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EXAM 3- General Mycology 427/527      

                                                   

 

(FOR 2012 Class: Remember that this exam will cover from the Zygomycota through the Basidiomycota, including the mycotoxin lecture by Dr. Cotty.)

Multiple Choice:

Circle all the correct answers.  There may be more than one correct answer.  (0.5 points for each correct answer)

 

1.            The general life cycles of the Zygomycota and Ascomycota share the following features:

 

                  a.  their hyphae is haploid

                  b.  their hyphae is diploid

                  c.  the diploid stage is limited to a single cell that does not undergo mitosis division

                  d.  plasmogamy may be by gametangial copulation (fusion)

                  e.  hyphal anastomosis

 

2.            The Zygomycota (Z) are thought to be more closely related to the Chytridiomycota (C) than to the Ascomycota and Basidiomycota.  This may be because

 

                  a.  they (Z) and (C) both produce sporangiospores

                  b.  they (Z) and (C) contain cellulose as the fibrous component of their cell wall

                  c.  like the Chytridiomycota, those that have hyphae are coenocytic

                  d.  like the Chytridiomycota they produce motile asexual spores

                  e.  the Ascomycota and Basidiomycota rely primarily on aerial spore dispersal, which the Zygomycota do not use

 

3.            The Entomophthorales differ from the other orders of the Zygomycota because

 

                  a.  their sporangium is forcibly discharged with the sporangiospores inside

                  b.  some members of the order are human pathogens

                  c. they have septate hyphae

                  d.  they are obligately associated symbionts with many plant species

                  e. they reproduce asexually by conidia

 

4.             Plasmogamy in the Ascomycota may occur by

 

                  a.  planogametic copulation

                  b.  fusion of two cells

                  c.  nuclear fusion in the ascus mother cell

                  d.  contact between a spermatium and an ascogonium

 

5.            An ascocarp is

 

                  a. a sac-like structure that contains ascospores

                  b.  composed of dikaryotic mycelium

                  c. composed of haploid mycelium

                  d. a sexual fruiting structure of the Ascomycota

6.            The order Taphrinales, of the Hemiascomycetes, differ from the other order, the Endomycetales because the Taphrinales

 

                  a.  usually produce 1000 ascospores per ascus

                  b.  are plant parasites

                  c.  have a dikaryotic hyphal stage

                  d.  have naked asci

 

7.            Asexual growth of Saccharomyces cerevisiae can involve

                  a.  budding

                  b.  hyphal growth

                  c.  haploid cells

                  d.  diploid cells

                  e.  mitosis

 

8.            The size of the form-Phylum Deuteromycota is decreasing because

                 

                  a. some of these fungal species are evolving sexual stages

                  b. as sexual stages are being associated with their anamorph stages, species are being reclassified into either the Ascomycota or Basidiomycota

                  c.  their habitat is decreasing forcing many into extinction

                  d.  molecular phylogenetics are allowing species to be reclassified into the Ascomycota or Basidiomycota based on DNA sequence similarities

 

9.            The Form-Class Coelomycetes of the Deuteromycota

 

                  a.  do not produce conidia and are known as the Mycelia sterilia

                  b.  produce sporangiospores inside an acervulus

                  c.  produce conidia in fruiting bodies

                  d.  are those mycelial fungi that do not make asexual fruiting bodies

                  e.  is sub-divided into form-orders based on whether species make a  pycnidium or an acervulus

 

10.        Saccardo designed a system around 1900 to classify many species of the Deuteromycota based on

 

                  a.  mode of conidium development

                  b.  spore shape

                  c.  the number and arrangement of cells in a conidium

                  d.  conidial pigmentation

                  e.  presence or absence of a yeast-like stage

 

11.          The Hughes-Barron system that was considered an improved method to categorize many of the Deuteromycota species is based on

                  a.  mode of conidium development

                  b.  spore shape

                  c.  the number and arrangement of cells in a conidium

                  d.  conidial pigmentation

                  e.  presence or absence of an ascocarp

12.        The genus Aspergillus

                 

                  a. is named because its conidiophore looks like a holy water sprinkler

                  b. has a species that is used for the production of citric acid which is in many foods we eat

                  c. is responsible for flavoring and ripening roquefort and camembert cheese

                  d. produces the deadly toxin, aflatoxin

 

