Final Exam

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kabrown
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17950
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Final Exam
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2010-05-05 15:54:03
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Plant Pathology
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Questions from the last three tests to study for the final exam
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  1. What is the difference between a symptom and a sign?
    • Symptom- the hosts reaction to a pathogen; Sign- Observing
    • the pathogen itself
  2. What are the three factors represented in the disease
    triangle? Why are they required?
    • HOST that is susceptible PATHOGEN that is capable of causing disease
    • ENVIRONMENT that is favorable for disease to develop….required for the disease
    • to develop…if any of the 3 are lacking: no disease occurs
  3. Provide characteristics that are commonly true for
    biotrophs.
    • Keep host alive,
    • host will remain green but may be stunted, have
    • narrow host ranges, cannot be cultured on media, attack healthy host tissue
    • at any stage, kill host cells slowly, penetrate
    • directly or via natural openings, includes all viruses most nematodes
    • parasitic plants and some fungi
  4. Provide characteristics that are commonly true for
    necrotrophs.
    • May kill host,
    • causes lots of necrosis, have wider host
    • ranges, can be cultured on media, attack
    • young weak or senescent tissues, kills host rapidly with toxins or enzymes,
    • penetrates through wounds or natural
    • openings, include most bacteria many fungi and oomycetes
  5. Name the 5 types of symptoms and some examples
    • Necrotic (dead
    • cells) – leaf spot, blotch, blight, scorch, canker, rot, and damping off. Secretion
    • of Liquids— bleeding, gummosis, and resinosis. Changes
    • in Coloration—mosaic, mottle, streak, stripe, yellowing (chlorosis). Changes
    • in Form—stunting, rugosity, leaf roll, galls, witches’ broom. Wilt—rot.
  6. What is an infection court?
    • The place on a plant that is susceptible to infection
    • (stoma, natural openings, wounds)
  7. What is colonization?
    • The time after infection that a pathogen reproduces
    • and multiplies
  8. What is the incubation period?
    • The time from penetration to when symptoms of infection
    • appeared.
  9. What is the secondary inoculum?
    • Inoculum produced by infections that took place
    • during the same growing season. The part of a pathogen that results in new
    • disease with the same season
  10. What is Koch’s postulate?
    • The name of the procedure used to prove that a specific
    • organism is the cause of a disease.
  11. What are the 4 disease management strategies?
    • AVOIDANCE—grow
    • the plant where or when the pathogen is not present or active. EXCLUSION—legal restrictions
    • (quarantines, pathogen free seed, or propagation parts). ERADICATION—removal of pathogens from infested soils and tools,
    • infected seed or propagation parts. PROTECTION—protect
    • plant from pathogen (spray fungicides or plant resistant cultivars)
  12. What are the sexual and asexual spores of
    Basidiomycetes, Ascomycetes, Zygomycetes, and Oomycetes?
    • Basidiomycetes:
    • sexual-basidiospores, asexual- usually not present. Ascomycetes: sexual- ascospores, asexual- conidiaspores. Zygomycetes: sexual-zygospores,
    • asexual- sporangiospores. Oomycetes:
    • sexual- oospores, asexual- zoospores.
  13. What fungal group do most plant pathogens belong to?
    Ascomycetes
  14. What is the difference between a heteroecous rust and
    an autoeceous rust? Provide an example
    of each.
    • ) Heteroecous—needs two unrelated host plants
    • (cedar-apple rust); Autoeceous—only needs one host (peanut rust)
  15. Cell walls of oomycete hyphae are primarily composed
    of what?
    Cellulose
  16. Cell walls of fungal hyphae are primarily composed of
    what?
    Chitin
  17. The ploidy level of oomycete in its dominant phase is
    what?
    Diploid
  18. The ploidy level of fungal hyphae in its dominant phase if
    it is a zygomycete or ascomycete is what?
    ) Haploid
  19. The ploidy level of fungal hyphae in its dominant phase if
    it is a basidiomycete is what?
    Dikaryotic
  20. What is one similarity between a chlamydospore and a
    condium?
    Both are asexual
  21. Most plant pathogens are..
    Facultative parasites
  22. Name 2 mollicutes. What are mollicutes?
    Phytoplasmas and Spiroplasmas. Mollicutes are bacteria that lack a cell wall.
