stems and roots enter winter dormancy and send out new growth in the spring In tropical climates pronounced wet and dry seasons herbaceous perennial s aerial parts die back with their underground parts entering dormancy during the dry season other tropical types orchids grow yearround All woody plants are perennials with some species living hundreds to thousands of years 1 in temperate areas aboveground stems become dormant in winter most shed their leaves before winter and produce new stems with new leaves in the spring B The Plant Body Comprised of a shoot system stems leaves owers and fruits containing seeds and a root system Plant tissues composed of either one kind of cell simple or two or more kinds compleX Plants have three tissue systems 1 2 3 4 biol 120 jlantistructureigrowthdoc a b C Ground tissue system comprises most of the plant body functions include photosynthesis storage and support Vascular tissue system functions include substance conduction water dissolved minerals and dissolved sugar as well as strengthening and support tissue Dermal tissue system plant body covering serving for protection Plant organs are composed of several different tissues roots stems leaves ower parts fruits Tissue systems of different plant organs form an interconnected network throughout the plant Ground tissue system is composed of three tissues r 39 quot 39 and 39 a 57 C d Are distinguished by their cell wall structures Growing plant cells secrete a thin primary cell wall cellulose which stretches and eXpands as the cell increases its size When growth ceases the cell may secrete a thick strong secondary cell wall inside the primary one and its membrane a Lignin a strengthening polymer of amino acids comprises about 35 of secondary cell walls Parenchyma the principal living and metabolizing cell found throughout the plant body functions include photosynthesis secretion and storage starch grains oil droplets water and salts cellulose is predominant in its thin primary cell walls Collenchyma gives eXibility and provides much of the support in the soft nonwoody plant organs living cells are usually elongated with unevenly thickened primary cell walls due to pectin and thick comers not found uniformly throughout plant but typically occurs as long strands near stem surfaces and leaf veins Sclerenchyma also specialized for support due to eXtreme thickening of its secondary cell walls lignin endowing strength and hardness at its functional maturity the cells often die 1 Located in several plant body areas V N V 32709 2 Two types of cells sclereids and bers a Sclereids short cubical cells common in nut shells and the pits of stone fruits cherries peaches b Fibers long tapered cells occurring in patches or clumps particularly abundant in wood and bark of angiosperms hardwood vs softwood differences 7 Vascular tissue system embedded in the ground tissue functioning to transport materials throughout the plant via xylem and phloem a Xylem conducts water and dissolved minerals sap up from the roots to the stems and leaves as well as gives structural support Angiosperms contain four different cell types tracheids vessel elements parenchyma and bers of which tracheids and vessel elements are for conduction parenchyma for storage and bers for support Gymnosperms and seedless vascular plants utilize mainly tracheids only for conducting in their xylem Tracheids a At maturity are dead and hollow with only cell walls remaining b Are long and tapering located in patches or clumps c m thin areas in tracheid end walls primary wall but no secondary serve as the water passageways from tracheid to tracheid Vessel elements more ef cient water conduction cells of angiosperms a At maturity are dead and hollow with only cell walls remaining b Wider cell diameter than tracheids c End walls either have holes perforations or they are entirely dissolved away d Are stacked one on top of the other resembling a water pipe e Have pits for lateral transport in their side walls as well b Phloem conducts dissolved sugar throughout the plant as well as gives structural support more compleX Angiosperms contain four different cell types sieve tube members companion cell bers and parenchyma of which sieve tube members conduct companion cells aid sieve tube member functioning bers support and parenchyma store 2 Seedless vascular plants and gynmosperms have only sieve cells for conductive purposes 3 Both types of cells have clusters of pores known as sieve areas a Sieve areas are more abundant on the overlapping ends of the cells and connect the protoplasts of adjoining sieve cells and sieve tube members 4 Sieve tube members a Are living at maturity with cytoplasm but no nuclei mitochondria vacuoles and ribosomes 1 Typically live less than a year b Are stacked endtoend form long sieve tubes End walls called sieve plates have larger pores through which cytoplasm of one sieve tube member eXtends into the neXt Adjacent companion cells which are living help direct sieve tube member s activities moves sugar into the sieve phloem transport Plasmodesmata cytoplasmic connections through which cytoplasm eXtends between adjacent companion cells and their sieve tube member as well as between phloem conducting cells 8 Dermal tissue system consists of the epidermis and periderm and provides a protective covering over plant parts a Herbaceous plants have only a singlelayered epidermis b Woody plants