13.          The Homobasidiomycetes

                 

                  a.  are those basidomycetes whose basidiospores are self-fertile

                  b.  is an order of the Basidiomycota that includes the mushrooms

                  c.  are those basidiomycetes which have single-celled basidia

                  d.  includes the gilled mushrooms, the puffballs, and the stinkhorns

                  e.  those basidiomycetes that lack a hymenium and produce their basidia in a gleba

 

14.        Clamp connections are

                 

                  a.  hyphal bridges formed between adjacent cells during cell division in homokaryons of the Basidiomycota

                  b.  formed during mitosis in most Basidiomycota dikaryons

                  c.  not found in the rusts (Uredinales)

                  d.  structures that allow the passage of the contents of the male gametangium into the female gametangium

                  e.  a hyphal structure that allows maintenance of the dikaryon

 

15.        The number of ascospores per ascus may vary between 1 and 1000 thousand

                 

                  a.  because there may be single or multiple rounds of meiosis per ascus

                  b.  the statement in the question is false

                  c.  depending on how many rounds of mitosis occur after meiosis

                  d.  but is always the same within a class of the Ascomycota

 

16.        The Uredinales (rusts) and Ustilaginales (smuts) differ from the other Basidiomycota by

                  a.  the formation of a thick-walled teliospore in which karyogamy occurs

                  b.  their lack of ballistospores

                  c.  the lack of a basidiocarp

                  d.  all having complex life cycles often with two hosts and five spore stages

                  e.  having meiosis take place in a metabasidium which forms on the teliospore

 

17.        The Uredinales differ from the Ustilaginales because they

                  a.  have a simpler life cycle involving one host instead of often two, for the Ustilaginales

                  b.  lack clamp connections in their life cycle

                  c.  produce teliospores within a host organ, like a seed, often replacing the contents of that organ

                  d.  undergo plasmogamy in a spermogonium

                  e.  are obligate plant pathogens for their whole life cycle

18.          The Jelly fungi

 

                  a.  are those Hemiascomycetes, which grow on plant exudates with a high sugar content (such as jam or jelly)

                  b.  are Heterobasidiomycetes which are gelatinous in appearance when wet.

                  c.  are capable of dehydrating and rehydrating as environmental conditions change

                  d.  is the common name for one order, the Phallales, in the class Homobasidiomycetes because of their gelatinous gleba

 

19.         An ascus mother cell and a basidium are similar because

 

                  a.  meiosis occurs in these cells and results in the production of four spores

                  b.  in many species, they are the site of karyogamy

                  c.  in many species they are the only diploid stage of the life cycle

                  d.  they are both formed at the top of a crozier

 

20.          A Uredospores is

 

                  a.  haploid.  Fusion of two uredospores of different mating types produces the dikaryon stage in rusts.

                  b.  dikaryotic

                  c.  reddish colored and responsible for the common name of the rust fungi

                  d.  able to re-infect their host and produce more uredospores

                  e.  a thick-walled resting spore of the Uredinales that is the site of karyogamy

 

 

True/False write true or false to the left of each answer  (1 point each)

 

1.  More than one ascus can develop from a single ascogenous hypha.

 

2.  The Powdery mildews got their common name because of the appearance of their conidial chains on plant leaf surfaces.

 

3.  The Deuteromycota are called a ÒformÓ-phylum because it is ÒformedÓ from members of the Ascomycota and Basidiomycota.

 

4.  Genetic recombination does not occur in the Deuteromycota

 

5.  Sacharomyces ludwiggii is said to have a short haploid phase because plasmogamy and karyogamy takes place between ascospores in the ascus

 

6.  A sporangiolum is a sporangium with less than 30 sporangiospores

 

7.  Gasteromycetes are Basidiomycota that lack a hymenium and produce basidiospores that are not forcibly discharged

 

8.  The dikaryon in the Basidiomycota is formed just before development of the basidiocarp

Short Answers:

 

1.  The Ascomycota and Basidiomycota are sometimes grouped as the dikaryomycetes because they both have a dikaryon phase. 

                  a.  For which phylum is the dikaryon free-living and for which is it not?  Explain what this means.  Also, how long may the dikaryon in this phylum exist? (3 points)

 

 

 

 

 

 

 

 

 

 

                  c.  For the phylum where the dikaryon is not free-living, what is its source of nutrients for the growth of the dikaryotic hyphae?  (1 point)

 

 

 

 

 

                  d.  Do the dikaryotic nuclei in Òc.Ó undergo mitosis? Explain (1 point)

 

 

 

 

 

 

