Exam 1 Study Guide
Exam 1 Study Guide 24010
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This 31 page Study Guide was uploaded by Amalia Cristiano on Sunday February 22, 2015. The Study Guide belongs to 24010 at San Diego State University taught by Berta in Spring2015. Since its upload, it has received 73 views. For similar materials see Biology 204 in Biology at San Diego State University.
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Date Created: 02/22/15
Biology 204 January 23rd 2014 Speciation Evolution by natural selection resulting in new species Arti cial Selection Selection of desired species by humans analogy to natural selection Adaptation A trait with a current functional role in the life of the history of an organism that is maintained and evolved by natural selection Can be beneficial to the survival of the organismspecies Morphological Adaptation An example would be harder beaks for birds to be able to better reach seeds Camou age Protective resemblance Mimicry Deceptive resemblance of a different organism so that the mimic benefits from the mistaken identity as seeming to be unpalatable or harmful Ex Larva resembling snakes misleading structures owersorchids Symbiosis Two species living in close contact Three types 1 Mutualism Both species benefit 2 Communalism One benefits one neutral moss 3 Parasitism One harmed one neutral moss Mutation can lead to coadaptation and coevolution Chapter 23 Microevolution Evolution of population level change in allele frequencies over generations Descent with Modification Descent pattern of DNA Genetics Dealing with heredity or transmission of and organism s traits Ultimate source of inheritable variation is a change in DNA Changes in DNA can be caused by mutation and genetic recombination Mutations Change in genotype other than recombination Three types 1 Point Change in DNA nucleotide 2 Chromosome Rearrangement of large piece of chromosomes gain loss inversion 3 Change in Chromosome Number Anaploidy change in chromosome number or less than the entire genome 2n62 Trisomy additional chromosome 21 results in Down Syndrome Polyploidy Evolution of chromosome number which doubles chromosome number 2n12 to 2n24 Genetic Recombination Natural shuf ing of all genes with meiosis and sexual reproduction Independent Assortment Aa and AA to AA to Aa Crossing Over Exchange of DNA between chromatid segments during meiosis Genetic Variation Source of most variation in sexual organisms new alleles combine Mutations Ultimate source of variation new genes and alleles Fitness Population or individual Measure of relative contributions of a given genotype to next generation allele genotype frequency in future generations divided by allele genotype frequency in previous generations First Generation 25 AA X 50 Aa x 25 aa 25 550 50 Second Generation 36 AA 48 Aa 36 54560 Fitness 6050l2 HardyWeinberg Equilibrium Frequency of geneallele does not change over time Aa gt AA Aa aa Pfrequency A qfreq a Pql 100 The HardyWeinberg Equilibrium is never met which leads to evolution Would only be possible with no mutations no migrations large population size etc Population Bottleneck Population crashes unique to individuals Founder Effect One or two individuals gone from large population Mating is random 1 harem breeding or 2 assortment 3 Sexual Selection All genotypes equally adaptive January 26 2015 HardyWeinberg essentially null hypothesis Selective Pressure agent or causative force that results in selection Ex Dark skin Selective pressureUV radiation UV increases sunburn and skin cancer in lighter skinned individuals E g for light skin selective pressureVitamin D synthesis Genetic Drift Change in genotype solely by chance effects Random Promoted by bottleneck and founder effect Founder effect ex Silverswords in Hawaii Evolution can occur by two major mechanisms Natural selection nonrandom Genetic Drift Random General Principle Selection dependent on the environment If environmental conditions change selective pressure changes Stabilizing Selection selection against the two extremes in a population 6 g birth weight in humans clutch size in birds Directional Selection selection for one extreme in a population against the other extreme e g pesticide resistance in insects antibiotic resistance in bacteria Disruptive Selection Selection for the two extremes in a population against the average forms 6 g limpets with two color forms Sexual Selection selection resulting in greater reproductive fitness Intrasexual Selection Within one sex usually males except in hyena populations Competition within Intersexual Selection Between two sexes preference by one sex for features of the other sex Usually female choice Sexual Selection Balance between survivorship decreased and