initially produce an epidermis that splits apart during growth in diameter 1 Periderrn many layers in thickness comprises the outer bark and replaces the epidermis in the stems and roots of longerlived woody plants c Epidermis typically a single layer V N V 9 V 4 V V V 83 I V biol 120 jlantistructureigrowthdoc 32709 V Epidermal parenchyma are transparent generally contain no chloroplasts and allow light to penetrate into the interior tissues location of photosynthetic tissues In aerial parts stems and leaves the epidermal cells secrete a cuticle waxy layer over the surface of their walls controls water loss and diffusion of gases COZOZ water vapor Tiny pores stomata formed and regulated by a pair of round cells guard cells serve signi cantly in water gas and even temperature control a Stomata are generally open during the day photosynthetic activity and time of water loss and cooling and close at night to conserve water when photosynthesis is not occurring and cooling is not required Outgrowths or hairs trichomes may occur in many sizes shapes and functions 1 Root hairs increase the absorptive surface area 2 In salty environments leaf trichomes remove excess salt 3 Desert plants aerial parts have trichomes which increase light re ection cooling and decreases water loss 4 Protective function on stinging nettle leaves and stems via the presence of irritating substances that discourage herbivorous animals from eating the plant d Periderm forms the outer bark of older stems and roots 1 Periderm replaces epidermis as it is sloughed off as woody plants begin to increase in girth secondary growth It is composed mainly of cork cells and cork parenchyma also contains cork cambium a Cork cells die at maturity with walls that have water proo ng substances in a heavy coat b Cork parenchyma function in storage c Cork cambium lateral meristematic tissue N V W V 4 V 2 V II Plant Growth A The Complex Growth Process 1 Involves three different processes cell division cell elongation and cell differentiation a Cell division or mitosis results in an increase in cell numbers b Cell elongation is cell expansion and occurs as the vacuole lls with water exerting cell wall pressure causing expansion c Cell differentiation maturation is specialization into the various mature plant body types parenchyma collenchyma vessel elements tracheids etc capable of various functions is essential for tissue formation The location and time length of growth differs between plant and animals a All parts of an animal grow typically in its early years at different rates b When plants grow cells divide only in speci c areas called meristems 1 These cells do not differentiate and retain mitotic capability unlike differentiated cells 2 Result is that plants can grow throughout their life 3 Found in the outer and inner bark stem and root tips buds 3 Two types of plant growth a Prima growth length increases of a plant 1 Forms the entire plant body in herbaceous types and the young soft shoots and roots in woody trees and shrubs 2 All plants have primary growth forms all of rst years tissues and parts b Seconda growth girth increases of a plant extended life l Primarily the gymnosperms and woody dicots are the only plant types with secondary growth exceptions are certain annuals geranium and sun ower and monocots palms that have secondary growt 2 Tissues produced by secondary growth comprise the wood and bark the bulk of trees and shrubs 4 Primary growth results from apical meristem activity a Root tips and stem buds have apical meristems 1 First part of the bean embryo to begin growth is the radicle embryonic root Equot biol 120 jlantistructureigrowthdoc 32709 BIOL l 120 REEDER CHARACTERISTICS OF THE ANIMAL IGNGDOM I Characteristics true multicellular eukaryotic lacking cell wall plastids and photosynthetic pigments heterotrophic and motile at some stage in their life cyc e A Presence or Absence of Backbone l Invertebrates lacking a supportive and protective backbone majority of animals 97 of all animals 2 Vertebrates segmented internal endoskeleton composed of cartilage or bone39 only one subphylum Vertebrata of the phylum chordata contains all the vertebrates B Body Symmetry l Asymmetrical body not divisible equally into parts some Porifera 2 Symmetrical divisible into equal parts a Radial symmetry multiple planes through the central body longitudinal axis will divide the animal into radial sectors as in pie pieces or can be divided into similar halves by more than two planes passing through the longitudinal axis tubular vase or bowl shapes in which one end of the longitudinal axis is the mouth 1 body parts arranged around a central axis so that stimuli is received from all directions equally 2 organism has a top and a bottom 3 suitable for sedentary or sessile life style some Porifera Cnidaria Echinoderms b Bilateral symmetry sagittal plane down length of animal through its midline divides the animal into equal and opposite halves or mirror images suitable for active movement 2 many show cephalization definite heads with concentrations of sensory structures on anterior end of their body which is better fitted for directional movement 3 most of the other phyla such as Chordates Annelids 4 Related anatomical terminology for lower animals most animals with longitudinal axis parallel to the earth s surface majority are guadrupeds a Anterior part that moves forward usually contains mouth b