PLANT REPRODUCTION QUESTION 1987:			L. PETERSON/AP BIOLOGY

	Describe the effects of plant hormones on plant growth and development.
	Design an experiment to demonstrate the effect of one of these plant 
	hormones on plant growth and development.

  
  STANDARDS:
  PART I. EFFECTS:                 Max. = 7 points
  __  For identifying a plant hormone
  __  For correctly defining a plant hormone
  For correctly describing the effects of a plant hormone (most frequently mentioned hormones and
  effects given below, but see addendum for a more complete master list):
  AUXINS
  __  Promote cellular elongation
  __  Promote softening of cell walls
  __  Involved in phototropism
  __  Involved in geotropism
  __  Involved in apical dominance
  GIBERELLINS
  __  Stimulate cell elongation
  __  Produce bolting in biennials
  __  Stimulate production of starch digestion enzymes in some seeds
  __  Reverse effects of genetic dwarfism
  CYTOKINETINS
  __  Promote growth in size of leaf cells
  __  Stimulate cell division
  __  Release buds from apical dominance
  ETHYLENE
  __  Promotes ripening of fruit
  ABSCISIC ACID
  __  Promotes stomatal closure
  __  Promotes resistence to water stress
  __  Promotes seed and bud dormancy
  __  formerly thought to promote abscission
  FLORIGEN
  __  May induce flowering
  Extra points, up to two, awarded for each association of a hormone with
  a correct, specific effect.
  In order for two points to be awarded, two different hormones must 
  be associated with their specific effects.
  PART II.  EXPERIMENTAL DESIGN         Max. = 7 points
  Appropriate understanding or indication of:
  __  Basing design on past observations or the literature
  __  Problem, statement, or question posed
  __  Hypothesis
  __  Use of adequate sample size or replicates
  __  Maintaining uniform conditions
  __  Control or understanding of the concept of control
  __  Treatment of experimental group
  __  Taking of data
  __  Evidence supports or refutes the hypothesis
  One extra point awarded for a particularly innovative experimental design and another for
  especially well organized and detailed description of the experiment.  
                                   Max. = 2 points
  
  
  
  
  
     ADDENDUM TO STANDARDS / MASTER LIST OF PLANT HORMONAL EFFECTS:
  AUXINS                           GIBBERELLINS
  
  promote cellular elongation.                    stimulate cell elongation in stem.
  promote phototropism in stems.             promote bolting and flowering in promote
  softening of cell walls.                   biennials.
  promote growth of branch or adventitious roots.      promote production of starch. promote
  renewed cell division in cambium.               digesting enzymes in grass seeds.
  promote differentiation of vascular tissue.          promote pollen germination.
  promote joining of vascular tissue of leaves         increase size of grapes and loosen     
    with that of stems.                        clusters.
  affect transcription of at least ten genes           break seed and bud dormancy.
   involved with growth.                     stimulate leaf growth in monocots.
  inhibit growth of main roots.                   inhibit root formation.
  inhibit production of abscission layer.              stimulate development of "male" 
   act as a herbicide for dicots.                             flower parts.
  exert apical dominance by inhibition of cell         stimulate auxin production.
   elongation.                          stimulate cell division at the stem
  artificially promotes parthenocarpy.              apex.                                                     may stimulate the production of 
                                     auxins.
                                   stimulate fruit-set in some species.
                                   stimulate vascular cambium to 
                                     produce secondary phloem.
                                   stimulate protein synthesis.
  CYTOKININS                            ABSCISIC ACID (ABA)
  promote growth in size of leaf cells.           promote stomatal closure.
  stimulate cell division.                        promote seed and bud dormancy.
  promote conversion of immature plastids         promote resistance to water stress.
   to chloroplasts.                     counters effects of auxin.
  inhibit senescence of leaves.                   induces apical meristem to stop 
  help break dormancy in some seeds.                mitosis and cytokinesis.
  enhance flowering in some plants.               induces leaf primordia to form 
  promote fruit development in some species.      protective bud scales.
  release lateral buds from apical dominance.          keeps twigs dormant until leaching 
                                     occurs.
                                   involved in root geotropism by 
                                     inhibiting elongation of cells on 
                                     lower side.
  ETHYLENE                              FLORIGEN   (hypothetical)
  promotes ripening of fruit.                may induce flowering.
  promotes radial growth in stems and roots.
  contributes to leaf drop.
  produces horizontal growth of stems.
  affects sex expression in some monoecious species.
  promotes wound healing.