reproductive potential increased Usually works against males Speciation the origin of a new species from a preexisting species Biological Species A set of naturally interbreeding populations that are genetically reproductively isolated from other sets of populations referring to sexually reproductive organisms Interbreeding within specieslineage Types of Speciation 1 Allopatricevolutionary change occurring in different geographic ranges Ancestral population divides each can undergo independent evolutionary change 0 Vicariancesplitting of an ancestral population into two 0 Dispersaltransfer of one or a few propagulesindividuals to a new region Unidirectional from North America to South America 2 Sympatric Speciation evolutionary divergence occurring in the same overlapping geographic ranges Rare in nature but may occur by January 28th 2015 Adaptive Radiation spreading of populations or species into new environments with adaptive evolutionary divergence Promoted by 1 New and varied niches provide new selective pressures 2 Absence of interspecific competition enables species to invade niches previously occupied by others ecological opportunity and vacant habitats with few competitors Macroevolution largescale evolution at and above species level Microevolution smallscale evolution at the population level Tempo of Speciation 1 Gradualism gradualistic speciation 0 Gradual stepbystep evolution 0 Ex Evolution of horses 2 Punctuated Equilibrium 0 Rapid evolutionary change during speciation followed by relatively long periods of stasis no change How can it occur 1 Founder principle or population bottleneck 2 Major environmental change new niches open up 3 Major genetic change a change in a gene that regulates development homeoticregulatory gene Heterochrony a change in the rate or timing of development Neotony a type of heterochrony Decrease in the rate of development Ex Many features of humans evolved by neotony Extinction opposite of speciation Over 99 of all species on Earth are extinct Exs Dinosaurs Dodo birds ammonites Extinction is a major driving force of evolution Opens up new niches by removing interspecific competition Phylogeny and the Tree of Life gt All life interconnected by descent Systematics Field of biology dealing with diversity and evolutionary history of life Includes Taxonomy Goal of taxonomy to determine evolutionary history of life 4 parts description identification nomenclature and classification Description assign features Characterfeature e g petal colors Character State2 or more forms of a character e g red or white petals Identi cation associate a known with an unknown using taxonomic key Nomenclature Naming according to a formal system Binomial species are two names Classi cation placing objects e g life into some type of order Taxon a taxonomic group pluraltaxa How to Classify Life Phenetic Classification based on overall similarities Those organisms most similar are classified more closely together Problem Can be arbitrary Phylogenetic Classi cation B ased on known inferred evolutionary history Advantage re ects pattern of evolution Not ambiguous Cladogram or Phylogenetic Tree representation of the history of life Ingroup group studied Outgroup group not part of ingroup used to root tree Apomorphy derived trait A new derived feature Scalesancestral featuregtgtgtfeathers derived feature Presence of feathers is an apomorphy for birds Taxa are grouped by apomorphies apomorphies result in evolution Taxa sharing apomorphies should be grouped together because they went through the same evolutionary history Principle of Parsimony The tree having the fewest steps evolutionary changes is the one accepted Okham s Razor the simplest explanation with fewest number of ad hoc hypothesis is accepted Other methods of phylogeny construction maximum likelihood and Bayesian analysis DNA sequence datamost important January 30th 2015 Hierarchical Ranks Domain Kingdom Phylum Class Order Family Genus Species Maximum Likelihood or Bayesian Analysis uses probabilities Advantage can use evolutionary models DNA sequence datamost important Each nucleotide positioncharacter Character statesspecific nucleotide Homology Similarity resulting from common ancestry Exs The forelimb bones of a bird cat and bat Homoplasy analogy Similarity not due to common ancestry Reversal Loss of a new apomorphic feature resembles old ancestral old feature Convergence parallelism gain of new similar features independently Legless Lizards and Snakes examples of reversal Within tetrapods Loss of derived feature forelimbs Examples of convergence relative to one another Independently evolved Orthology Genes homologous Paralogy Genes not homologous Monophyletic Group a group consisting of a common ancestor all the descendants of that