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  1. advantages of living on land for plants (4)
    • 1) bright sunlight unfiltered by water/plankton
    • 2) atmosphere has an abundance of CO2
    • 3) soil is rich in mineral nutrients
    • 4) initially there were few herbivores and pathogens
  2. closest living relatives to land plants (of the green algae):
    charophyceans; DEEP GREEN provided DNA evidence support charophyceans as closest algal relatives to land plants; development of sporopollenin prevented the zygote from drying out
  3. Megaphylls
    found in vascular plants (NOT lycophytes) and are leaves with a highly branched vascular system; precursors to leaves?
  4. evolution of land plants (oldest to youngest)
    • non-vascular bryophytes (liverworts, hornworts, mosses)
    • then all the rest are vascular:
    • lycophytes (club mosses, spike mosses, quillworts)
    • pterophytes (ferns, horsetails, whiskferns)
    • then come gymnosperms and then angiosperms
  5. bryophyte
    COME BACK TO slide 27 not important enough
  6. multicellularity evolved ___________ between plants and animals
    INDEPENDENTLY; they have different ways of developing
  7. self renewal
    stem cell divisions create two daughter cells: one cell forms a specialized cell while the other PRODUCES ANOTHER STEM CELL (called self renewal)
  8. Steward Carrot Experiment
    grew a whole new carrot from pieces of an already formed one; single nonreproductive carrot cell developed into a mature carrot plant, which was a genetic duplicate of the 1st plant
  9. Birnbaum arabidopsis experiment
    showed that specialized root cells regenerate even when the root meristem is removed; shows that most if not all plant cells are totipotent?
  10. dermal tissue (epidermis)
    single layer of tightly packed cells that covers and protects all young parts of the plant; specialized epidermal cells = roots hairs (single epidermal cell), trichomes (hairs) on leaves (single elongated epidermal cell), and stomata (guard cells) on leaves (gas exchange, let CO2/O2 in and out)
  11. each organ (ex: leaf, stem root) is made of 3 types of tissues:
    • outer layer = dermal (ex: epidermis)
    • middle layer = ground tissue
    • inner layers = vascular tissue
  12. apical meristems
    responsible for primary growth (enables the plant to grow in length); located at tips of roots and buds of shoots; cause vertical growth
  13. lateral meristems (vascular/cork cambium)
    add thickness to woody plants through secondary growth; contributes to lateral growth (stem widening); vascular cambium adds wood (secondary xylem) and cork cambium replaces epidermis with thicker/tougher periderm
  14. flower formation involves a phase change from _________ growth to ____________ growth
    vegetative to reproductive; it's triggered by environmental and internal signals
  15. a flower is:
    a specialized type of shoot with 4=FOUR rings (whorls) of modified leaves; sepals and petals are sterile, while stames and carpels are fertile

    • Sterile floral organs (whorls):
    • 1) Sepals: enclose the flower
    • 2) Petals: colored and attract pollinators

    • Fertile sporophylls (whorls):
    • 1) Stamens (male): make pollen [contain anther/filament]
    • 2) Carpels (female): make ovules [contain stigma, style, ovary]
  16. ABC model of flower formation
    • identifies how 3 types of genes direct the formation of the hour types of floral organ
    • so from outer to inner whorl, the anatomy goes:
    • 4) sepal 3) petals 2) stamen 1) carpel
    • gene A controls sepals/petals
    • gene B controls petals and stamen
    • gene C controls stamen and carpel
    • where gene A is present, C is inhibited and vice versa; if one of those is missing however, the OTHER takes its place
    • ·ABC genes are homologous to hox genes in that they’re organ identity genes and code for transcription factors
  17. floral patterns of mutants:
    • Mutant lacking gene A: has carpels, stamens, carpels (apetela2)
    • Mutant lacking gene B: sepals and carpels (pistilata)
    • Mutant lacking gene C: sepals, petals, sepals (agamous, no gametes)
  18. orientation of _________ microtubule band determines the plane of cell division
    • pre-prophase;
    • -a transverse microtubule band results in anti-clinal division
    • -a radial microtubule band results in peri-clinal division
  19. plane of cell division determines:
    change in organ shape; ALSO cell divisions in the same plane (transverse) produce a single file of cells (anti-clinal); cell divisions in three planes (radial/peri-clinal) give rise to a cube
  20. direction of cell expansion OBVIOUSLY affects cell shape:
    water uptake is the force by which a cell expands, however the orientation of cellulose microfibrils (located in cell wall) control the direction of expansion; the orientation of the microfibrils is controled by microtubles (the cytoskeleton) in the cytoplasm
  21. nitrogen: the most essential element for plant growth
    lateral root meristems are formed inresponse to the environmental cues, one being nitrogen; in low amounts it stimulates lateral root outgrowth; in high amounts, it represses LRG
