FINAL EXAM                                                                                                           NAME:________________

General Mycology 427R/527R

 

 

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

 

1.            Fungi are different from plants because

 

                  a.  they lack organelles

                  b.  they are unable to fix CO2

                  c.  they rely on absorptive nutrition

                  d.  they are autotrophs

                 

2.             The majority of Fungal species

 

                  a.  require external water in order to digest their food

                  b.  reproduce by production of embryos

                  c.  get their nourishment from live organisms

                  d.  rely on dead matter for nourishment

                  e.  have likely not yet been identified

                 

3.             Hyphae are

 

                  a.  the filamentous growth structures of many fungi

                  b.  divided by septa in the Ascomycota and Basidiomycota

                  c.  divided by septa in the Oomycota

                  d.  surrounded by a cell wall

                  e.  absent in the slime molds

 

4.             A fungal species is named

                 

                  a.  using both the genus name and the species epithet

                b.  using the species epithet alone

                  c.  by its teleomorph name if it has both an anamorph and teleomorph

                  d.  by its anamorph name if it has both an anamorph and teleomorph

                  e.  many times due to revisions in identification, and their having both sexual and asexual structures (which is why Mycology is so darn confusing)

 

5.             Neurospora crassa was used by Beadle and Tatum

 

                  a.  to produce citric acid and thus break the Italian lemon monopoly

                  b.  because it was easy to produce both asexual and sexual spores for experiments

                  c.  to identify mutants that were unable to synthesize single nutritional compounds

                  d.  to develop the one gene-one enzyme hypothesis

                  e.  because it was able to be grown on a minimal medium unlike Drosophila

 

6.             Fungi are considered good models for genetic analyses because

 

                  a.  similar to humans, their cells are predominantly diploid

                  b.  it is easy to isolate and analyze mutant strains

                  c.  several disease-related genes in humans have homologs in fungi

d.      fungal genomes are much smaller than humans making them easier to work with

 

7.             Saccharomyces cerevisiae is so important to humans because it

                 

                  a. is responsible for most citric acid production

                  b.  can be used as a model to understand many human diseases

                  c.  uses sugars to produce CO2 during bread making

                  d.  is responsible for almost all of the alcohol production worldwide

 

8.             Secondary metabolites produced by fungi

 

                  a.  are often produced after the main growth phase is over

                  b.  are compounds that are conserved structurally in most fungal species

                  c.  may be isolated for industrial use such as antibiotics

                  d.  may be toxic to humans

                  e.  include amino acids and chitin

 

9.             Production of steroids

 

                  a.  can be accomplished by some fungi that have complete steroid biosynthetic pathways

                  b.  involves enzymes of fungi to modify some of the intermediates

c.       may involve more than one phylum of fungi

d.      may involve fungi and bacteria for different steps in the same pathway

e.      often begins with the extraction of the precursor progesterone from fungi

 

10.        In Medical Mycology, drug selectivity describes

 

a.      the process by which a doctor selects which medication to use to treat a fungal infection

b.      a drug whose target is found in the pathogen and not in the host

                  c.  a drug which targets a single cellular process like protein synthesis

d.  how effective a drug is at killing a fungus

 

11.          Mycotoxins    

 

                  a.  are defined as Òfungal substances that cause a pathological condition in humansÓ

                  b.  may affect plants as well as animals

                  c.  are compounds produced by a host organism to kill a fungal pathogen

                  d.  are often ingested accidentally when food is contaminated by fungi

                  e.  are usually compounds that are essential for normal fungal growth 

 

12.          Aflatoxins are a serious problem because:

 

                  a.  people often ingest them when they accidentally mistake the mushroom that produces them, for a similar looking edible mushroom

                  b. they are potent carcinogens

                  c.  they are produced as a byproduct by the important industrial fungus Aspergillus niger

                  d.  they contaminate food stuffs like peanuts and cottonseed oil

 