common ancestor Relationship recency of common ancestry ie taxa sharing a common ancestor more recent in time are more closely related than those sharing common ancestors more distant in time EX Fish more closely related to humans than sharks Paraphyletic Group Consist of common ancestor but not all descendants Paraphyletic groups are unnatural distort evolutionary history and should not be recognized Did humans evolve from apes We share unique human features We also share features With other apes and other animals plants fungi etc Humans didn t evolve from apes humans apes Importance of Systematics and Evolution 1 Foundation of biologystudy of biodiversity 2 Basis for classification of life 3 Gives insight into biological processes adaptation to environment 4 Can be aestheticallyintellectually pleasing Bacteria and Archaea Three major domains of life bacteria archaea and eukarya Bacteria and Archaea prokaryotes before nucleus Bacteria and Archaea similar to one another in that 1 DNA circular chromosome or nucleoid sometimes smaller plasmids 2 No membranebound organelles lack nucleus endoplasmic reticulum mitochondria chloroplasts golgi bodies 3 70 S ribosomes 80 S in eukaryotes 4 No cytoskeleton therefore no mitosis ALL ANCESTRAL FEATURES Thylakoids membrane systems With photosynthetic compounds February 26 2015 Prokaryote motility Flagella Internal fibrils Gliding motion Gas vesicles Some bacteria have fimbriae attachment pilifunction in adhesion Prokaryote Cell Walls Most bacteria and archaea have a cell wall Bacteria cell wall contains peptidoglycan polymer of amino sugar units Archaea cell walls lack peptidoglycan also differ in membrane chemistry RNA polymerase tRNA structure Gram stain separates Bacteria into 2 groups Grampositive pick up Violet dye have thick outer peptidoglycan cell wall layer Gramnegative don t stain Violet only pink counterstain have thin peptidoglycan layer have outer membrane lipopolysaccharides can have outer capsule tend to be more virulent Prokaryote Reproduction 0 Most asexual fission very rapid cell division 20 minutes 0 A few exchange genetic material but no meiosis Starting with 1 bacterial cell With no limit to cell diVision at 20 minutes per division 272472X1021 4720000000000000000000 after only one day ca no grains of sand on earth Therefore bacteria can evolve relatively quickly by rapid reproduction amp mutation 9 million per day in E coli of 1 human gut Genetic recombination in Bacteria amp Archaea 1 Transformation uptake of foreign DNA from outside into cell then homologous DNA exchange 2 Transduction phages bacteriophages which are Viruses that infect bacteria transfer bacterial genes from one host to another 3 Conjugation DNA transferred lway from one bacterial cell to another Sex pilus pulls one cell to another Mating bridge allows transfer of DNA plasmids or parts of chromosomes Plasmids small circular pieces of DNA Fplasmid allow mating bridge Fertility Rplasmid allow antibiotic Resistance Prokaryote Metabolism 0 Require oxygen aerobic Don t require oxygen anaerobic obligate anaerobes 02 poisonous can t survive in its presence facultative anaerobes can live in presence of 02 but don t need it Prokaryote MetabolismNutrition 1 Energy needed 2 Source of carbon needed Photoautotrophs photosynthetic energy source is light carbon source is C02 Found in some Bacteria Archaea amp Eukarya e g plants E g Cyanobacteria use chlorophyll and produce oxygen byproduct 6C02 6H20 gt C6H1206 602 quotoxygenicquot photosynthesis Changed atmosphere of earth ca 23 billion years ago from anoxic to oxygenrich Photoautotrophs photosynthetic energy source is light carbon source is C02 Other bacteria use other pigments bacteriochlorophyll retinal produce e g sulfur as byproduct Photoheterotrophs energy source is light carbon source is organic compounds from other organisms Found in some bacteria e g Rhodobacter purple nonsulfur bacteria Chemoautotrophs energy source is oxidation of inorganic compounds e g ammonia nitrite H2 HS Sulfur carbon source is C02 Found in some Bacteria many Archaea Including Archaea from deepsea vents Chemoheterotrophs energy source and carbon source is highenergy organic compounds from other organisms Found in Bacteria Archaea and Eukarya saprobes dead decaying organic material symbionts pathogens parasites on liVing organisms commensalisticmutualistic liVing onWithin liVing organisms Nitrogen xation N2 atmospheric nitrogen gt NH3 NH4 Rhizobium bacterium lives symbiotically with legume roots enzyme nitrogenase Other Nitrogenfixing bacteria N2 atmospheric nitrogen gt NH3 ammonia nitrogenase E g Some Cyanobacteria bluegreens Cyanobacteria N2 fixers symbiotic relationship with Azolla an aquatic fern important in rice production symbiotic relationship With