Plant Unit Test for Biology 2
Plant Unit Test for Biology 2 BSC2011
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This 9 page Study Guide was uploaded by Kira Lowell on Tuesday February 9, 2016. The Study Guide belongs to BSC2011 at University of Florida taught by Douglas, Choe, DeMarco in Winter 2016. Since its upload, it has received 71 views. For similar materials see Integrated Principles of Biology 2 in Biology at University of Florida.
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Date Created: 02/09/16
Three Domains: 1. Archaea 2. Bacteria 3. Eukaryota Eukarya more closely related to Archaea Eukarya form a clade Eukarya + Archaea form a clade Endosymbiosis: Mitochrondria and chloroplasts have: o Own DNA o DNA consists of a single, circular chromosome o 2 membranes All eukaryotic cells have mitochondria; only some have chloroplasts Secondary endosymbiosis o With red algae = some dinoflagellates & streamenopiles (brown algaes) o With green algae = euglenoids Tertiary endosymbiosis o Some dinoflagellates (Gymnodinium) = red tide & ones that glow in dark whenever disturbed Example of lateral gene transfer Maximum parsimony principle—distribute branches of tree to group synapomorphies in simplest way Glaucophytes Microscopic freshwater algae Sister group to rest of Plantae Peptidoglycan in cell walls Red Algae Multicellular (most) Pychoerythrin = accessory pigment responsible for red color Chlorophyll a, not chlorophyll b Green Plants Chlorophytes, other “green algae”, Coleochaetophytes, Charophytes, Land Plants Monophyletic group Synapomorphies: o Chlorophyll b o Starch Green Algae NOT monophyletic group Chlorophytes, other “green algae”, Coleochaetophytes, Charophytes Chlorophytes—unicellular to large; phycoplast Other green algae—Spirogyra Streptophytes Monophyletic subset of green plants Coleochaeotophytes, Charophytes, Land Plants Synapomorphy + other green algae o Phragmoplast = parallel to mitotic spindle Synapomorphies of just streptophytes o Oogamy o Apical growth o Plasmodesmata o Parenchyma Land Plants Embryophytes; enclose egg in protective embryo Adaptations to life on land o Cuticle o Stomata o UV-absorptive pigments o Thick spore walls; sporopollenin = polymer that resists decay & dessication o Mutualistic associations with fungi = mycorrhizae o Multicellular gametangia (archegonia & antheridia) o Embryos o Alternation of generations Bryophytes Paraphyletic group Osmosis for absorption of water Require water for fertilization Nonvascular Swimming sperm with 2 flagella Lack true plant organs (roots, stems, leaves) Gametophyte dominant (photosynthetic & charistmatic generation) Sporophyte nutritionally dependent on gametophyte Mutualistic associations with fungi Epiphytic Liverworts o Most ancient o Flattened or leafy o Rhizoids = extensions of plant body; replace of roots o Elaters = dispersal of spores o Gemma cups = asexual reproduction (tiny pieces of liverwort) o Perianth = where archegonia are produced o NO stomata Mosses o Leafy o Stomata o Transport water externally through capillary action o Operculum = cap-like structure on distal end o Peristome teeth for spore dispersal (hygroscopic) o Perigonium & perichaetium (groups of antheridia and archegonia) o Sphagmum & dung mosses o Hornworts o Closest relative to vascular plants o Sporophytes look like small horns o Largest and most indendent sporophyte of the bryophytes o ONE chloroplast Tracheophytes = Vascular Plants Monophyletic group Lycophytes, monilophytes, gymnosperm, angiosperms Synapomorphies o Xylem with tracheids Tracheids—elongated thick-walled cells in xylem tissues that conduct water NOT alive at maturity Lignin Pits (holes; otherwise impermeable) o Phloem o Branched sporophyte independent of the gametophyte o True organs (roots, stems, leaves) Lycophytes (club mosses) Sister group to euphyllophytes Synapomorphies o Microphylls (single midvein & photosynthetic); evolve from sporangia Selaginella = become dormant state when conditions are dry Favor because positioned horizontally, allowing more surface area for collecting sunlight o Independent sporophyte and gametophyte Gametophyte reduce; still has antheridia and archegonia Euphyllophytes Overtopping growth Megaphylls