Exam 2.1: Textbook

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  1. a.      Oomycetes and slime molds are __organisms once regarded as __
    • heterotrophic 
    • fungi
  2. Oomycetes
    - how many
    - cell wall
    - body types
    •                                                               i.      700 species
    •                                                             ii.      Cell walls: cellulose or cellulose-like polymers
    •                                                           iii.      Body Types:
    • 1.      unicellular to highly branched
    • 2.      coenocytic
    • 3.      filamentous forms that resemble the hyphae of fungi
  3. Oomycetes
    - reproduction
    • 1.      Asexually : by means of motile zoospores, which have two flagella (one ornamented with hairs and one smooth)
    • 2.      Sexually: oogamous (female egg is large and nonmotile and male is smaller and flagellate)
    • a.      One to many eggs are produced in the oogonium and an antheridium contains male nuclei
    • b.      Fertilization results from formation of a thick-walled zygote called the oospore
    •                                                                                                                                       i.      The oospore is the resting stage that can tolerate stressful conditions until they improveà germination
  4.                                                               i.      Aquatic Oomycetes
    1.      Water molds are abundant in __and easy to isolate from it
    2.      Most are __

    3.      A few are __, including species that cause disease of fish and fish eggs
    • freshwater 
    • saprotrophic, living on remains of dead plants and animals
    • parasitic
  5. Aquatic oomycetes cont. 

    1.      Some, like Saprolegnia, can undergo __
    a.      Homothallic: __
    2.      Others are heterothallic—__
    • sexual reproduction
    • male and female sex organs borne on the sane individual
    • male and female sex organs are on different individuals or if on one individual, that individual can’t fertilize itself
  6.                                                               i.      Terrestrial Oomycetes
    1.      Still form __ when liquid water is available
    2.      Some are very important economically
    a.      __: causes downey mildew in grapesà threatened wine industry
                                                                                                                                          i.      Solved with what?
    • motile zoospores
    • Plasmopara viticola
    •  a mixture of copper sulfate and lime: Bordeaux mixtur
  7. Phytophthora: generally does what?

    - cinnamomi?
    causes destruction of many cropss

                                                                                                                                          i.      Phytophthora cinnamomi killed millions of avocado trees; the zoospores are attracted to the plants they infect by chemicals exuded by the roots; also produces resistant spores
  8. Phytophthora ramorum ?

    •                                                                                                                                       i.      Phytophthora ramorum caused sudden oak syndrome by invading bark and girdles the tree
    •                                                                                                                                     ii.      Phytophthora infestans: caused late blight of potatoesà potato famine; led to emigration and death
    • 1.      Resistant strains have been commercially grown with some success
  9. a.      Pythium species are the most important causes of __, which kill young seedlings and attack crops
    damping-off diseases
  10. Saprolegnia: mycelium are __ and reproduction is mainly __.

    Asexual life cycle of Saprolegnia?
    • diploid
    • asexual 

    • a.      Biflagelltated zoospores are released from the zoosporangium and swim; they then enter encystà each encyst gives rise to secondary zoospores, which also encysts and germinate to form new mycelium
  11. Sexual life cycle of Saprolegnia
    • a.      Oogonia and antheridia are formed on same hyphaà meiosis occurs within these structures
    •                                                                                                                                       i.      In mating, the antheridia grow toward the oogonia and develop fertilization tubes, which penetrate the oogonia
    •                                                                                                                                     ii.      Male nuclei travel down the fertilization tubes to the female nuclei and fuse with themà oospore—(germination)à the oospore develops into a hypha, which eventually produces a zoosporangium
  12. What are oogonia?

    • Oogonia (enlarged cells in which a number of spherical eggs are produced)
    • antheridia (develop from tips of other filaments of same individual and produce numerous male nuclei)
  13. Plasmodial slime molds
    - how many and their relationship to other groups?
    - under appropriate conditions? 
    - cell walls?
    •                                                               i.      700 species; no direct relationship to the cellular slime molds, the fungi, or any other group
    •                                                             ii.      Under appropriate conditions, they exist as thin, streaming, multinucleate masses of protoplasm that creep along in amoeboid fashion
    •                                                           iii.      No cell walls: named mass of protoplasm is called plasmodium
    • 1.      As they travel, they engulf and digest bacteria, yeast cells, fungal spores, decaying plants and animal material
  14. PSM cont.