  22. Ethanol
    when isolated from cell wall cellulose is an important energy source; additive to gasoline, improves its performance
  23. transport of water and nutrients occurs on 3 levels:
    • 1) environment to cells: (ex: uptake nutrients into root epidermal hair cells)
    • 2) cell-to-cell: short distance, at the levels of tissues and organs (ex. from leaf mesophyll cell into sieve tube of phloem)
    • 3) long distance: Xylem & Phloem (bulk flow) transport within the plant vascular system (xylem and phloem) at the level of the whole plant (ex. from roots to leaves)
  24. plant cells use energy (voltage) stored in the _________ potential to drive the transport of ______ into the cell
    membrane; cations
  25. the transport of K+ (potassium ions) into guard cells:
    lowers the water potential (because it increases the solute concentration), resulting in an influx of water into guard cells; thisinflux of water into guard cells causes increased turgor pressure (of the guard cells) OPENING them
  26. Water potential y (psi) is measured in MegaPascals and equals:
    water potential = pressure potential + solute potential; the water potential of a solution is always negative (compared to pure water); and the pressure potential is the physical pressure exerted by the cell wall onto a solution
  27. Image Upload 1
    • 1st = hypotonic (too few solutes); here a plant cell is turgid, animal cell lysed
    • 2nd = isotonic; plant cell is flaccid, animal cell is normal
    • 3rd = hypertonic (too MANY solutes, hyper, get it); plant cell plasmolyzes and animal cell shrivels
  28. transport routes at tissue level between cells (3):
    • transmembrane: through the selective plasma membrane
    • symplastic: through the continuum of cytosol through plasmodesmata
    • apoplastic: through the continuum of cell walls and extracellular space (NOT selective)
  29. genetically modified plants have the possibility to increase quality and quantity of food worldwide. Examples include:
    genetically modified “golden rice,” which has inserted genes to produce vitamin A in seeds; genetically modified papaya with a resistance to ring spot virus
  30. role of hormones in phototropism (the tendency for a plant to grow toward light):
    • 1) the light is percieved by the tip of the plant, because during experiments when the tip was covered by an opaque cap, the plant didn't exhibit phototropism (but DID when the tip cap was transparent, or part of the plant's body was covered)
    • 2) the hormone is mobile: shown by the fact that the plant was phototropic when the tip was separated from the body by a gelatin block, but not when separated bu mica
  31. auxin (IAA)
    causes cell elongation, especially on the DARK side of a plant, making it grow TOWARD the light; is a growth enhancing hormone; transportated long distance throught the PHLOEM (from shoot TO root tip)
  32. cytokinin
    responsible for cell division; growth enhancing hormone; made in actively growing tissues (ex: roots, embryos, fruits);
  33. gibberellin (GA)
    promotes seed germinatione; growth enhancing hormone
  34. brassinosteroid
    responsible for cell division and elongation in the stem, but inhibits ROOT growth; both positive and negative regulator; is a both a growth enhancing and inhibiting hormone; structurally and functionally similar to human sex hormones (testosterone)
  35. abscisic acid (ABA)
    promotes seed dormancy; represses growth of embryo; can be washed out with water so seed starts to grow; is a growth inhibiting hormone; increases 100 fold during seed maturation
  36. ethylene
    a gaseous hormone that promotes senescence and fruit ripening; is a growth inhibiting hormone; causes leaf abscission (they fall off); effects of ethylene can be INHIBITED by silver nitrate; the hormone is produced when a plant is wounded/trying to grow AROUND something: the greater it is in concentration the more curved/wide a plant stem will grow
  37. auxin stimulates ATPase/proton transport into cell wall (acidification):
    • auxin can act as a charged anion (IAA-) in the cytoplasm (pH 7); in the more acidic cell wall (pH 5.5) there is some uncharged auxin (IAAH); uncharged IAAH crosses the plasma membrane INTO the cell where it's deprotonated (turned into IAA-) and then can't exit EXCEPT with the help of specific auxin transporters (PIN)
    • RESULTS: stimulates proton pumps and LOWERS the pH in the cell wall; this acidification breaks down enzymes/polysaccharides/microfibrils; makes it more easily stretchable because the walls are looser (and the inside of the cell takes in water)
  38. thigmotropism
    directional growth in response to touch; occurs in vines/climbing plants; Mimosa's closing right when touched is an example of electrical impulse/action potential transmission; also seen in arabidopsis when exposed to certain decibles of talking heads: growth was stunted
  39. ratio of cytokinin to auxin is important in:
    specifying shoot vs. root cell differentiation!
