Spring.wmf (18300 bytes) Plant Physiology (Biology 327)  - Dr. Stephen G. Saupe;  College of St. Benedict/ St. John's University;  Biology Department; Collegeville, MN  56321; (320) 363 - 2782; (320) 363 - 3202, fax;    ssaupe@csbsju.edu

  Test Yourself:  Plant Growth Substances

For each of the following, indicate the appropriate hormone (auxin, gibberellin, ABA, cytokinin, ethylene).  There may be more than one correct answer for some questions.

  amounts that stimulate shoot growth inhibits roots
  delays senescence
  derived from a catabolic pathway


  fattens cells

first detected in foolish seedling disease

  first observed because of aberrant growth of rice
  forms bound complexes with glucose or other compounds
  found in commercial rooting preparations
  benzyladenine has a similar activity
  basipetal transport
  associated with crown gall formation
  active in phototropism and gravitropism
  first discovered by Frits Went in bending of oat coleoptiles
  important in embryogenesis
  involved in leaf abscission
  planar ring with 0.5 nm charge separation polar transport

promotes fruit ripening

  promotes senescence

obtained from coconut milk


more than 100 types known


maintains dormancy


involved in witches broom formation


involved in thigmomorphogenesis


related to the climacteric

  responsible for epinasty

silver ions inhibit actions


some think they may be made by bacteria rather  than plants


split pea curvature test


stimulates conversion of etioplasts into chloroplasts

  stimulates dicot cotyledon expansion
  stimulates ethylene synthesis
  used in malting industry

stimulate root initiation

  associated with the anticodon region of tRNA
  derived from Greek word meaning "to grow"
  2,4-D is a synthetic version
  tri-iodobenzoic acid (TIBA) inhibits transport of this hormone
  results in short, fat and stupid seedlings
  helps provide embryo with desiccation tolerance



  controls morphogenesis of plant tissue cultures
  derived from carotenes (tetraterpenes)
  dioxin is a byproduct of the manufacture of these hormone analogs
  apples are a rich source of this hormone
  closes stomata
  chemically similar to nucleotide in DNA
  causes loosening of the cell wall
  carbon dioxide inhibits many actions
  occurs as free base, nucleoside, nucleotide
  breaks dormancy in seeds and buds
  biosynthesized from tryptophan
  coconut milk is a rich source
  coded by two genes on the Ti plasmid
  indole ring

involved in apical dominance


promotes flowering of pineapples

  prevents vivipary
  promotes stem elongation in intact plants
  parthenocarpic fruit development

often antagonistic to effects of ABA


napthalene acetic acid has similar activity


molecule with 4 or 5 rings


methionine is the amino acid precursor

  HCN produced during biosynthesis

reverses dwarfing in some plants


reverses juvenility in ivy


stimulates a membrane-bound proton pump


stimulates amylase production in cereal grains

  stimulates cell elongation
  stimulates seed germination
  synthesis is stimulated by wounding

triple response


stimulates coleoptile/shoot elongation but inhibits root growth

  used to increase size and spacing in grapes
  affects sex expression in plants
  about 40 different structures are known

AMO1618 inhibits synthesis

  one bad apple spoils the whole bunch
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Last updated:  01/07/2009     � Copyright  by SG Saupe