Monilophytes o More complex, longer lived sporophyte = dominant o Homospourous = produce a single kind of spore o Horsetails Sister plants to ferns Equisetum Nonphotosynthetic reduced leaves Strobilus at top Silica o Ferns Sori = clusters of sporangia; covered by indusium Not actually a monophyletic grouping of organisms; only leptosporangiate ferns form clade Contain sporangia on both their leaves & modified leaves Annulus = assist in dispersal Leaf = frond; stalk = stipe stem underground Fiddleheads = young, coiled leaves Seed plants (Gymnosperms & Angiosperms) o Synapomorphies: Seed: seed coat (diploid), embryo (diploid), nutritive tissue (triploid or haploid) Woody secondary growth Secondary xylem accumulates toward the inside Secondary phloem does NOT accumulate; pushed to outside of tree & sloughed off Cork cambium & vascular cambium = lateral meristem Cork cambium from parenchyma—produce periderm Outer bark = all tissue external to vascular cambium (secondary phloem & layers of periderm) Heterospory = produce micro and megaspore Reduction in number of megaspores in sporangium—only mother cell undergoes meiosis producing 4 daughter cells Sporophyte dominance—protects and nourishes the microscopic gametophyte No water required for fertilization Gymnosperms o Naked seeds o Cycads Earliest gymnosperms Motile flagella Symbiotic relationship with Nostoc (N-fixing) Dioecious Produce male and female cone-like structures Seeds located on their leaves (often in strobili) Pollinated by beetles o Ginkgo One species: Ginkgo Biloba Female = offensive odor Dioecious Motile sperm Deciduous Live for well over 1,000 years o Gnetophytes Form a clade o Conifers Cone-bearing plants; most species-rich of gymnosperms Reduced megaphylls Resins—protective chemical that defends against insects and fungal infection Nonmotile gametes; wind pollination Megastrobilus (woody) & microstrobilus (herbaceous) Monoecious Some have modified cones that look like berries Angiosperms o Seeds surrounded by ovary o Synapomorphies Flowers—emerge from modified stems; flower parts emerge from modified leaves Fruits—matured ovary with ovules inside Reduced gametophytes—7 cells, 8 nuclei for female; male = 2 cells Double fertilization Production of triploid endosperm—nutritive tissue Ovules and seeds enclosed in carpel (ovary, style, stigma) Germination of pollen on a stigma Leaves with net venation Vessels in xylem (with fibers for structural support) o Stamen Male part Filament = stalk Anther = produce pollen o Carpel Stigma = sticky surface that serves to trap pollen grains Style = necklike portion of carpel that leads to ovary Ovary = holds ovules (embryonic seeds) Pistil = one or more fused carpels o Nonreproductive organs Sepals = generally green; protective function—calyx Petals = colored—corolla Calyx + Corolla = perianth Undifferentiated sepals & petals = tepals Receptacle = where floral organs are attached o Inflorescence = cluster of flowers o Pollination syndromes = sets of flower characteristics that are suited to certain animal pollinators Advantages of seeds Dispersal Nourishment No need for moisture/water for fertilization Dormany Differences between Gymnosperm Seeds and Angiosperm Seeds Nutritive tissue o Gymnosperms = haploid megamaetophyte o Angiosperm = triploid endosperm Seeds coats o Gymnosperms = derived from single integument o Angiosperms = derived from 2 integuments **Perfect flower = monoecious **Imperfect flower = dioecious Stomata & Xylem Function Primitive vascular plants o Stomata open when guard cells turgid (full of water = could stand to lose some to transpiration) o Stomata closed when guard cells flaccid/floppy Seed plants o Stomata open guard cells pump K and Cl IN; INCREASE water; become turgid = opening of stomata o Stomata closed guard cells allow K and Cl OUT; DECREASE water; flaccid/floppy = closing of stomata Transpiration, Cohesion, Tension Mechanism (Xylem) Transpiration—water lost to evaporation through open stomata Negative pressure at air-water interface; pull from more hydrated areas Water potential difference created at leaf Cohesion—sticking to itself Adhesion—sticking to other substances Capillary action—liquid flows in narrow spaces even in opposition to gravity