  23. Are most plant pathogenic bacteria gram negative or gram positive?
    Gram negative
  24. The prescence of slime in a KOH test indicates what?
    gram negative bacteria
  25. Analysis of DNA sequence on 16S ribosomal gene is useful to..
    ID species
  26. How do the flollowing differ:
    Xanthomonas axonopodis pv. citri and Xanthomonas axonopodis pv. vesicatoria
    • different pathovars; indicates host differences
  27. How does a fungal leaf spot differ from a baterial leaf spot?
    Fungal- uasually round; Bacterial- follows veins, could be vertical or triangular
  28. Provide 2 signs that are unique to bacterial pathogens.
    bacterial streaming and oozing
  29. Characteristics of Basidiomycetes
    septate hyphae, clamp connections, basidium
  30. Characteristics of Ascomycetes
    septate hyphae, ascus
  31. Characteristics of Zygomycetes
    coenocytic hyphae, sporangia
  32. Characteristics of Oomycetes
    coenocytic hyphae, sporangia
  33. one way that facultative parasitic bacteria survive when they are not parasitic to a host
    as a saprophyte in the soil
  34. Difference between direct and indirect penetration
    Direct- enter host through an opening the pathogen created; Indirect- enter through natural opening or wound
  35. What type of penetration do facultative parasitic bacteria use?
    INDIRECT
  36. Name the host and disease of Xylella fastidiosa subsp: multiplex
    Disease- bacterial leaf scorch; Host- wodded plants (oak and elm)
  37. Host and disease of Septoria tritici
    Disease- leaf blotch of wheat; Host- wheat
  38. Host and disease of Blumeria graminous
    Disease- powdery mildew; Host- wheat
  39. Host and disease of Claviceps purpurea
    Disease- Ergot; Host- wheat
  40. Is septoria tritici monocyclic or polycyclic
    polycyclic
  41. What is the initial inoculum of Xylella fastidiosa? How is inoculum dispersed?
    The bacteria itself. Dispersed through insect vectors
  42. In Claviceps purpurea: what is initial inoculum? Secondary inoculum? How is secondary inoculum dispersed?
    Ascospores. Conidia. Conidia dispersed by wind
  43. Is Blumeria graminous necrotroph or biotroph?
    Biotroph
  44. What type of spore is produced in corn smut?
    Teliospores
  45. What is the function of clamp connections?
    To prolong the dikaryotic phase
  46. Which fungus is believed to be the largest organism on earth?
    Armillaria Root Rot
  47. Are plant parasitic nematodes obligate or facultative parasites
    obligate
  48. Migratory ectoparasite
    feeds on plant surface, only stylet enters plant, moves from cell to cell and sometimes plant to plant
  49. Sedentary endoparasite
    feed from inside plant tissue, does not move, stays in one feeding site and dies there
  50. What type of reproduction does bacteria use? By what process?
    Asexual reproduction. Binary fission
  51. What can be concluded about a nematode with a stylet
    It may be parasitic however not all parasites with stylets are parasitic
  52. Provide info for Trichodorus
    Stubby root nematode, migratory ectoparasite, affects root, unique symptom of stubby root
  53. Provide info for Heterodera
    Cyst nematode, sedentary endoparasit, affects root, unique symptom is cyst on root
  54. Provide info on Pratylenchus
    Lesion nematode, migratory endoparasite, affects underground plant part (root), unique symptoms are lesions on underground plant parts
  55. Provide info on Aphelenchoides
    Foliar nematode, migratory endoparasite, affects leaf, unique symptoms are lesions on leaf
  56. Provide info on Meloidogyne
    Root knot nematode, sedentary endoparasite, affects root, unique symptoms is the root knot (change in form)
  57. Common name for 2 nematodes that can transmit viruses
    Dagger and Needle nematodes
  58. In what stage do plant parasitic nematodes hatch
    J2
  59. What are the two nematodes that can only initiate infection at the J2 stage? What do they have in common?
    Root knot and cyst nematodes. Both are sedentary endoparasites so they stay at one feeding site inside plant tissue until they die
  60. Soybean cyst nematode has a *** host range. It establishes feeding sites called ***** by secreting **** from their *****.
    narrow, syncytia, polysacharrides and protein, stylets
  61. Soybean Cyst nematodes overwinter in ******* and it can be dispersed over long distances by *****..
    leathery cuticle of female's dead body, wind blown soils and birds (ingestion)
  62. What is one limitation of crop rotation
    It could be hard to trade out crops and cost more money
  63. One limitation of fumigant nematicide
    It can be harmful to the growth of plants and harmful to humans
  64. Are plant parasitic viruses obligate or facultative parasites
    obligate
  65. What is the function of a movement protein?
    Movement of virus (help with cell to cell movement through plasmodesmata)
  66. Function of replicase (RNA-dependent RNA polymerase)
    replicate virus within host
  67. Provide 2 specific change in color symptoms caused by viruses
    mosaic and mottle
  68. The only viral sign that can be observed with a compound light microscope
    inclusion bodies- crystalline clusters
  69. If a healthy lower leaf of a resistant plant in inoculated with a virus what type of symptom would you see and where would you see it?