13.         More visible symptoms of fungal infection of humans are appearing recently because

                 

                  a.  more people live in areas that contain endemic organisms

                  b.  pathogens have mutated to increased virulence on humans

                  c.  new pathogens are being identified as the source of infections

                  d.  more people are getting opportunistic infections because more people have suppressed immune systems

 

14.               Signs of a Fungal Plant pathogen on a host plant may include

 

a.      necrosis of infected tissues

b.      wilting of the plant

c.       conidia

d.      sporangiospores

e.      hyphae

 

15.          Lichens

 

a.      require moist environments for growth

b. are fungal pathogens of algae

                  c.  are a mutualistic relationship between a photobiont and a mycobiont

                  d.  are the relatives of the  U of A president

                  e.  often indicators of pollution because they concentrate toxins

                  f.  an important source of food for Rudolph and his reindeer friends

 

16.         Fungal parasites of insects

 

                  a.  are found in several fungal phyla

                  b.  are proposed to be useful to control insect infestations

                  c.  is usually the species that the ants find on nearby vegetation

                  d.  break down leaf cellulose thus providing food for the ants

                  e.  keeps other fungi and bacteria out of the nest by producing antibiotics

 

17.          Fungi which reproduce only by asexual means, and produce conidia

 

                  a.  are unable to undergo mitosis

                  b.  are members of the Deuteromycota

                  c.  lack an anamorphic phase

                  d.  lack a telomorphic phase

 

18.          The fungus-like organisms of the kingdom Fungi differ from those in the kingdom Stramenopila by

 

                  a.  having a cell wall

                  b.  containing cellulose in their cell walls

                  c.  the pathway they use to synthesize lysine

                  d.  their lack of a plasma membrane

                  e.  if they have motile cells, those have whiplash flagella

 

19.          Saprobes are essential to life on earth because they

 

                  a. grow in association with the roots of most plants, providing scarce minerals to the plants

                  b.  are removers of debris that other organisms produce

                  c.  are fungi that live on trees and particularly digest the sap in the phloem

                  d.  recycle organic material to produce inorganic compounds

                  e. consume C02 which would otherwise build up to toxic levels (greenhouse gas)

 

20.          A difference between a conidium and a sporangiospore is

 

                  a.  conidia are asexual spores while sporangiospores are sexual spores of the Sporangiomycota

                  b.  only sporangiospores are formed by division of the cytoplasm within an existing cell followed by wall delineation

                  c.  conidia are never motile cells, while all sporangiospores are motile

                  d.  conidia contain chitin in their cell walls, while sporangiospores may have either chitin, or cellulose

 

21.          A gametangium is

 

                  a.  known as an oogonium or an antheridium in the Oomycota

                  b.  the nucleus that travels from the antheridium through the trichogyne

                  c.  the site of meiosis in the Oomycota

                  d.  the site of meiosis in the Ascomycota

                  e.  the sexual spore of the Gametangiomycota

                  f.  also known as a planogamete in the Chytridiomycota

 

22.          Exogenous dormancy is a condition that

                 

                  a.  may be due to a lack of water

                  b.  requires a short trigger to break dormancy and allow spores to germinate

                  c.  is imposed on a spore by the environmental conditions

                  d.  may be due to the presence of self-inhibitors of germination

                  e.  requires the factors that allow for the breaking of dormancy to remain present for continued growth

 

 

 

23.          Absorptive nutrition

 

                  a.  is when fungi absorb CO2 and N2 from the atmosphere for food

                  b.  means that fungi engulf their food and digest it inside their cytoplasm

                  c.  is when fungi secrete digestive enzymes that break down organic matter externally

                  d.  requires external water

 

24.          Heterothallic fungi may

 

                  a.  be self-sterile

                  b.  be self-fertile

                  c.  mate using a bipolar or tetrapolar mating system

                  d.  be found among in the Deuteromycota

                  e.  be hermaphrodites

 