some cycads Pathogenic diseasecausing bacteria Invasiveness ability to multiply Within host E g anthrax has high invasiveness Toxigenicity ability to produce toxins Eg diphtheria has high toxigenicity Endotoxins lipopolysaccharides in outer membrane of some bacteria released when bacteria lyse burst open Eg Salmonella E coli toxic strains Exotoxins proteins secreted to outside by living bacteria very toxic E g tetanus botulism cholera plague anthrax syphilis a spirochaete bacterium a sexually transmitted disease Staphylococcus staph infections Streptococcus e g form of pneumonia strep throat chlamydia very tiny bacteria cause of some sexually transmitted diseases pneumonia etc Actinomycetes form branched filaments resembling fungi tuberculosis Mycobacterium tuberculosis Streptomyces source of streptomycin many other antibiotics some even occur inside plants Mycoplasmas lack cell walls some among smallest organisms some cause diseases animal and plant Endospore protective resting phase of some spp heat drought UV light resistant can remain dormant for very long periods some pathogenic bacteria form endospores eg C botulinum causes botulism Mutualistic symbiotic bacteria 1 Intestinal bacteria eg E coli in humans 100 trillion in our guts 10X no human cells 35 lbs Fecal Microbiont Transplant FMT new area of active research Can be effective against Clostridium di icile lifethreatening diarrhea and on Chron s disease chronic in ammation of the gastrointestinal tract autoimmune response and colitis 2 Bacteria digests cellulose in gut of Trichonympha a ciliate that lives inside the gut of termites 3 Bioluminescent bacteria fish Useful Bacteria Bioremediation remove pollutants e g oil plastics DNA Sequencing Thermus aquaticus thermophilic chemoautotropic bacterium source of taq polymerase used in sequencing reactions Genetic engineering synthesize hormones antibiotics ethanol Archaea Many live in extreme environments thermophilic heatloving acidophilic acidloving sulfur loving e g hydrothermal vents methanogenic methaneproducing release 2 billion tons of methane into atmosphere each year 13 from guts of grazing animals eg cows halophilic saltloving Deep sea hydrothermal vents rich in HS hydrogen sulfide Temperature at vent gt400 C but just around 4 C nearby Chemoautotrophic Archaea use HS as energy source live symbiotically With animals e g giant tube worms Eukaryotes Loss of cell wall enabled endocytosissubstances taken up by membrane invagination Protists Protista Protists sometimes recognized as a Kingdom but is a highly Darathletic group Endoplasmic Reticulum Site of chemical reactions protein synthesis Lysosomes digestion Peroxisomes Chemical reactions Endosymbiosis One cell living Within another ancestral engulfment of bacterium by a eukaryotic cell origin of mitochondria and chloroplasts Some lateral transfer of DNA occurred between the DNA of chloroplasts amp the nucleus E g RuBisCo Ribulosebisphosphate carboxylase catalyzes C02 fixation in photosynthesis small subunit genes in nuclear DNA large subunit genes in chloroplast DNA Mitochondrion functions in respiration oxidative phosphorylation DiplomonadsParabasalids lack or reduced mitochondria Mitochondrial lossreduction thought secondarily derived Diplomonads intestinal parasite cause of giardiasis Parabasalids sexually transmitted either malefemale genitalia Chlorophyll a and b slightly different chemically Storage paramylon Kinetoplastids include trypanosoma cause of sleeping sickness 80 chance of death if not treated kills 3 million livestock each year Typically in tropical areas Rhizaria Two major groups Foraminifera Radiolarians Radiolarians Foraminifera Some secrete shells of silica radiolarians or calcium carbonate foraminiferans Feedingquotaxopodiaquot or quotpseudopodiaquot that extrude from shells Fossilized skeletons make up vast fossilized deposits e g limestone deposits of foram s used in geological dating of sediments Alveolates Monophyletic group Many have alveoli membraneenclosed sacs to periphery of cells Ciliates no cell wall cilia short numerous have a 92 pattern Dino agellates chloroplasts chlorophyll a amp c storage starch alpha14glucopyranoside cell walls absent or in plates thecae agella 2 in grooves important components of plankton primary producers some cause red tide harmful algal blooms natural or humanaccelerated eg Karenia brevis can produce neurotoxins can also deplete oxygen fish kills harm to birds marine mammals can be passed up food chain to humans e g toxic oysters other shellfish some bioluminescent luciferin luciferase Ampicomplexans Sporozoans Include Plasmodium 4 spp direct cause of malaria Requires intermediate host eg mosquito Anopheles spp ca 24 spp infect humans Invade and lyse burst red blood cells in