                                                                  i.      All plasmodial nuclei __
    1.      __are present, and __is similar to that of plants, although the __are very small
                                                                ii.      Typically, the moving plasmodium is __, with __
    • divide repeatedly and synchronously
    • Centrioles 
    • mitosis
    • chromosomes 
    • fan-shaped
    • folwing protoplasmic tubules that are thicker at the base of the fan and spread out, branch, and become thinner toward their outer ends
  15. PSM cont.

    1.      The tubules are composed of __ through which more __ flows rapidly
    a.      The foremost edge of the plasmodium consists of a __ separated from the substrate onl by a __ and a slime sheath
    • slightly solidified protoplasm
    • liquefied protoplasm
    • thin film of gel
    • plasma membrane
  16. PSM 
    - life cycle                                                              

    Plasmodial growth continues as long as __; what happens if there is none?
    1.      When the plasmodium stops moving, in many species, what does it do? It then does what? __
    a.      The protoplasm is cleaved into __, each with a __
    • adequate food and moisture are available
    • migrate away when there is none

    it divides into a large number of small mounds controlled by chemical effects

    produces sporangium whose protoplasm has many nuclei (increase in number by mitosis)

    • spores
    • diploid nucleus
  17. a.      Meiosis then occursà __
                                                                                                                                          i.      __disintegrate
    1.      In some members, __ are not produced, and the entire plasmodium may develop eitherinto a __, which retains the former shape of the plasmodium, oir into the __, in which the plasmodium forms a large mound that is essentially a single large sporangium
    • four haploid nuclei per spore
    • Three of four

    • discrete sporangia
    • plasmodiocarp
    • aethalium
  18.                                                               i.      When habitats dry out, the plasmodium forms the __
    1.      Important for survival of plasmodia slime cells
    encysted stage (sclerotium)
  19. 1.      Under favorable conditions, the spores __ and the __
    a.      Can remain __(feed by ingestion and multiply by mitosis or cell cleavage) or __(interconvertible)
                                                                                                                                          i.      If conditions are unfavorable, the amoeba may do what?
    split open

    protoplast slips out


    develop one to four smooth flagella 

    stop moving, become round, and secrete a thin wall to form a microcyst (very viable)
  20.                                                               i.      After a period of growth, plasmodia appear in the amoeba population
    1.      Formation is governed by several factors: __(4)__

                                                                  i.      One method of plasmodium formation is by __, which are genetically diferent from one another derived from different haploid spores

    1.      The gametes are some of the __ or __ that have a new role

    cell age, environment, density of amoebas, and cAMP

    fusion of gametes

    amoebas or flagellated cells
  21.                                                               i.      Life cycle of a typical miyxomycete
    1.      Sexual reproduction of plasmodial slime molds has three stages
    • a.      Plasmogamy: union of two protoplasts (can be amoebas or flagellated gametes derived from germinated spores)
    • b.      Karyogamy: fusion of the two nuclei, resulting in formation of diploid zygote and initiation of the diplophase of the life cycle
    • c.       Meiosis
  22. 1.      The plasmodium is __ and __ that can form __to survive and can form __, which, through meiosis, allows __ and __
    • multinucleate and free-flowing
    • sclerotium 
    • sporangia
    • restoration of the haploid condition and initiation of the haplophase of the life cycle
  23. Summary of the life cycle of myxomycetes
    a.      (Haplophase [n]) amoebas or flagellated gametesàPlasmogamyà karyogamyà 2n zygoteà plasmodiumà diplophase (2n) and formation of sporangiumà young sporangium—meiosisà mature sporangiumà sporesà mature sporeà germinating sporeàamoebas or flagellated gametes
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Exam 2.1: Textbook
2014-03-08 14:15:28
Plant Kingdom
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