  40. punched holes of tobacco leaf and treated with auxin, cytokinin or both:
    when treated with high auxin = lots of root growth; when treated with high cytokinin = shoot growth; when the sample was treated with equal hormone levels it doesn’t know which to be, so it stays a blob; what's weird is that they're made in opposite ends of the plant (auxin made in shoots, transported to roots through phloem, CK made in roots, transported to shoots via XYLEM ugh)
  41. a seed will germinate in response to:
    • light, GA (gibberellin), water/heavy rain
    • a seed will remain DORMANT in response to ABA (abscisic acid)
  42. ein vs. ctr mutants
    ein mutant FAILS to undergo the triple response in the presence of ethylene (aka it grows uninhibited); ctr mutant exhibits the triple response WITHOUT any ethylene
  43. action spectra shows that phototropism (bending toward light) is mediated by:
    blue light perception; the phototropic bending toward light is caused by cryptochrome (photoreceptor) sensitive to blue light
  44. photoreceptors
    proteins dimer (two proteins) linked covalently to chromophores that absorb types of light
  45. apadopsis Hy mutants are impaired in:
    red or blue light perception or signal transduction; in wild type/regular plants, both red and blue light inhibits hypocotyl elongation; hy (for hypocotyl) mutants either don't percieve the light (insensitive) or have issues signialing the presence of light so they GROW when exposed to light
  46. phytochrome
    photoreceptor that absorbs types of red light; made up of 2 domains: kinase (where light transcription factors phosporylate) and the chromophore binding domain (where the light is absorbed)
  47. phytochrome exists in two reversible states:
    Pr (red, inactive) and Pfr (far red, active); when phytochrome is active the responses range from seed germination, control of flowering, etc.
  48. in the morning there's an influx of ___ light, transforming phytochrome into its active state: ___
    during dusk there's an influx of ___ ___ light, transforming phytochrome into its INactive state: ___
    • red light --- transforms into Pfr (active state)
    • far red light --- transforms into Pr (inactive state)
  49. ___ light increased germination, ___ ___ light inhibited germination and the response depended on the last flash
    red increases, far red decreases germination; the response depended on teh LAST. FLASH!
  50. photoperiod
    the relative length of night/day; plants measure using phytochrome and circadian clock; is the environmental stimulus plants use MOST to detect the time of year
  51. photoperiodism
    physiological response to a photoperiod, like flowering time which involves measuring day/night length
  52. florigen (FT)
    flower promoting signal
  53. gravitropism; roots show _______ gravitropism while stems exhibit ________ gravitropism
    response to gravity that may be detected using statoliths; roots show POSITIVE gravitropism (they grow down, duh) while stems show NEGATIVE gravitropism (they grow up, against gravity)
  54. plants second line defense system is enhanced by its ability to:
    recognize certain pathogens and mount a systemic response; pathogen makes an Avr gene which acts as a ligand --- the plant can defend against it if it has an R-receptor; analogous to antigen:antibody recognition trigger of immune response in animals
  55. if a plant recognizes a pathogen it mounts a:
    hypersensitive response: lesions are made to kill the infected parts of the plant and the bacteria; during this process DYING plant cells release salicylic acid (hormone) to the rest of the plant which innitiates a signal transduction pathway; RESULT: SAR (systemic acquired resistance)! Yay now plant's resistant
  56. if you wanted you could go back to the evolution slides because you didn't finish those.
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