Posterior opposite side or end to anterior39 end equipped with tail for swimming or that follows c Dorsal back or upper surface d Ventral belly or under surface 5 For humans bipeds anterior is synonymous with ventral and posterior implies the same as dorsal superior and inferior ends 3 longitudinal plane down the organism39s length 4 transverse plane cross section perpendicular to the longitudinal axis of an organism C Body Spaces or Cavities l Acoelomata lacking a body space outside the gut39 Nemertea and Platyhelminthes 2 EuCoelomata having a quottruequot body cavity or coelom space between the gut and the body wall formed within the mesoderm and lined by a mesoderm al derived membrane mesenteria andor peritoneum usually with excretory and reproductive ducts leading to the exterior39 characteristic of the higher phyla Mollusca through Chordata with variations limitations in space size amp lining a Variations l Pseudocoel unlined coelom that develops between the mesoderm and endoderm and is filled with uid Nematoda and Rotifera 2 Hemocoel greatly reduced coelom with blood circulating in some or no vessels and instead in spaces between the internal organs Mollusca Arthropoda39 called a quotblood cavity b The pseudocoelom hemocoel and larger spacious true coelom may all function as a quothydrostatic skeleton 3 Significance ofa coelom a limitations of a solid body as in flatworms a solid worm has no internal circulatory and may not have a digestive system39 all of its internal organs are pressed on by muscles and are deformed by muscular activity b By possessing a coelom the body39s organs may be located within a lined enclosure where they can function without having to resist muscular pressures especially circulatory digestive and reproductive organs greater body flexibility and permits a greater size and complexity l Digestive tract may move food independently of body movement 2 coelom may act as a hydrostatic skeleton assists support circulation respiration and excretion 3 pumping of heart for greater circulatory efficiency 4 enlargement of female abdominal area during pregnancy and breeding39 allow for gametes to accumulate 4 True coelomates include Mollusca Annelida Arthropods Echinoderms and Chordates biol lZchharacteristics animal kingdomdoc 11808 D Digestive Tract Type or Gut and related Body plan 1 m digestive tract with m body plan Porifera utilize specialized cells via pores amp a filter feeding process 2 Incomplete mouth only quotsac body plan Coelenterates Cnidaria Platyhelminthes 3 Complete mouth and anus quottube within a tubequot all other phyla allows for greater digestive specialization E Embryonic Developmental Stages sometime after emergence of bilateral body plans two key evolutionary groups opened up 1 zygote fertilized egg undergoes a series of mitotic divisions cleavage eventually forming an embryonic stage called the blastula many celled stage with fluidfilled cavity 2 In most higher animals the blastula folds inward at one point ultimately resulting in an opening at one end of a forming tube called the blastopore 3 Developmental stage called the gastrula will next form whose development is significant to the evolutionary phyla relationships of higher animals and their advancement 4 Classification will be based on the result of blastopore differentiation the cleavage first several divisions of the embryo pattern and the cleavage type a Protostomes l Blastopore becomes the mouth of the digestive tube 2 Spiral cleavage pattern spiral arrangement of cells resulting from the initial cell divisions that occur obliquely to the polar axis any one cell is located between two cells above or below it 3 Fate of each embryonic cell is fixed early determinate cleavage 4 In most of the mollusks annelids and arthropods possibly some flatworms b Deuterostomes Blastopore becomes the anus of the digestive tube 2 Radial cleavage pattern cells located directly above or below one another resulting from early divisions which are either parallel or at right angles to the polar axis cells are located directly above or below one another stacked in layers 3 Each early embryonic cell has the potential to develop into an entire organism indeterminate cleavage 4 In echinoderms and chordates F Embryonic Development Concerning Number of Germ Layers gastrulation relates to the potential for tissue development and in turn more complex development organs organ systems a tissue consists of a few types of closely associated cells adapted to carry out specific functions 1 Classification a No tissue development Porifera b Diploblastic 2 layers ectoderm and endoderm Coelenterates or cnidarians represent the lowest phylum with tissue forming capability c Triploblastic 3 layers ectoderm endoderm mesoderm Platyhelminthes and all higher phyla 2 Germ layers allow for greater cell specialization division of labor a Ectoderm skin sense organs nerve system and specific glandular epithelium pineal pituitary and adrenal medulla b Mesoderm muscles circulatory system reproductive system excretory system skeletal system glandular epithelium c Endoderm epithelium of the digestive tract and the respiratory tract glandular epithelium thyroid parathyroid pancreas and thymus G Bodily Support to a True Skeletal System 1 Hydrostatic skeleton any fluidfilled body cellular space andor cavity pseudocoelom or coelom which helps support the body wall and offer resistance and support