Plant Structure and Function

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Plant Structure and Function
2013-09-24 20:00:59
Biology GRE

Biology GRE
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  1. Photoautotrophs
    Make own energy from light
  2. Bryophytes
    • First land pants
    • Ex: moss
    • Live close to water
    • Non Vascular
  3. Two Adaptations for land
    • Protective waxy cuticle to prevent dessication
    • Flagellated sperm that can swim in droplets of water to female
    • Stomata
  4. Alternation of Generations
    All plants alternate between haploid and dipliod
  5. Tracheophytes
    Have vascular tissue (xylem ad pholem)
  6. Gybosperms
    • Naked seeds
    • Vascular tissue
    • Not true fruits (do not have endosperm)
  7. Angiosperms
    • Flowering plants
    • Double fertilization to create endosperm and nourish plant enbryo
  8. Monocots
    • One Cotyledon (Seed leaf)
    • Narrow leaf shape
    • Leaf veins are parallel
    • Vascular bundels in stems are throughout/random
    • Fibrous roots
    • ex: grasses
  9. Dicots
    • Two Cotyledon (seed leaf)
    • Broad leaf shape
    • Leaf veins are branched
    • Vascular bundles in stems are around edges
    • Taproot system
  10. Leaves
    Provide most photosynthesis to plant
  11. Roots
    Support to soil, provide minerals and water
  12. Branches
    hold Leaves to light and convery nutrients and water to leaves and roots
  13. Root Hairs
    • Increase SA of roots to absorb water and nutrients
    • Symbiotic fungi can also help uptake of water and nutrients
  14. Legumes
    N2 fixing Rhizobium form symbiosis with root nodules
  15. Stomata
    • Openings that allow diffusion of CO2, O2, and water vapor
    • Size is controlled by guard cells
  16. Palissade layer and Spongy Layer
    • Pal- Densely pack photosynthetic layer 
    • Spongy- contains chloroplast with air spaces around cells, air spaces increase gas exchange
  17. Guard Cells
    • Control size of stomata
    • Open by day to allow CO2 exchange for photosynthesis
    • Closed by night to limit transpiration
    • More water in plant, guard cells swell and open allowing transpiration
    • Less water in plant, guard cells shrink and clam shut
    • Absorb water in response to K+ ions entering cells, sunlight causes K+ channels to open, triggered by light receptors
  18. Transpiration
    Evaporation of water from leaves that draws water up through plant
  19. Turgor Pressure
    Pressure water exerts on cells
  20. Meritstems
    Self renewing population of cell that divide and cause plant to grow in height and width
  21. Aplical Meristems
    Exist at tips of roots and stems
  22. Lateral Mertistems
    • Also called Cambium
    • Are in stem between xylem and phloem
    • Increase trunk size
  23. Primary Growth
    At apical meristems, upwards
  24. Secondary Growth
    Outward at lateral meristems
  25. Auxins
    • Plant hormone associated with growth
    • Responsible for phototropism, geotrophism
    • Terminal bud auxins travel down plant and prevent the formation of lateral buds that would be shaded by the top buds
    • Stimulate production of new xylem by cambium
  26. Negative geotropism
    • Usually in stems
    • Gravity increases concentration of auxin on lower side of horizontally turned plant (stem) 
    • Lower side being to grow faster due to auxins and plant stems again is vertical and growing upwards
  27. Positive Geotropim
    • Usually in roots
    • Horizontally turned root  have a higher concentration of auxins in bottom
    • Here they prevent growth
    • Top of root beings to grow faster forcing horizontal section down into ground
  28. Gibberellins
    • Plant hormone that stimulates stem elongation, especially on plants that don't grow especially tall 
    • Inhibits formation of new roots
    • Stimulates production of new phloem cells by cambium
    • Terminate dormancy of seeds
  29. Cytokinins
    • Promote cell division
    • Ratio of cytokinins to auxins is important in differentiation of buds and roots
    • More auxins, more roots
    • More Cytokinins, more buds
  30. Ethylene
    • Stimulates the ripening of fruit and loss of leaves during seasonal changes
    • Ethylene gas is used in the food industry to ripen unripe fruit for market
    • Ethylene inhibitors are important in winter so that plants do not produce fruit and waste energy on something that will die
  31. Symplast
    Cytoplasmic compartment made of continuous plasmodesmatea
  32. Tonoplast
    Membrane on central vacuole
  33. Xylem
    • Vascular tissue that contains column of water from roots to leaves
    • Leaves regulate transpiration, and water mores up vis root pressure and cohesion of water
  34. Root Pressure
    Pushes water up from roots, works best in short plants and humid environments where lots of water pools in the ground
  35. Dew
    • At day transpiration evidence (water on leaves) evaporated
    • at night creates dew
  36. Cohesion
    • Water molecules tend to stick together because of high polarity 
    • Transpiration happens because lower concentration of water in the air, pulls water up and out of plant
  37. Phloem
    • Vascular tissue that contains sugars
    • Much thinner walled then xylem
    • Outside edge of stems
    • Starts in leaves, where photosynthesis produces glucose, and moves down plant due to water potential
    • Creates osmotic potential that pulls more water into pholem and forces sap down phloem
  38. Macronutrients
  39. Micronutrients
    FE, MG, Cl, Cu, Mn, ZN
  40. Cation Exchange
    H+ ions are able to knock cations free of soil particles so they an be absorbed by root hairs
  41. Nitrogen
    • Nitrogen cannot be used with out nitrogen fixing bacteria 
    • Needed for DNA
    • Plants can use NH4, NO3
    • Most plants use nitrate preferentially over ammonium (NH4)
  42. Nitrogen cycle
  43. Tap root
    Primary root