    Hypertension response, on the lower leaf that was innoculated
  70. Persistent insect vector transmission
    virus located within salivary glands, not immediately transmissible, vector can transmit virus from hours to days
  71. Nonpersistent insect vector transmission
    virus located within stylet, immediately transmissible, vector can transmit virus for a few hours
  72. Persistent propagative insect vector transmission
    virus reproduces within vector (salivary glands), not immediately transmissible (latent period), can transmit virus for the entire life of the insect vector
  73. Example of vertical transmission
    transmission from mother to seed
  74. Viral genome can move from cell to cell through ***** and from *******through ******
    plasmodesmata, source to sink, phloem
  75. Full name of TMV
    Tobacco Mosaic Virus
  76. Full name of CMV
    Cucumber Mosaic Virus
  77. Full name of TSWV
    Tomato Spotted Wilt Virus
  78. What viruses are multiparticulate
    TSWV, CMV
  79. The virions of which virus are encapsulated by a membrane of host origin
    TSWV
  80. Common name of the insect vector of TSWV
    Thrips
  81. 2 viruses that have genes that code for proteins that interfere with RNA silencing by the host
    TSMV and CMV
  82. Hemiparasite
    Root- to get water and minerals from xylem, capable of photosynthesis
  83. Holoparasite
    All of plant--food, water, and minerals through phloem and xylem, not capable of photosynthesis
  84. Examples of holoparasite
    Dodder, Broomrape, and Dwarf Mistletoe
  85. Examples of hemiparasite
    leafy mistletoe, witchesweed
  86. What parasitic plant grows as a yellow vine
    Dodder
  87. What parasitic plants includes species in Phoradendron genus
    leafy mistletoe
  88. 1 crop that belongs to Solanaceae
    tomato
  89. Why is removing the leafy portion of leafy mistletoe not enough to eradicate the pathogen?
    Because the haustoria (which is taking plant nutrients) extends deeper into the plant
  90. Your neighbor has leafy mistletoe hanging on their front porch, you have a tree that is susceptible. What do you do?
    Ask the neighbor to take it down because birds are attracted to the fruit and can spread the disease to your tree by ingesting from the mistletoe and pooping on your tree. (avoidance)
  91. Sunscald is caused by
    excess sunlight
  92. The abiotic factor that causes the most damage to plants around the world is
    insufficient moisture (drought)
  93. Info about carbon
    macronutrient, enters plant through air (stomata)
  94. Info on Nitrogen
    Macronutrient, enters plant through roots (enters phloem)
  95. Info on Iron
    Micronutrient, enters plant through roots (enters phloem)
  96. Info on Copper
    Micronutrient, enters plant through roots (phloem)
  97. Info on Potassium
    Macronutrient, enters plant through roots (phloem)
  98. Info on Calcium
    Macronutrient, enters plant through roots (phloem)
  99. If an element is mobile through what tissue will it move and in what part of the plant would the symptoms first appear?
    phloem, in bottom leaves first
  100. Two nutrient elements that are mobile
    nitrogen, potassium
  101. Two nutrient elements that are immobile
    calcium, iron
  102. What are some clues that suggest a disease symptom is caused by an abiotic factor
    symptoms appear suddenly, symptoms are uniform throughout entire plant, there is a distinct line between symptoms of affected part of the plant and unaffected parts of plant
  103. What are saprophytic plant pathogens? explain
    soil invaders--they are less competitive than soil inhabitants and their populations drop quickly without a host but also recover quickly when host is introduced
  104. Where do epiphytes of the rhizosphere survive and what do they feed on?
    on top of root surface, feed on exudates on surface
  105. Phenological synchrony
    host and pathogen synchronize, pathogen produces inoculum when host is susceptible
  106. Chemotaxis
    used to direct movement of nematodes toward roots
  107. Fungistasis
    keep spores from germinating too soon
  108. A pathogen that produces lignase is capable of degrading ***. What plant would be a suitable host for a pathogen that produces this enzyme? why?