by which muscular contraction can occur it transmits force when contractile cells contract against it coelenterates and annelids assists circulation respiration and excretion as well a Because fluids cannot be compressed force is transmitted through the fluid causing change in shape and movement of the bod b Works something like a balloon filled with water c Primary examples cnidarians and anneli s d Also supplemental in complex invertebrates with shells or an endoskeleton clam s foot sea star s and sea urchin s tube feet the penis copulatory organ r V 2 Exoskeleton external framework typically composed of calcium carbonate CaCo3 lime such as in the corals clams and snails or chitin in the arthropods crab insects lobster 3 Endoskeleton internal framework of siliceous spicules and the protein spongin as in sponges g of cartilage andor bone in the chordates sharks birds reptiles fishes hum ans g Cva in starfish 4 The exoskeletons of mollusks and arthropods are nonliving while the endoskeleton of vertebrates represents living tissue biol lZOpcharacteristics animal kingdomdoc 11808 H Segmentation or Metam erism l Implies a linear repetition of body parts internally andor externally with each repeated unit termed generally a somite underlies the organization of all advanced animals built in redundancy as a safety factor Examples a In earthworms externally has successive somites as well as internally the repetitive arrangement of organs and systems digestive tract and the partitioning off of segments b In crayfish and insects externally three distinct body regions head thorax abdomen in some the segments may be fuse c In chordates and man internally vertebral column body muscles and nerve pathways I Possessing External Appendages for Locomotion Feeding etc 1 Examples a Tentacles of sea anemone jellyfish Hydra minute setae of earthworms legs pincers swimmerets of arthropods fins legs and wings of vertebrates I Reproduction 1 Sexual reproduction is the general rule for animals meiosis occurs in the gonads producing nonmotile eggs and agellated sperm may be external or internal fertilization zygote passes through a series of embryonic stages resulting in an immature form or larvae a animals are mainly diploid organisms with gametes the only haploid cells in their life cycles 2 Types a Monoecious or hermaphroditic individual animal contains both male and fem ale sex organs some Poriferans Coelenterates atworms earthworms and leeches b Dioecious separate and distinct sexes most of the higher phyla 3 some asexual examples typically for regeneration of a lost body part sponges lizard39s tail starfish arm but may be for production of new individual sponge farming budding in the hydra K Circulatory System mechanisms to supply or transport materials gases nutrients wastes advancement requires 1 blood 2 heart for pumping 3 system of vessels or spaces to circulate the hydrostatic skeleton assists transport in lower forms 1 m specialized circulatory structures present in sponges cnidarians atworms or nematodes hydrostatic skeleton assists a Tissues are bathed in uid laden with oxygen amp nutrients in aquatic forms b Wastes simply diffuse into the uid and are washed away Types a Qpen the heart pumps blood via vessels into the body cavity portions or sinuses so as to bathe the internal organs and then may return the blood to the heart via ostia equipped with valves as in insects or blood passes into open ended vessels that lead to the gills and then to vessels back to the heart as in mollusks l Hemocoel blood filled sinuses types Insects mollusks snail clam crayfish crab 2 Sluggish inefficient movement colorless blood no respiratory pigment in many 3 In the clam blood is pumped both forward and backward by the heart b Closed blood is always contained within blood vessels interstitial uid is separate from the blood typically hemoglobin as the respiratory pigment 1 Quick responses because blood can be supplied on demand to the needing tissue skeletal muscle 2 Presence of a respiratory pigment aids gas transfer L Respiration Organism ic and Cellular 1 Four specializations for the exchange of gases a Integumentag Exchange body surface for exchange diffusion of gases hydrostatic skeleton and usually with no circulatory system Porifera Coelenterata Platyhelminthes Nematoda Anne i l Supplements breathing by means of gills and lungs in certain vertebrates amphibians fishes 2 lower metabolic rate requires smaller quantities of oxygen b moist outgrowths of the body surface that are exposed to water starfish clam crayfish amphibians fishes each gill consists of many filaments containing blood vessels c Tracheal System network of air tubes found in insects and other terrestrial arthropods which open externally via tiny holes spiracles on the body surface leading to all parts of the body terminating in uidfilled tracheoles d Lungs most terrestrial animals have surface ingrowths or from the wall of a body cavity protected from desiccation highly vascularized so that the circulatory system assists the transfer of gases typically utilizing a respiratory pigment plus muscle system assistance ventilation vertebrates contain a series of air passageways terminating in thinwalled air sacs alveoli N 19 biol lZOicharacteristics animal kingdomdoc 11808 BIOL 1120 Reeder THE TRACHEOPHYTES I THE SEEDLESS VASCULAR PLANTS Ferns and Fern allies evolved approximately 420 million years