cycles Cryptosporidium ampicomplexan that can be a human intestinal parasite can infect water supplies Sydney Australia 1998 Symptom diarrhea Stramenopiles Monophyletic Group Stramenopile means straw hair referring to agella Most have heterokont cells with 2 agella 1 whiplash smooth 1 tinsel hairy hairs tubular Oomycota Water Molds Formerly classified as Fungi Oon egg mycota fungus Most are saprobes heterotrophs feeding on dead decaying matter e g Saprolegnia Some are parasites heterotrophs feeding on liVing organisms E g Phytophthora infestans Potato Blight Cause of Irish Potato Famine ca 1845 1 million died 2 million emigrated to US Filaments long chains of tubular cells cell walls with cellulose Coenocytes many nuclei per cell Can reproduce asexually or sexually Chromobionta Brown Plants 0 Chloroplasts with chlorophyll a amp c photosynthetic accessory pigments carotenoids yellow fucoxanthin brownish storage compound chrysolaminarin 11 beta 13 1 beta 16glucopyranoside oil 0 Include Coccolithophore phytoplankton very important primary producers Brown Algae Phaeophytes Brown or greenbrown color fucoxanthin accessory pigment 0 Some complex structure thallus Some with alternation of generations life cycle 0 Cell wall algin alginic acid Used as emulsifier in ice cream soups cosmetics etc emulsifierkeeps ingredients from separating Used in dentistry tooth impressions Harvesting of kelp Macrocystis in San Diego Diatoms 2 forms centric and pennate Cell walls in 2 interlocking halves composed of silica Economic Importance of Diatoms Important components of phytoplankton as primary producers Diatomaceous earth fossilized mined remains of diatom cell walls Uses filtering polishing stabilize dynamite y repellant eg for livestock Diatoms can produce neurotoxins too 0 Pseudonitzschim if too much Nitrogen from water pollution Will produce excess domoic acid a neurotoxin mimics glutamic acid affects seals permanent short term memory loss Red Algae RhodobiontaRhodophyta Chloroplasts chlorophyll a amp d accessory pigments phycobilins amp phycocyanins resemble blue green bacteria Cyanobacteria storage compound oridean starch alpha 14glucopyranoside With many 16 branches All cells lack agella Cell walls carrageenans agar some outer calcium carbonate layer Red Algae can have complicated life cycles e g two diploid phases Economic Importance of Red Algae 0 Some edible Dulse Nori used to wrap sushi Some harvested for carrageenans amp agar carrageenans used as emulsifiers in foods e g ice cream amp other products agar used as microbiological culture medium Amoebozoans quotamoeboidsquot now thought to be close to fungi amp animals Unikonts pseudopodia armlike extensions of cytoplasm phagocytosis type of endocytosis using pseudopodia surround and engulf prey contractile vacuoles in some remove excess water Some amoeba entamoebae are parasites Eg Entamoeba histolytica Cause of amoebic dysentery spread by contaminated food water eating utensiles causes over 100000 deaths per year 3rd leading cause due to eukaryotic parasites Amoebozoans Slime Molds Formerly like water molds classified as fungi Acellular slime molds One huge multinucleate cytoplasmic mass called a plasmodium don t confuse With genus Can slowly move over a substrate and digest it Exhibit cytoplasmic streaming outer cytoplasm uid motile Feed by phagocytosis like a huge amoeba Cellular slime molds composed of cells mxyamoebae that aggregate together into SLUG pseudoplasmodium Ancestral type of multicellularity February 9 2015 Fungi most biomass is underground as hyphae Importance of Fungi decomposers mutualistic symbionts With plants parasitespathogens economically useful food medicine breadalcohol Leafcutter ants in tropical America culture a fungus and eat it that decomposes leaves symbiotic relationship ParasiticPathogenic ringworm tanea athlete s foot certain pneumonia s candida yeast infections plant diseases corn smut Wheat rust Heterotrophs Chemoheterotrophs feed by absorptive nutrition They secrete digestive enzymes that break down food then absorb digested food Cell walls contain chitin Some fungi are unicellular most multicellular or coenocytic hyphae Mycelium body of fungusmass of hyphae 5 groups of fungi 1 Chytridiomycetes 2 Zygomycetes 3 Glomeromycetes 4 Ascomycetes 5 Basiliomycetes Deuteromycetes Imperfect Fungi fungi with no sexual structures now classified into other groups with DNA analysis Chytrids aquatic with agellated cells unicellular or multicellular some have alternations of generations haploid and diploid phases Zygomycetes coencocytic septate hyphae most produce sporangiophores which bear sporangia which produce asexual spores Rhizopus black bread mold reproduce sexually Glomeromycetes mychorrhizal root of vascular plant Symbiotic