Surface tension—water sticks to itself strongly at top of water column Translocation (Phloem) Primitive vascular plants o Only sieve cells for sugar transport Flowering plants o Sieve tube elements—long chains of sieve tubes (cells without ribosomes, vacuoles, nuclei) o Companion cell (with nucleus & ribosomes) = brain phloem o Sieve plates = connection for sieve tube members o No pores; xylem DOES have pores o Alive at maturity o Thin compared to xylem Pressure flow model o Positive pressure o Phloem sap flow from source to sink o Sugar actively loaded into companion cell & passes through plasmodesmata into sieve tube elements o Water potential decreases & takes up water from xylem through OSMOSIS turgor pressure o Sugar unloaded = pressure decreasewater flow back to xylem Prevention of self-fertilization Mechanistic block = anthers situated where impossible for pollinator to dump pollen on plant’s own stigma Temporal block = only release pollen when stigma is unreceptive to it Genetic block = self-incompatibility o Reject its own pollen o Prevented by biochemical block that prevents growth of pollen tube Plant Adaptations Climate o Annuals o Succulent leaves or stems o Tissues with high salt concentration (promote uptake of water) o Shallow roots o Modified leaves (spines) to reduce water loss o Thick cuticles & leaf epidermis covered in trichomes o Stomata located in sunken cavities o Light colors to reflect light o RuBisCO & photorespiration C3 is normal C4 = separate carbon fixation in different spaces: mesophyll cells and bundle-sheath cells CAM = separate carbon fixation in time; opening stomata during night & closing during day Low nutrient levels o Carnivory o Symbiotic relationships with nitrogen-fixing bacteria o Fungal associations = increase surface area Low levels of light o Rapid vertical growth o Lianas = woody vines that grow up to top of canopy & spread out o Epiphytes = grow on top of another plant Too much rain = drip tips Defenses against Herbivory Constitutive o Outer protective surfaces = thick cell walls, cuticle, suberized layers, bark, epidermis & epicuticular waxes o Trichomes o Laticifers o Sharp structures Thorns = modified stems Spines = modified leaves o Secondary metabolites = non-protein amino acids & other chemicals that are not used for basic cellular processes Induced o Pathogens contain Avr genes that code for elicitors o R genes in plant code for membrane proteins that are speicifc for certain elictors o Local response (hypersensitive response) Limited to area surround infection; apoptosis = programmed cell death Pathogenesis-related proteins (PR proteins) Phytoalexins = antibiotics toxic to pathogens Some PR proteins exit cell to warn other cells o Systemic response = throughout entire plant Increase resistance to wide range of pathogens Salicylic acid Causes plant’s enzymes to create small interfering RNA to prevent viral replication Alert other plants Plant Growth Apical meristems = primary growth Lateral meristems = secondary growth Phytochrome—perceives the interruption of dark periods Pfr = active state; responsible for cell responses Pfr converted to Pr at night lower ratio of Pfr to Pr at night Flower growth o Apical meristem ceases to produce leaves and stems = inflorescence meristem o Inflorescence meristems or floral meristems (one flower) o Shoot apical meristeminflorescence meristemfloral meristem Hormones Ethylene (gas) = fruit ripening Gibberellins o Stem elongation and cell elongation o Fruit growth and maturation o Seed germination Auxin o Elongation of target tissue o Phototropism o Gravitropism o Apical dominance o Formation of lateral and adventitious roots Monocots vs. Eudicots Monophyletic grouping; sister taxon to magnoliids Number of cotyledons o Monocot = single cotyledon o Eudicot = two cotyledon Leaf venation o Monocot = parallel veins o Eudicot = netlike veins (reticular venation) Stem anatomy o Monocot = vascular bundles scattered the stemcortex & pith indistinguishable o Eudicot = arranged in a ringcortex distinguishable from pith (cortex outside, pith inside) Secondary growth o More common in eudicots than monocots = wood in eudicots; herbaceous monocots
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