25.          Fungi in the generaRhizopus, Aspergillus. and Penicillium

 

                  a.  are found everywhere because they produce large numbers of aerially dispersed spores

                  b.  are all found in the form-phylum Deuteromycota

                  c.  are in different phyla because Rhizopus  sp. produce sporangiospores

                  d.  are in different kingdoms because Rhizopus sp. produce motile sporangiospores

                  e.  all contain species that are important for industry

 

26.          A plasmodium

 

                  a.  is multinucleate

                  b.  has haploid nuclei

                  c.  is multi-cellular

                  d.  feeds by phagocytosis

                  e.  is found in the Myxomycota

                  f.  has cell walls to support its massive structure

 

27.          Asexual reproduction is important to fungal survival because

 

                  a.  many spores are produced that can act as dispersal units

                  b. it often produces new genotypes through genetic recombination

                  c.  it can occur rapidly and multiple times per growing season

                  d.  it produces resistant resting spores such as zygospores and oospores

 

28.          The Myxomycota are placed in the kingdom Protoctista, not the kingdom Fungi because

 

                  a.  they have motile cells

                  b.  they lack cell walls in their vegetative stage

                  c. they do not produce conidia

                  d.  they feed by engulfment, not absorption

29.          The extended dikaryon of the Basidiomycota

 

                  a.  means that each cell has two haploid nuclei of compatible mating types

                  b.  means that each cell has a single haploid nucleus, but adjacent cells have different nuclei, creating an ÒextendedÓ cell

                  c.  means that a long part of the life cycle is diploid

                  d.  is maintained by the formation of clamp connections

                  e.  is initially formed by fusion between hyphae of compatible mating types

 

30.          The difference between the nuclear DNA content of hyphae in the Zygomycota and the Oomycota is

                 

                  a.  the Zygomycota are aneuploid and the Oomycota haploid

                  b.  the Zygomycota are haploid and the Oomycota dikaryotic

                  c.  the Zygomycota are haploid and the Oomycota diploid

                  d.  there is no difference

 

31.          Ascocarps may be

 

                  a.  present or absent in the Ascomycota

                  b.  known as a cleistothecium

                  c.  known as an apothecium

                  d.  known as an acervulus

                  e.  dikaryotic

                  f.   haploid

 

Extra credit:  For the correct structure(s) in 32, what is the name of the fungal class that contains that structure. For the incorrect structure(s), what is it for? (0.5 points each)

 

32.          Basidiomycetes known as smuts (Ustilaginales), are similar to the rusts Uredinales) because they

 

                  a.  are both serious plant pathogens

                  b.  both often have a lifecycle that requires more than one host

                  c.  both produce intercalary teliospores that replace the host organ

                  d.  both lack a basidiocarp

                  e.  are both obligate pathogens throughout their lifecycle

                  f.  both produce resistant teliospores

 

33.          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

TRUE/FALSE:  write True or False to the LEFT of each answer (1.0 point each)

 

An auxotroph is a strain that is unable to grow on minimal medium without supplements

 

Homologous chromosomes pair in the parasexual cycle

 

Many more species of fungi are animal pathogens than are plant pathogens

 

The number of ascospores per ascus varies depending on how many rounds of mitosis occur following meiosis

 

In both the Ascomycota and the Basidiomycota, karyogamy does not generally proceed immediately after plasmogamy

 

Coprophilous fungi are likely to be passively discharged and aerially dispersed

 

A tetrad is the group of spores that represents the products of a single meiotic event

 

All edible mushrooms are from the phylum Basidiomycota

 

In most places it is illegal to possess spores or mycelia of hallucinogenic mushrooms. 