association mutualistic between a fungus and the roots of a plant Essential for growth in many plants They help a plant to absorb water and mineral nutrients such as phosphorous and the fungus obtains highenergy carbohydrates from the plants Can form networks interlinking different trees of the same or different species Ascomycetes hyphae with cells haVing two nuclei dikaryotic hyphae which is an apomorphy of both Glomeromycetes and Ascomycetes Ascus sac containing walled spores ascospores Sexual reproduction 2 major groups Hemiascomycetes no fruiting structure and Euascomycetes fruiting structure Hemiascomycetes yeast saccharomyces sugar fungi reproduce asexually by budding unequal cell diVisions one smaller one bigger anaerobic fermentation Glucosegtgtgtgtethanol and C02 yeast used in breadalcohol production C02 causes bread to rise important in molecular biology Euascomycetes have fruiting bodies called ascocarps Some economically significant parasites February 11 2015 Ergot Infects ryeoutbreak in Europe Caused hallucinations madness convulsions etc Medicinal Value 1 Ergonovine used to induce labor 2 Ergotamine used to treat migraines LSD derived from secondary compounds of Ergot Euascomycetes Some are edible Morels Truf es subterranean pigs can be trained to find them Worth a lot of money Penicillium Mold that produces the antibiotic penicillin discovered by Fleming Also used as cheese avoring brie bleu Aspergillus Used in production of soy sauce and other avorings Used in production of sake breaks down starches to sugars Green Plants Chromobionta Chloroplasts chlorophyll a and b Storage product starch Thylakoids in stacks called grana Cell Walls composed of cellulose Polymer of glucose 2 forms of glucose alpha and beta forms Starch 14 linkage of glucose monomers Cellulose beta form of glucose Cellulose Cell Wall Made of cellulose microfibrils Green Algae A paraphyletic group Unicellularmulticellular Colonial Filamentous Thalloid Life cycle variable haplontic diplontic haplodiplontic Many green algae have agella Oogamy evolution of the egg Egg large nonmotile gamete The Land Plants Embryophyta First colonization of plants on land approx 400 mil Years ago Now dominate the Earth Haploid gametophyte 1 set of chromosomes Diploid sporophyte 2 sets of chromosomes Haplodiplontic Life Cycle Altemation of Generations Found in several groups of algae as well GametophytegtgtgametesgteggspermgtgtfertilizationzygotegtgtEmbryoimmature sporophytegtgtSporophytegtgtsporangium meiosisgtgtsporocytesgtgtspores Parenchyma 3D mass of cells Apomorphy for all land plants Generalized cell type of ground tissue system functions in metabolismcell growth Cuticle Protective layer on outside of outer layer of cells epidermis Inhibits water loss Antheridium Male reproductive organ of gametophyte Produces sperm Archegonium Female reproductive organ of gametophyte Produces egg Prevents against water loss dessication Only occurs when dewywet outside cells so sperm can swim Liverworts Hepaticae 2 basic forms thalloid and leafy Thalloid at mass of tissue Leafy individual at structures that resemble leaves Gemmae gemma cup asexual reproductive structure Stomates apomorphy of Homworts Functions in gas exchange C02 in H20 and 02 out Controls loss of water vapor Hornworts Always thalloid Have cylindrical sporophyte Mosses All leafy Specialized conducive cells Gametophyte longlived dominant Sporophyte shortlived nutritionally dependent on gametophyte Sphagnum Peat moss Leaves have tiny pores that retain water Plants make ground water acidic from extensive bogs Secrete acid into environment inhibits growth of fungibacteria Possible adaptation Peat partially decomposed Sphagnum Used in potting media Used as fuel Vascular Plants Tracheophytes A land plant With vascular tissue xylem and phloem Functions in conduction of watersugar Sporophyte dominant and independent Roots shoots and supportive tissue Rhynia One of earliest vascular plants Lacked roots Xylem H20 and mineral conductive tissue Composed of l Tracheids no perforation plates 2 Vessels Perforation plates in end walls Phloem sugar conductive tissue 1 Sieve Cells 2 Sieve Tube Members Both With calloselined pores vascular tissue analogous to veinsvessels in humans February 16 2015 Apical Stems Where reproduction takes places Shoots grow aerially Photosynthetic and conductive part Stem leaves Stem support conduction sometimes storage Leaves maj or photosynthetic organs Region of Cell Elongation Region of Cell Differentiation specialization Bud immature shoot Mature Bud identical to parent shoot Develop into branches or reproductive organs Roots Anchorage Absorption water minerals Storage in some Roots Differ from Stems in That Root cap Root hairs No external primordial Oxygen is