2.            a.  Saccharomyces cerevisiae  is unusual among the Ascomycota in having no dikaryotic stage.  What specific aspect of its life cycle causes it to lack a dikaryotic stage? (2 points)

 

 

 

 

 

 

 

 

                  b.  What is the nuclear ploidy (haploid, diploid) of the asexual, budding phase of the S.cerevisiae life cycle?  Explain.  (2 points)

 

 

 

 

 

                  c.  Why is S. cerevisiae considered to be one of the most important fungi in terms of daily human life? (1 point)

 

 

 

 

 

 

3.            a What are the names of the ascocarps of the following classes of the Ascomycota?  Describe these structures (you may use drawings to assist your description). (5 points)

 

Hemiascomycetes

Pyrenomycetes

Plectomycetes

Loculoascomycetes

Laboulobenomycetes

 

 

 

 

 

                  b.  What is the nuclear ploidy of the ascocarp? (1 point)

 

 

 

 

                  c.  What is a bitunicate ascus and how does it differ from a unitunicate ascus?  Which class(es) have bitunicate asci? (2 points)

 

 

                 

                  d.  (Extra credit) Support the statement: Ascospore formation is more similar to sporangiospore formation than to conidiation? (2 points)

 

 

 

 

 

 

4.            a.  What are the distinguishing features of the conidiophores of the genera Aspergillus and Penicillium? Draw the conidiophores and label the phialides and conidia. ( 3 points)

 

 

 

 

 

 

4.             b. Do these two species use a holoblastic or enteroblastic mode of conidiation? Explain your answer (2 points)

 

 

 

 

 

 

5.            Draw a mushroom and label the stipe, cap, volva, annulus, and gills.  (3 points)

 

 

 

 

 

 

 

 

 

 

                  a.  What is the nuclear ploidy of each these structures? (2 point)

 

 

 

                  b. What is the hymenium (define)? and where is it in the structure?  (2 points)

 

 

 

 

 

                  c.  Where is the basidiocarp?  (1 point)

 

 

 

 

 

                  d.  Some mushrooms have scales on the pileus, a volva and an annulus.  From where did these structures each originate?  Explain.  (2 points)

 

 

 

 

 

 

(Extra Credit)

                  e.  What order is this mushroom from?  ( 1 point)

 

 

 

 

6.  A pycnidium and a perithecium superficially look similar.  You discover such a structure in the field.

                  a.  What features can you observe microscopically to determine which of these two structures you have found? (2 points)

 

 

 

 

 

                  b.  Can a single fungal species produce both pycnidia and perithecia. Explain your answer (2 points)

 

 

 

 

 

 

7.            The rust fungus Puccinia graminis is said to be macrocyclic and heteroecious.  a.  What features of its lifecycle do these terms refer to?  (3 points)

 

 

 

 

 

 

 

 

 

                  b.  Extra Credit:  Match the spore type to the description for P. graminis.  Write the nuclear ploidy for each spore type (n, n+n, or 2n) to the LEFT of the spore type.  (5 points) 

 

 

                  Basidiospore                                    formed on barberry, but infects wheat

 

 

                  Spermatium                                       overwintering spore

 

 

                  Aeciospore                                        male gametangium formed on barberry

 

 

                  Uredospore                                       causes repeated cycles of infection during the summer

 

 

                  Teliospore                                          formed following germination of the metabasidium

 

 

 

8.  That dreaded life cycle

 

a.             Label the following structures

                  i.  sporangium

                  ii.  stolon

                  iii.  rhizoids

                  iv.  suspensor cells

                  v.  zygospore

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b.             What is the nuclear ploidy of each

                  of the above structures? 

 

c.             How do the gametangia differ from each other

                  in this organism?  Where are they?

 

d.            Indicate on the figure where karyogamy takes place. 

                  Indicate where meiosis takes place.

 

e.             From this life cycle can you tell whether this organism is homothallic or heterothallic?  Support your answer.

 

 

 

Definitions:  (be concise; 1.5 points per definition)

 

crozier-

 

 

 

ascogonium-

 

 

 

trichogyne-

 

 

 

acervulus-

 

 

 

merosporangium-

 

 

 

Gasteromycetes -

 

 

 

MORE EXTRA CREDIT: 

 

What are the VAM fungi, what features of their life cycle give them their name (VAM) and how do they play an important role as a symbiont in nature?  (3 points)

 

 

 

 

 

 

 

 

What is that topic that you studied all night for, but I didnÕt put on the exam?  Write your question and answer for a sliding (1-5) scale.