 

Short Answers:  Answer questions 1 through 7, and then a subset of the rest, as listed

 

1.             In Medical Mycology, what is the difference between a "real" or endemic pathogen and an opportunistic pathogen?  How do most real human pathogens gain entry into the human body?  Why do many people not realize they have been infected?   (3 points)

 

 

 

 

 

 

 

 

 

 

2.             In the Daily Wildcat a few years ago, there was a (ridiculous) statement that Coccidioides immitis is similar to a bacterium but it has a different life cycle.  From what you have learned in Mycology, list three reasons why C. immitis is not similar to any bacterium.  (3 points)

 

 

 

 

 

 

3.             Explain how the timing of plasmogamy, karyogamy and meiosis relative to the asexual growth phase of a fungus determines whether a fungus is haploid, dikaryotic or diploid during its asexual life cycle.  You may use diagrams to support your explanation.  (4.5 points)

 

 

 

 

 

 

 

 

 

 

 

4.            What do a dikaryon and a heterokaryon have in common?  How are they different?  (2 points)

 

 

 

 

 

 

 

 

 

5a.        It was published that a Chytridiomycota species, that was reported to be responsible for the deaths of many frogs, is spreading at a rate of 19 miles a day in Central America (Discover Magazine, 1998). Although the spores of some fungal species have been demonstrated to be dispersed hundreds of miles in one day, explain why it is unlikely that this species spread at this rate. (2 points)

 

 

 

 

 

 

5b.  What types of species could spread at that rate and why?  (2 points)

 

 

 

 

 

5c.  Can you think of a scenario that would allow a Chytridiomycota species to spread this rapidly?  (1 point)

 

 

 

 

6.    While home on Winter break your parents show you a dying plant in their garden that has necrotic lesions on it.  You want to demonstrate your newfound knowledge of Mycology and tell them you will determine what caused the disease.  You then isolate three fungal species from the infected plant. 

 

a.            Your initial observations only allow you to tell what the nuclear ploidy of the hyphae are.  One (Strain X) is haploid, one (Strain Y) is dikaryotic and the other (Strain Z) is diploid.  From this initial information, you believe one is from the Oomycota, one from the Basidiomycota and one from either the Ascomycota, the Deuteromycota or the Zygomycota.  Explain which strain you think is from which phylum/phyla and why.  (3 points)

 

 

 

 

 

 

 

 

b.            Next you are able to observe all internal features of the hyphae.  What do you look for in strains X, Y and Z to support your initial diagnosis.  (2 points) (Explain for each strain).

 

 

 

 

 

 

 

 

 

c.            You believe that one of the strains is a true pathogen of the plant while the other two just colonized dead plant tissue after the initial infection.  What steps do you need to take to demonstrate this? (3 points)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7.             Matching:  Place the correct letter from the right hand column by the correct phylum in the left hand column.  (1.5 points per answer)

 

Ascomycota                                                                         a) Hyphae septate with simple septa, asexual spores are conidia, sexual spores contained in a sac

 

Hyphochytriomycota                                                     b) cellulose in cell walls, has a single anterior tinsel flagellum

 

Zygomycota                                                                          c) septa are dolipore, long-lived dikaryotic vegetative phase

 

Dictyosteliomycota                                                        d) cellulose in cell walls, coenocytic hyphae, biflagellate zoospores

 

Oomycota                                                                               e) chitin in cell wall, zoospores with posterior whiplash flagellum

 

Myxomycota                                                                         f) chitin in cell wall, coenocytic, no zoospores haploid through most of its life cycle

 

Chytridiomycota                                                                g) assimilative stage lacks cell wall; plasmodial stage free-living

 

Deuteromycota                                                                  h) assimilative stage lacks cell wall;  has a pseudoplasmodium

 

Basidiomycota                                                                    i) chitin in cell wall, no known teleomorph

 

 

8.             Answer the questions for TWO of the three life cycles presented: A, B, or C.  (7 points)

 

A.            Life Cycle One:  Saccharomyces cerevisiae

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.             Label where plasmogamy, karyogamy and meiosis take place on the diagram on page 10. 

 

 

2.             Where does mitosis take place?.

 

 

3.            What is the structure labelled ÒAÓ?

 

 

4.             How do the two arrowed circles on the left and right of this diagram tell you it is diplobiontic?

 

 

EXTRA CREDIT:  Name another diplobiontic fungus and its phylum (2 points)

 

 

 

 

B.            Life Cycle Two:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.             Label the following structures

 

                  a.  antheridium

                  b.  primary cyst

                  c.  secondary zoospore

                  d.  oogonium

                  e.  sporangium

                  f.  oosphere

 

2.             Which of the above structures are diploid? Which are haploid?

 

3.             Where does meiosis take place in this life cycle? 

 

4.            Where does mitosis take place in this life cycle?

 

5.             EXTRA CREDIT:  (2 points)  What is the phylum of this organism?  List two features, from this figure, that tell you this is the case.