required by plants Many roots mycorrhizal Tissue Systems Dermal Outside protects from damage dessication pathogens Vascular xylemphloem Conduction of water minerals Ground metabolism photosynthesis Parenchyma Lignified Fibers Lignin hard substance secreted within secondary cell wall Secondary Cell Wall extra wall layer between primary cell wall and plasma membrane in some plant cells adds structural support found in tracheids vessels fibers all dead cells allows for evolution of supportive plant cell called sclerenchyma fiber Lycophytes Extinct lycophytes lycopods were tall trees make up some of coal deposits Lycophytes alive today are small all have microphylls Lycopodium spores used in original camera ash powders even some fireworks Equisetcophytes scouring rusheshorsetails whorled microphylls sporangium spores with elaters horsetails have whorls of lateral branches Psilophyta whisk broom no roots macrophylls or enations no veins dichotomously branched green stems synangium bifurcate appendage forked Pteridales leptosporangiate ferns Megaphylls large leaves with multiple veins Leptosprangium One cell thick Spores ejected Sorus group of leptosporangia indusium ap covering sorus Aquatic ferns Azolla Mosquito Fern symbiotic relationship with blue green bacteria seeded in rice paddies for nitrogen fixation Seed Plants spermatophytes Eustele Eustele single ring of vascular bundles Vascular bundle strand of xylem and phloem Wood Adaptive significance Added great structural support Allowed plants to grow m have more extensive branches increased fitness Evolution of Wood Wood originates from vascular cambium Vascular cambium ring of cells that result in lateral growth secondary xylem wood to inside secondary phloem inner bark to outside Cork cambium grows to outside forms outer bark protective Seed embryo immature sporophyte surrounded by nutritive tissue enclosed by a seed coat Adaptive significance of seeds 1 Protects embryo 2 Nutrition of embryo 3 Disperses embryo wind water animal dispersal 4 Dormancy mechanism seeds can remain dormant for many years until conditions right for germination How did seeds evolve 1 Heterospory the evolution of two types of spores male spores microspores female spores megaspores 2 Female gametophyte develops inside spore wall retained on sporophyte not released 3 Protective layer integument seed coat develops around seed Female gametophyte is attached to and nutritionally dependent upon sporophyte Just the opposite of nonvascular plants e g mosses Male gametophyte also develops within spore wall immature male gametophyte pollen grain Cycads Ancient lineage 300 million years old 0 Short trunks 0 Compound leaves 0 Most have cones male amp female Dioecious separate males amp females 0 Swimming sperm ancestral retention Cone shoot system bearing sporophylls sporophyll modified leaf that bears sporangia seeds Cones can be male with microsporophylls or female with megasporophylls Ginkgo 0 One species Ginkgo biloba 0 Native to China a living fossil 0 Tree 0 Leaves fanshaped dichotomous venation Dioecious Swimming motile sperm Gnetales Three genera one Ephedra desert shrub worldwide Mormon Tea source of ephedrine 0 Simple opposite leaves 0 Male amp female cones monoecious or dioecious 0 Nonmotile sperm Conifers 0 Trees 0 Simple leaves Most monoecious female amp male cones on same individuals 0 Nonmotile sperm Examples 0 Pine Cypress Spruce Hemlock 0 Fir Redwood 0 Giant sequoia Cycads Ginkgo Gnetales amp Conifers long time period between pollination transfer of pollen to ovule and fertilization union of egg amp sperm 0 Up to a year or more Flowering Plants Angiosperms 0 Largest group of Land Plants 0 Most important economically Apomorphies Flowers Carpels Fruits Double fertilization with triploid endosperm Specialized conductive cells U PP Ni Flowers What is a ower Shoot system bearing modi ed leaves Perianth Calyx sepals green protective Corolla petals colored attractant Stamens male Carpels female Flower pollination transfer of pollen to ovule Animal pollination Ancestral for Angiosperms Much m efficient means of transporting pollen All Gymnosperms are wind pollinated Some Angiosperms secondarily wind pollinated Strategy of animal pollination Attractant Visual large or brightly colored perianth Olfactory smell sweet g rotten fetid odor Reward Usually nectar or pollen Rarely waxes oils Pollination Mechanisms Insects Bees Butter iesMoths Flies Birds Bats Water Wind 2Carpels Carpel conduplicate megasporophyll Conduplicate folded Megasporophyll female leaf bearing seeds Carpel totally encloses ovulesseeds Carpels can fuse together Gynoecium all female parts Pistil ovary style stigma Pistil can be one carpel or many Function of Carpel l Protects young seeds 2 Site of pollen germination