ago Phylum Pterophyta l Ferns a Characteristics that distinguish the ferns from the other lower seedless vascular plants 1 Leaf structure large compound branching leaves fronds that develop by uncoiling fiddleheadsquot for some ferns 2 Stem anatomy contains m a quotpackingquot tissue that also occurs in seed plants 3 Location of sporangia borne on the fronds in clusters called m pl 4 Pattern of development the sporophyte becomes the conspicuous independent plant body developing from the gametophyte and is considered dominant due to its large size and persistance for extended time period the gam etophyte dies soon after reproducing 5 Onlv the sporophyte has vascular tissue while the gam etophyte lacks it 6 Sporic life cycle primarily homosporous with some heterosporous examples b Widely distributed in both the tropics and temperate regions damp and shady places c Temperatezone ferns have horizontal asexual underground stems called rhizomes usually perennial growing on or just beneath the surface of the soil from which grow hairlike roots and fronds d The leafy frond sporophyte becomes independent of the flat green photosynthetic heartshaped prothallus gametophyte which grows flat against the ground 1 2 3 6 B Phylum Psilo l Whisk ferns simplest vascular plants only two species remainin Sporophyte lacks true root and leaves but have vascularized stems serves as the photosynthetic organ a b c e C Phylum Sphe l 1 The prothallus lacks vascular tissue and has tiny rootlike rhizoids for anchoring The prothallus produces archegonia and antheridia on its underside The gametophyte generation can survive only where there is plenty of moisture and shade and the union of eggs and sperm in fertilization requires a water medium compensated for by heavy reliance on asexual reproduction in many species A diploid zygote mitotically divides forming a multicellular embro sporophyte while still attached to and dependent on the gametophyte The diploid fern sporophyte has conducting and supporting tissues amp is eventually nutritionally independent of the gametophyte although initially the sporophyte is parasitic on the gametophyte until it develops its own roots stem and leaves The prothallus withers and dies tophyta Do have horizontal underground rhizomes Dichotomous branching primitive characteristic occurring whenever the stem forks or branches it always divides into two equal halves in contrast when most plant stems branch one stem is more vigo rous becoming the main trunk Tiny round sporangia are found on its aerial stems d Prothalli gam etophyte grow underground where they symbiotically depend on fungi Most species are extinct with those surviving found in the tropic and subtropics nophyta Arthrophyta Horsetails most species are extinct with only a single genus Eguisetum 20 species surviving today Were the dominant plants 300 million years ago and grew as large as modern trees Fossilized remains together with those of other plants are the major source of presentday coal deposits Carboniferous Period Present day species the quotscouring rushesquot are widespread from the tropics to the Arctic on all continents except Australia grow mostly in wet marshy habitats Structure 1 a b e 2 3 4 5 Sporophyte usually less than 40 cm tall with true roots stems and small leaves Multiplebranched bushy structure of many species resembles a horse39s tail Deposits of silica in the epidermis give the plants a harsh abrasive quality Stems have conspicuous nodes that divide them into jointed sections a At each node there is a circlet or whorl of smaller secondary branches and a whorl of small scalelike leaves Some branches develop a conelike structure strobilus at their tip bearing spore sacs Homosporous type with the sporophyte dominating the sporic life cycle bio I lZOitrache ophytes 31805 BIOL 1120 REEDER HISTOLOGY amp ORGAN SYSTEMS I Tissues A De nition 1 A tissue consists of a few types of similarly structured and closely associated cells that are adapted to carry out speci c functions 2 Each kind of tissue is composed of cells with a characteristic size shape and arrangement B Tissue Types 1 Epithelial consists of cells tted tightly together forming a continuous layer or sheet of cells covering a body surface or lining a cavity or vessel within the body a Found in the outer skin layer linings of the digestive and respiratory tracts the lining of the kidney tubules and comprises exocrine and endocrine glands b Functions for protection absorption and secretion c Examples include simple 1 layer or strati ed layers of squamous cuboidal or columnar shaped cells also pseudostrati ed 2 Connective contains scattered cells embedded in an extensive intercellular substance secreted and maintained by the cells consisting of threadlike microscopic bers the intercellular substance varies from liquid plasma of the blood gel cartilage to bone a Functions to join together the other body tissues support the body and its structures protect underlying organs as well as provide the supporting framework of almost every organ b Examples include loose and dense connective tissues elastic adipose cartilage bone blood and lymph c Most abundant tissue 3 Muscle comprised of elongated cylindrical or spindleshaped cells usually referred to as a because of its length a Each ber contains many small longitudinal parallel contractile bers myo brils composed of the proteins actin and myosin b Muscle cells