    wood, oak tree because lignase is complex and is best at wood decaying
  109. Are nonspecific toxins pathogenicity factors or virulence factors
    virulence factors
  110. What ype of toxin is the T toxin produced by Bipolaris maydis
    host-specific toxin
  111. Fuction of Gibberellins
    stimulates stem elongation
  112. Function of Cytokinins
    promotes cytokinesis
  113. Function of Auxin
    promotes mitosis and cell expansion
  114. Function of Ethylene
    promotes tissue maturity
  115. Function of Salicylic Acid
    activates genes that aid in defense
  116. What hormone imbalance causes a gall
    overproduction of auxins and cyokinins by host
  117. What hormone imbalance causes premature defolitiation
    ethylene production by pathogen
  118. What hormone imbalance causes witches broom
    multiple hormone imbalance in host
  119. What hormone imbalance causes Etiolation
    gibberellins produced by pathogen
  120. What hormone imbalance causes stunting
    down regulation of gibberellins in host
  121. Induced chemical Defense
    Induced defense mechanism that is biochemical (produced before symptoms occur
  122. Constitutive Chemical Defense. Example.
    Active defense mechanisms that are biochemical. secondary metabolites (already produced, not induced)
  123. Induced Structural Defense. Example
    Induced defense mechanisms that are structural (produced before symptoms occur). Changes in cell wall form
  124. Constitutive Structural Defense. Example.
    Active defense mechanisms that are structural (already present, not induced). Waxy cuticle
  125. What does SAR stand for
    Systemic Acquired Resistance
  126. What does ISR stand for
    Induced Systemic Resistance
  127. What is the gene for gene hypothesis. what type of resistance does it explain
    For every gene a plant has for resistance a pathogen has one for virulence and vise versa...it explains complete resistance
  128. AVR gene + R gene = ?
    Hypersensitivity Response
  129. AVR gene initiates disease on a host that does not have R gene what would occur?
    There would not be complete resistance so disease would occur
  130. What is the function of avr genes for pathogens on hosts that do not have R genes?
    Virulence or pathogenicity factors
  131. Function of avr genes for pathogens on hosts with R genes
    Signal (elicitor)
  132. An alternative name for complete resistance
    specific
  133. Alternative name for partial resistance
    non specific
  134. Complete resistance more durable with monocyclic or polycyclic pathogen
    monocyclic--there are less cycle happening therefore less of a chance to cause mutations
  135. Complete resistance more durable with airborne or soilborne pathogen
    soilborne-- because airborn pathogens spread more easily than soilborne leaving more chance for infection
  136. Complete resistance more durable with plant population with 2 compatible mating types or populations with only 1 mating type
    only 1 mating type because there is a smaller chance for genetic mutation
  137. What is one ecological concern about the use of GMO crops
    genes that were inserted into the GMO crops could spread to wild crops
  138. Cryphonectria parasitica
    fungus, disease- chestnut blight, host- chestnut tree
  139. Magnaporthe oryzae
    Ascomycete, disease- rice blast, host- rice
  140. Hemileia vastatrix
    Fungus, disease-coffee rust, host- coffee
  141. Erwinia Amylovera
    Bacteria, disease- fire blight of apple and pear, host- apple and pear
  142. Plasmopara viticola
    Oomycete, disease-downy mildew of grape, host- grape
  143. Phytophthora infestans
    Oomycete, disease- late blight of potato, host- potato
  144. Common name of a disease that causes stem canker
    sudden oak death
  145. Pathogens that cause stem cankers infect wi=hich tissues of stem
    phloem
  146. What is Antone DeBary famous for?
    recognizing there are plant pathogens rather than spontaneous disease
  147. What is Pierre Marie Alexis Millardet famous for?
    using fungicides on downy mildew of grape
  148. What is the main difference between a blotch and a blight
    Blotch- large location of dead cells; Blight- covers more area of dead cells (can appear burned)
  149. What disease is a concern because of the production of mycotoxins
    Fusarium head blight
  150. What does AUDPC stand for
    Area Under Disease Progress Curve
  151. Name 2 ways a pathogen can travel long distances (in citrus canker)
    tools that havent been cleaned, vectors (such as humans moving them)
  152. Reason that recent eradication of citrus canker was unsuccessful
    The hurricanes blew the disease around and spread it even further

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