UNIVERSITY OF LIMPOPO
TURFLOOP CAMPUS
FACULTY OF SCIENCE AND AGRICULTURE
SCHOOL OF MOLECULAR AND LIFE SCIENCES
DEGREE AND DIPLOMA EXAMINATIONS
MODULE:
MICB 202
OCT/NOV
:
(ENVIRONMENTAL AND FUNGAL MICROBIOLOGY)
2012
TIME:
3 HOURS
PAPER
:
P1
MARKS
:
100
INTERNAL EXAMINERS
:
PROF EL JANSEN VAN RENSBURG
PROF P MASOKO
SECOND EXAMINER
:
PROF E ABOTSI
THIS PAPER CONSISTS OF …8…PAGES INCLUDING COVER PAGE
MEMORANDUM
INSTRUCTIONS:
1. Answer all the questions
2. Write neatly and legible
MICB202 OCTOBER/NOVEMBER EXAMINATIONS
2012
SECTION A (50 MARKS)
QUESTION 1 (9 marks)
1.1 The simple fungi consist of three phyla and produce moving
spores. List the phyla and explain how you will differentiate
between the three phyla.
(6)
Chytridiomycota – zoospore with one posterior whiplash flagellum
Hyphochytriomycota – zoospore with one anterior tinsel flagellum
Oomycota – zoospore with two flagella, one whiplash and one
tinsel
1.2 What is the difference between
1.2.1 sporangiospores and conidia?
(1)
Sporangiospores are produced in a sporangium as free cells and
conidia are budded out or converted from existing cells
1.2.2 zygospores and ascospores?
(1)
Zygospores are sexual spores produced by Zygomycota. Spores
are produced in a zygosporangium.
Ascospores are sexual spores produced by Ascomycota. Spores
are produced in specialized structures called asci.
1.2.3 oospore and oosphere?
(1)
Oospore is a thick walled resting spore developing from a fertilized
egg of the Oomycota
Oosphere is the unfertilized female gamete (egg) produced by the
oogonium
QUSTION 2 (17 marks)
2.1
Name the four kinds of asci you will associate with the
Ascomycetes and differentiate between them.
Unitunicate-operculate ascus
Asci with a single wall with a operculum
Unitunicate-inoperculate ascus
Asci with a single wall with no operculum
2
(8)
UNIVERSITY OF LIMPOPO
Prototunicate ascus
Closed ascus and the walls lysed at maturity
Bitunicate ascus
Asci with two wall layers
2.2 You have isolated a pathogen from rye and the following drawings
were made studying the pathogen.
2.2.1 Give the labels indicated by A to C by writing the letter with
corresponding answer in your answer book.
(3)
A- perithecium
B- compound ascomata (ascoma)
C- ergot
2.2.2 Indicate the classification of this fungus regarding the Order,
Class and Phylum names and give the differentiating
characteristic for each of these levels.
Order: Clavicipitales (obligate parasites; stalked fungal stroma)
Class: Ascomycetes (produce asci in fruting bodies)
Phylum: Ascomycota (produce ascospores in an ascus)
QUESTION 3 (12 marks)
(6)
3
MICB202 OCTOBER/NOVEMBER EXAMINATIONS
2012
You have picked four kinds of fungal fruiting bodies and made the
drawings as indicated below. The following questions relate to these
diagrams.
3.1 Give the labels indicated by E to J by writing the letter with
corresponding answer in the answer book.
(6)
E – volva
F – pileus
G – ring
H – stipe
I – reticulum
J - tubes
3.2 Indicate the possible family names, A – D, you would associate
with these fungi by writing the letter and answer in your book.
(4)
A – Amanitaceae
B – Agaricaceae
C – Coprinaceae
D - Boletaceae
3.3 Give the Class name for these fungi and indicate the differentiating
characteristic you would associate with this Class.
Holobasidiomycetes producing holobasidia (basidia with septa)
4
(2)
UNIVERSITY OF LIMPOPO
QUESTION 4 (12 marks)
4.1 Illustrate with descriptions how you would differentiate between the
two types of mycorrhiza.