Can induce selfincompatibility reactions 3 Fruits Selfincompatibility Pollen Will not germinate on genetically similar individuals Promotes outcrossing Fruits Fruit mature ovary plus accessory parts Function seed dispersal Fruit types dry dispersed mechanically by Wind water etc eshy dispersed by animals Double fertilization in Angiosperms Pollen produces 2 sperm cells sperm n egg n gt zygote 2n sperm n 2 polar nuclei n gt endosperm 3n Triploid endosperm is nutritive tissue in seeds of Angiosperms Extra set of genes may help in 1 rapid development 2 increase genetic variation Gymnosperms Fertilization occurs long after pollination Seeds mature slowly 12 years Angiosperms Fertilization occurs soon after pollination Seeds produced rapidly Selective advantage e g annual herbs Specialized conductive cells Most Angiosperms have vessels Specialized in having perforation plates All Angiosperms have Sieve tube members with sieve plates bigger pores in end walls Vessels and sieve tube members more efficient in water sugar conduction Angiosperm Classification Old classification Dicots 2 cotyledons seed leaves Monocots 1 cotyledon Monocots monophyletic Monocot apomorphies stem an atactostele many scattered vascular bundles wood lost Examples Palms Orchids Irises Grasses etc Dicots paraphyletic Features that defined Dicots are primitive not apomorphies Eudicots monophyletic Eudicot apomorphy Pollen tricolpate 3 apertures All other Angiosperms Pollen has 1 aperture Eudicots include most angiosperms Roses Legumes Daisies Oaks etc Plant Growth in Angiosperms Plants have hormones Substances produced in one part of body transported to another part where it has a physiological effect binds to receptor triggers response in nearby cellstissues Auxin Indole Acetic Acid IAA 1 Functions in phototropism movement toward light Auxin concentrated on dark side Induces cell expansion elongation 2 Functions in gravitropism movement relative to gravity Shoots negatively gravitropic Roots positively gravitropic In both auxin concentration induces cell expansion elongation Acts by loosening cellulose microfibrils of cell walls Causes cell expansion 3 Functions along with cytokinens in apical dominance Auxins produced by apical meristem Inhibits growth of lateral branches If apical meristem damaged auxin production stops No longer inhibits lateral branch growth lateral buds gt branches 4 Promotes secondary growth amp wood production Cytokinins 1 Promote cell division 2 Stimulate bud formation gt lateral branches 3 Inhibit stem elongation Balance of cytokinins amp auxins gt many plant growth processes Gibberellins 1 Function in seed germination Embryo releases gibberellins Causes aleurone layer in seed coat to release enzymes alphaamylase break down starch in endosperm to sugars e g maltose 2 Fruit development Seedless fruit crops e g grapes may be artificially sprayed with gibberellins make fruits bigger 3 Stem growth elongation Induce bolting elongation of owering stem of some plants Ethylene a gas Involved in fruit ripening applied commercially to ripen some fruits Apical hook some Eudicot seedlings ethylene inhibits growth on inside of hook protects apical meristem Phytochromes Photoreceptor proteins Two forms P r absorbs red light converted to P fr P fr absorbs far red light converted to P r Involved in seed germination Only P fr form after exposure to red light will cause seeds to germinate Transport of water and sugar in plants Transpiration evaporation of water from leaves moves water molecules in xylem up from the roots Cohesion of water molecules for one another allows continuous water column to be maintained Water follows a water potential 1 gradient affected by pressure gravity and solute concentration from high to low Water potential at the leaf is very low 10 to 100 MPa becoming increasingly higher at the roots 06 MPa Tension of water column is maintained by water ow and cohesion How is sugar transported Movement occurs from a region of high concentration to low concentration sugar source Where sugar produced e g from leaf or by breakdown of starch to a sugar sink Where it is utilized Water entering sieve elements causes positive osmotic pressure greatest Where sugars are most concentrated Thus sugars move by pressure ow from a region of high concentration high pressure to a region of low concentration low pressure Osmosismovement of water across a membrane from low to high concentration of solutes results in increased osmotic pressure Pressure Flow Movement by osmotic pressure Within sieve elements from high sugar concentration to low sugar concentration sugar source Where sugar produced e g from leaf or by breakdown of starch to a sugar sink Where it is utilized
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