 

 

 

C.            C.            Life Cycle Three:  Wheat stem rust

 

Spore                           nuclear ploidy

 

a.                                                                                    

 

b.                                                                                   

 

c.                                                                                    

 

d.                                                                                   

 

e.                                                                                   

 

 

 

 

 

1.             Name the spores that are marked "a" to "e"

2.             Which of these spores are haploid? dikaryotic, diploid?.

3.            Which of these spores infect wheat?

                  Which infect barberry?

                  Are there any that do not infect either plant? 

4.             Label where plasmogamy, karyogamy and meiosis occurs.

5.            In the Basidiomycota there are two different systems for separating species into Classes. Name one of the Classes to which this species belongs and explain your choice. (2 points)

 

 

 

 

 

ANSWER EITHER  QUESTION 9 OR 10 (5 points)

9.             Cyclosporin A was isolated from a fungus for use as an antifungal drug.

a.  Why did it turn out to be a very bad antifungal drug?    For what is it currently used?

 

 

 

b. What is the general mode of action of Cyclosporin A?

 

 

 

                  c. From what fungus was it isolated?

10.         The fungus Claviceps purpurea produces a series of compounds known as the ergot toxins. 

 

                  a.  What are some of the modes of action of these toxins? 

 

 

 

 

                  b.  How are some of these compounds used in medically beneficial ways?

 

 

 

 

                  c.  What stage of the fungus is responsible for toxin production and how is it ingested? 

 

 

 

 

 

 

ANSWER EITHER QUESTION 11 OR 12 (4 points)

11.          Two fungi, Cryphonectria parasitica and Penicillium roquefortii may be used to produce roquefort cheese.  What is the role of each fungus in this process?

 

 

 

 

 

 

 

 

12.          a.  Does passive dispersal or forcible discharge of spores generally result in further dispersal of fungal spores?  Explain.

 

 

 

 

 

 

 

                  b.  Give an example of a fungus and describe its mode of nutrition that uses only forcible discharge of spores.

 

 

 

 

 

 

ANSWER TWO of The Following THREE QUESTIONS 13, 14 and 15. (4 points)

 

13. Why is it easier to develop drugs (that don't harm the host) to kill bacterial pathogens of humans than to kill fungal pathogens?  (2 points)

 

 

 

                  b. Give an example of a good target in fungi for development of an antifungal drug. Explain your answer

 

 

 

14.          a.  From what was Citric Acid isolated before it was isolated from a fungus? 

 

 

 

                  b.  From what fungus is citric acid isolated now?

 

 

                  c.  What features of fungal growth are controlled to get the best production of citric acid?

 

 

 

 

                  d.  What are three uses for citric acid?

 

 

 

 

 

15.          Why was Saccharomyces cerevisiae a good choice as the first eukaryote to be sequenced? 

 

 

 

 

b.             Is the majority of  the sequence coding or non-coding regions?  What does that mean? 

 

 

 

c.             What is GC content, and is it uniform throughout the yeast genome?  Explain.

 

 

 

Definitions:  (1.5 points each)

saprobe

 

 

holocarpic

 

 

mycorrhizal fungus

 

 

psilocin

 

 

zoosporangium

 

 

haustorium

 

 

hermaphrodite

 

 

EXTRA CREDIT:

There may be three different fungal species or fungal products involved in production of a tart, fruit-filled jelly donut.  What are they and what did they contribute? (3 points)

 

 

 

 

 

 

 

                  AND FINALLY:  Your chance to ask and answer that question that you studied for in detail and I neglected to ask you (1-6 points based on detail, answer on back).