function by performing mechanical work via contracting and getting shorter or thicker body movement internal movement of materials blood pressure and material exchanges c Three types of muscle tissue are found in vertebrates 1 Cardiac walls of the heart 2 Smooth visceral walls of the digestive tract uterus blood vessels and certain internal organs 3 Skeletal makes up the large muscle masses attached to the bones of the body 4 Nerve composed of neurons specialized for conducting electrochemical nerve impulses and gm cells that support and nourish the neurons a Nerve cell processes include 1 Receiving signals from both the external or internal environment within body and transmitting them to the spinal cord and or brain for processing 2 Processing and storing information consciousness memory thought and directed movement 11 Organ Systems A De nition 1 An organ is a structure composed of two or more different kinds of tissues with a speci c function a blood vessel is composed of epithelial connective and muscle with nerve innervation biol l207histologyiorganisystemdoc 21 l09 Page 1 of 2 BIOL 1120 REEDER SEX DEVELOPMENT The sex of an individual depends on two processes 1 Sex determination genetic make up of an individual 2 Sex differentiation embryonic development of the reproductive system in utero 1 Genetic Sex A Determined by examining for the presence of either an XX or XY sex chromosomal complement a genetic female and genetic male respectively 1 Determination of genetic sex can be made from time of conception and throughout rest of a person s life span by looking for presence or absence of sex chromatin called a Barr Body and results from a process which occurs only in early female embryonic development amp inactivation a This chromatin material is found in somatic cells throughout the body of genetic females XX b Cell samples from buccal mucosa scrapings stained with dye that attaches to chromatin within nucleus examined under the microscope sex chromatin material seen just inside inner surface of nuclear membrane c The presence of sex 39 quot 39 quot 39 the true sex as female Determination for presence of Y chromosome made by staining nuclear chromatin with dye that uoresces under ultraviolet light examine under a microscope using ultraviolet illumination show a single uorescent spot within nucleus a This establishes the person as a genetic male E B Genetic sex is E at the time of conception and depends on which type of sex chromosome is contained within the fertilizing sperm X or Y Since half sperm contain an X and half a Y chances should be statistically equal that one or the other will fertilize the ovum however in practice this may not be true because factors other than chance play a role Examples a Ychromosomes are smaller than X and contain less genetic material therefore Y are less dense and may be more motile b May be differences in length of time sperm are viable so that time of ovulation could bias fertilization in favor of one sex over another 1 Alkaline pH at ovulation time favors Y 2 Acidic before ovulation favors X 3 Y chromosome carries holandric genes testisdetermining factor N N 11 Hormonal Control of Differentiation A First weeks of life embryo 1 Sex structures of both male and female remain identical and undifferentiated B Development 1 By 5th week of embryonic life the primordial from the beginning by the original gonad develops 2 Germ cells migrate from yolk sac and incorporate into developing testes if male 3 By 7th week sufficient differentiation has occurred so that the testes can be histologically identified in embryos with XY Interstitial cells or Leydig cells begin secreting androgenic hormone testosterone Testosterone induces further differentiation of primordial sex structures into those of male 9399 B101120SEXDEVELOPHUMAN 123001 BIOL 1120 REEDER Phylum Platyhelminthes 1 Characteristics Representatives are microscopically small or up to 7 meters in length believed to have a cnidarianlike ancestor free living and parasitic forms Parasitic forms ukes and tapeworms show specialization a suckers or hooks for holding on to the host b bodies are resistant to the host39s digestive enzymes cuticle c complicated life cycles utilizing one or more intermediate hosts followed by a definitive host d produce large numbers of eggs e of unneeded structures sense organs digestive system in certain members B Dorsoventrally attened bodies comm only called atworms to be distinguished from the nematoda roundworms parasitic forms from both groups are called helminths helminthology C No true segmentation D Bilateral symmetm with cephalization E Acoelomate mbody cavity F 3 germ layers tissuetriploblastic Ectoderm Endoderm Mesoderm mesenchyme G Epiderm is soft and ciliated g covered by cuticle thin noncellular external covering for protection with external suckers or hooks or both for host attachment H Welldeveloped digestive muscular nervous excretory and reproductive systems as compared to coelenterates due to well developed organs muscular pharynx eyespots simple brain complex reproductive organs protonephridia 1 Digestive if present a Incomplete mouth but no anus and usually much branched absent in tapeworms parasitic quotsacquot body plan gastrovascular cavity 2 Muscle contracting muscle fibers that produces changes in body shape and assist locomotion sheathlike layers arranged in circular longitudinal and oblique layers a