(6)
(1)
(1)
(1)
(1)
(1)
(1)
4.2
What is the fungus (genus name) you will associate with the
following toxins?
4.2.1 Aflatoxins
Aspergillus
4.2.2 Zearalenone
Fusarium
4.2.3 Sporidesmin
Pithomyces
4.2.4 Amatoxins
Amanita
4.2.5 Orellanine
Cortinarius
4.2.6 Gyromitrin
Gyromitra
5
MICB202 OCTOBER/NOVEMBER EXAMINATIONS
2012
SECTION B (50 marks)
QUESTION 1(20 marks)
Choose the most correct answers from the questions below and
provide your answers on the provided multiple choice answer sheet.
1.1. An association in which one population of organisms benefits
while the other is neither harmed nor helped is called a
_____________________ association.
A.
Parasitic.
B.
Protocooperative.
C.
Commensalistic.
D.
Symbiotic.
E.
Mutualism.
1.2. _________________ describes the negative effect that one
organism has on another organism because of the release of a
specific compound that detrimentally effects the second
organism.
A.
Amensalism.
B.
Protocooperation.
C.
Commensalism.
D.
Parasitism.
E.
Mutualism.
1.3. What would ultimately happen to the biosphere if
microbiologically mediated methane oxidation would cease to
exist?
A.
Since all biogeochemical cycles are stable, homeostasis would
continue to prevail.
B.
CO2 would accumulate to a level in which the greenhouse effect
would heat and kill all life.
C.
CH4 would accumulate and corresponding CO2 levels would
decline, significantly diminishing photoautotrophic primary
productivity needed to sustain life on earth.
6
UNIVERSITY OF LIMPOPO
D.
Nitrogen fixing bacteria would rise in dominance to become the
most abundant group of microorganisms within the biosphere.
E.
None of the above consequences would happen.
1.4.
Addition of nitrogen containing fertilizers affects gas exchange
processes in the soil…
A.
Causing methane gas to be consumed.
B.
Causing methane gas to be produced.
C.
Causing release of NO and N2O, which are greenhouse
gasses.
D.
Causing antibiotic production in bacteria which lead to
antiobiotic resistance.
E.
Causing assimilation of NO3 by the plants.
1.5.
Microbial immobilization of the sulfur compounds and
subsequent incorporation into the organic form of sulfur are
often termed as follows, except...
A.
Assimilative sulfate reduction, in which sulfate (SO42–) is
reduced to organic sulfhydryl.
B.
Oxidation of hydrogen sulfide produces elemental sulfur (So).
C.
Dissimilative sulfur oxidation in which elemental sulfur can
be reduced to hydrogen sulfide.
D.
Dissimilative sulfur reduction in which elemental sulfur can be
reduced to hydrogen sulfide.
E.
Dissimilative sulfate reduction in which sulfate reducers
generate hydrogen sulfide from sulfate.
1.6.
__________ is the genus that carries out nitrogen fixation,
which is the conversion of ____________.
A.
Azotobacter; ammonia to nitrogen gas
B.
Rhizobium; nitrite to nitrate
C.
Nitrosomonas; nitrate to nitrite
D.
Nitrobacter; nitrite to nitrogen gas
E.
Rhizobium; nitrogen gas into ammonia
1.7.
Which statement about methanogenesis is not true?
A.
Methanogenesis in microbes is a form of anaerobic respiration.
7
MICB202 OCTOBER/NOVEMBER EXAMINATIONS
2012
B.
Methanogens do not use oxygen to respire.
C.
Methanogenesis is the final step in the decay of organic matter.
D.
The terminal electron acceptor in methanogenesis is not
oxygen, but carbon.
E.
During advanced stages of organic decay, all electron
acceptors become depleted, except oxygen.
1.8.
What group of microorganisms carries out methanogenesis?
A.
Group of strictly anaerobic Archaea.
B.
Gram-positive bacteria.