Spaces between fibers and internal organs filled by soft mass of cells parenchyma acts as a hydrostatic skelton 3 Nerve contains pair of anterior quotgangliaquot primitive brain or a nerve ring and one to three pair of lengthwise nerve cords with transverse connectives ladderlike statocysts for equilibrium tactile cells and chemoreceptors 4 Excretory contains protonephridia ending in specialized collecting cells called ame cells with long waving cilia located between body cells pinocytosis into the ame bulb which then leads into a highly branched system of tubules a Waste materials and excess water pass into ame cells and are driven by cilia into excretory ducts leading to excretory pores on exterior surface 5 Reproductive a Sexes usually monoecious containing gonads testis and ovary with a duct system b Internal fertilization c Microscopic eggs d Development either direct or with one or more larval stages e Asexual in some forms I m skeletal circulatory or respiratory systems 1 Fluid in parenchyma around internal organs serves to distribute products of digestion and to carry oxygen gases diffuse across the moist epidermis of the body exterior acts as a hydrostatic skeleton 11 Representative classes Turbellaria freeliving atworms planarians Dugesia 1 Common to cool clear slow streams or ponds of freshwater avoid light by clinging to under surfaces of stones or logs in the water marine species as well 2 Two dark eyespots found dorsally on anterior end ocelli 3 Entire ventral surface covered by cilia for locomotion glides over a slime track 4 Midventrally the mouth opening is in an extensible muscular phagnx 5 Great powers of regeneration asexual mostly hermaphroditic crossfertilize into a comm on genital pore 6 Protonephridia with ame cells Trematoda ukes which are external and internal parasites 1 Characteristic thick cuticle protection with w cilia hooks and suckers BIOL l 120 REEDER TERMINOLOGY 3 l Taxonomy of the bryophytes 2 Taxonomy of the seedless vascular plants 3 Taxonomy of the seed plants 4 Terrestrial land plants ancestors 5 Nonvascular vs Vascular 6 Gam etophyte vs Sporophyte Zygotic Life Cycle Sporic Life Cycle True Alternation of Generations Gametic Life Cycle Isogam ous Anisogamous Oogam ous Significance of a pollen tube Homosporous vs Heterosporous Microspores vs Megaspores Seed as a significant innovation Advantages of an aquatic environment with challenges facing a terrestrial existence Advantages and disadvantages of a terrestrial environment Major plant innovations to a terrestrial existence Gametangia archegonia and antheridia Thallus Epiphytic Protonem a Rhizoids Sporangium Sphagnum Fronds S ori Prothallus Dichotom ous branching Carboniferous period Endosperm Pollination Gymnosperm characteristics Angiosperm characteristics Cyc ads Evergreens Ovulate or seed cone Staminate or pollen cone Microsporangium Megasporangium Micropyle Pollination uid Time period of conifer pollination and fertilization Flower significance to angiosperms Distinguishing features between angiosperms and gymnosperms Distinguish between monocots and dicots Cotyledon Vascular bundle Herbaceous vs Woody Annual Biennial Perennial Shoot system vs Root system Ground tissue system Vascular tissue system Dermal tissue system Plant organs L ignin Parenchyma Collenchyma Sclerenchyma Tracheids vs Vessel elem ents Sieve tube members BIOL 1120 REEDER Root Anatomy and Physiology 1 Root Function and Anatomy A Root Functions 1 Anchoring to provide a solid foundation for growth 2 Absorption water and dissolved minerals nitrate phosphate potassium sulfate from the soil into the xylem 3 Storage surplus sugars transported by phloem from the leaves stored as starch or sucrose 4 Unusual specializations a Aerial adventitious roots Prop roots develop from a vertical stem or branches and grow downward into the soil for extra support a more common in monocots corn and sorghum 2 Pneumatophores roots that grow upward in swampy or tidal environments to help attain sufficient oxygen a Have a well developed system of internal air spaces that is continuous with the submerged parts of the root allowing for gas exchange b Black mangrove white mangrove and bald cypress 3 Anchoring aerial roots of epiphytes grow attached to other plants that climb Anchors to bark a branch or other structure 4 PhotosEthetic aerial roots of epiphytes that also absorbs moisture b Contractile roots in addition to the normal roots of plants that can produce corms or bulbs underground stems or buds specialized for asexual reproduction 1 They grow into the soil and then contract shorten or collapse to pull the corm or bulb deeper 2 These roots are necessary because each succeeding year39s growth is on top of the preceding year39s growth bulbs and corms tend to move upward in the soil over time 3 More common in monocots some dicots and ferns 5 Relationships with other species a Graft as roots of certain trees birch and maple grow through the soil they may meet and grow together vascular tissues become connected 1 observed in over 160 species of trees Mycorrhizae mutual beneficial relationship with certain soil fungi 1 Transfer of materials between the two a Roots to fungus amino acids sugars Fungus to roots increases solubility of certain minerals phosphorus Nodules or swelling certain plant39s roots clover peas soybeans form an association with certain nitrogenfixing bacteria 1 Plants receive nitrogen requirements while bacteria receive photosynthetic products B Two Basic Types of Root Systems 1 Root depth and spread varies considerably among different species as well as among individuals of the same species a Corn depth of 25 meters and spread of 12 meters b Desert dwelling tamarisk trees depth of 50m 2 Taproot system a Consists of one main root with many smaller lateral roots coming out of it b Characteristic of dicots and gymnosperms dandelion hickory Most mature trees do not retain their taproots instead they have large shallow lateral roots from which other roots branch off and grow downward c Usually extend down into the soil to obtain water located deep underground 3 Fibrous system a consists of several to many roots of the same size developing from the end of the stem with many lateral roots branching of b Form in Plants that have a shortlived embryonic root 1 Initially originate from the base of the embryonic root and later from stem tissue adventitious organs that occur in an unusual location ie roots developing from stem 5 Examples include most monocots onion crabgrass corn Fibrous root systems are located close to the soil surface and are adapted to obtain rainwater from a large area 1 V ST 0 90 bi01 1207rootianatomylihysiology 3905 C Root Features 1 A root cap covers each root tip a many cell thick protective layer covering the delicate root apical meristem a As growth occurs cell replacement forms by root apical meristem b Helps to orient the root so that it grows downward 2 Root hairs are shortlived extensions of single epidermal cells located behind the growing root tip a They continually form in the area of cell maturation closest to the root ti b They are short and numerous and function to increase the root absorptive capacity by increasing root surface area contact with moist soil 3 Lack nodes and internodes and do not usually produce leaves or buds 4 4 Possess an outer protective covering epidermis or periderm a cortex for storage and vascular tissues for conduction D Root Vascular Tissue l Dicot herbaceous root buttercup primary growth only primary tissues only a Covered by a single layer epidermis b No cuticle in area of the root hairs in impede absorption c The cortex is primarily composed of loosely arranged parenchyma with large intercellular spaces and comprises the root bulk 1 Usually lack collenchyma because the soil provides support may contain some sclerenchyma 2 Functions for root storage mainly as starc 3 Large intercellular spaces provides for water uptake and aeration 4 d Inner cortex layer called the endoderm is controls the amounts and kinds of minerals that enter the xylem l A Casparian strip forms a special bandlike region on its radial and transverse walls a Casparian strips contain a fatty water proofing material called suberin e Just inside the endodermis is a single cell layer called the pericycle l the pericycle contains meristem atic parenchyma which give rise to multicellular lateral roots a Lateral roots originate in pericycle that is at the tip of an xylem arm breaks through several layers of root tissue endodermis cortex and epidermis and enters the soil 2 The pericycle also forms lateral meristems that produce secondary growth in woody dicots f The central cylinder of vascular tissues the is comprised of a starshaped xylem with phloem located in patches between the xylem arms 1 No pith due to the inner core of vascular tissue 2 Root xylem and phloem have the same kinds of cells as that found in stem vascular tissue39 roots typically have fewer support fibers 3 A ushaped vascular cambium is found sandwiched between the xylem and phloem 2 Monocot roots a Possess the same basic tissues as a dicot although exhibiting considerable variation b However the vascular tissues do not form a solid cylinder in the center instead there are separate alternating bundles of xylem and phloem arranged in a circle around the central pith c Lacks vascular cambium39 therefore no secondary root growth 1 Long lived monocots such as palms often have thickened roots due to expanded cortex 3 Dicot roots with secondag growth gymnosperms and woody dicots a The production of root secondary tissues by vascular cambium and cork cambium occurs some distance back from the root tips 1 Major tree roots may be massive with both wood and bark 2 Temperate climate root and stem wood exhibits annual rings Initially vascular cambium is sandwiched between primary xylem and phloem With secondary growth the vascular cambium39s growth will result in a continuous circular loop with secondary xylem to its inside and secondary phloem to its outside 1 The root increases in girth and the vascular cambium continues to move outward d Primary root tissues are crushed as root girth increases 1 Periderm replaces root epidermis as the cork cambium produces cork cells and cork parenchyma 2 Root cork cambium initially arises from the pericycle E Root Absorption Symplast Theopv 1 Water lost through the leaves is continuously replaced as soil water is taken up through the surfaces of root cells soil particles are coated with a microscopically thin layer of water in which minerals are dissolved films and capillary water 2 Root hairs establish an intimate contact with soil particles epidermal cells plus root hairs increase the root39s external surface area OFT biol l207rootpanatomylyhysiology 3905


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