C.
Facultatively aerobic Gram-negative bacteria.
D.
Group of strictly anaerobic Gram-negative bacteria.
1.9.
Electrons for the reduction of CO2 to CH4 come mainly from…
A.
CO2.
B.
Ferric iron.
C.
Glucose.
D.
H2.
1.10. Methanogenesis is an example of..
A.
Aerobic respiration.
B.
Anaerobic respiration.
C.
Substrate-level phosphorylation.
D.
Photophosphorylation.
1.11. Which of the following is NOT characteristic of a coliform?
A.
Facultatively aerobic
B.
Gram-negative.
C.
Rod shaped.
D.
Ferment glucose with the formation of gas.
E.
All of the above.
1.12.
What is the medium used in the membrane filter (MF) procedure
to differentiate fecal coliforms and Escherichia coli?
A.
Mannitol salt agar.
B.
Eosin-methylene blue agar.
8
UNIVERSITY OF LIMPOPO
C.
Triple sugar iron agar.
D.
Blood agar.
E.
MacConkey agar.
1.13.
Which treatment method(s) are used in primary wastewater
treatment?
A.
Biological.
B.
Chemical.
C.
Physical separation.
D.
All of the above.
1.14.
During secondary aerobic wastewater treatment, some of the
activated sludge goes ________ while the rest goes ________.
A.
back to the aerator / to the anoxic sludge digestor.
B.
back to the primary system / to the aerator.
C.
to the anoxic digestor / back to the primary system.
D.
back to the primary system / to the tertiary digestor.
1.15.
Which statement explains the relationship between coagulation
and flocculation?
A.
Coagulation leads to flocculation.
B.
Flocculation leads to coagulation.
C.
Coagulation occurs after filtration.
D.
Flocculation occurs after filtration.
Question 1.16 to 1.20, indicate if the statement is TRUE (A) or False
(B)
1.16.
Microbes that can dissimilate sulfur can also assimilate it, but
not all that assimilate sulfur can fully dissimilate it. A
1.17.
Methanogens, among other compounds, use alcohols and fatty
acids to synthesize methane gas in anoxic environments. B
1.18.
The most dominant aquatic and terrestrial phototrophs are
phototrophic microorganisms. B
1.19.
Wastewater plants are usually constructed to handle both
domestic and industrial wastes. A
1.20.
In water, most taste- and odor-producing compounds are
inorganic in nature. B
QUESTION 2 (14 marks)
9
MICB202 OCTOBER/NOVEMBER EXAMINATIONS
2012
Phosphorus (P) is an essential nutrient for plants and animals in the
form of ions and it forms parts of important life-sustaining molecules
that are very common in the biosphere.
2.1.
Mention two processes which can be used to remove excess
phosphorus.
(2)
Chemically through precipitation
Biological by Acinetobacter calcoaceticum
2.2.
Mention two purposes of phosphorus.
(2)
Prevent sewage to cause eutrophication
Produce a valuable product
2.3.
During rainy seasons P is washed into the sea. How is it
returned to the land ?
(2)
Faeces from seabirds (small amounts)
Geological uplift of ocean floors (process slow)
2.4.
Briefly describe how Acinetobacter calcoaceticum remove P
from the environment.
(8)
aerate pond with small quantities of sewage (carbon)
Acinetobacter accumulates polyphosphate in cells
Remove carbon source
Turn pond to anaerobic conditions
Reduce volume in pond
Results in Acinetobacter to utilize polyphosphate
Phosphate ions released into water
Water with high posphate sold to detergent company
QUESTION 3 (16 marks)
3.1. List the type of wastewater treatment in the following processes:
10
3.1.1
Chemical precipitation of phosphorus. Tertiary
(0.5)
3.1.2
Removal of solids. Primary
(0.5)
3.1.3
Activated sludge. Secondary
(0.5)
3.1.4
Trickling filter. Secondary
(0.5)
UNIVERSITY OF LIMPOPO
3.2. Briefly explain how organic materials are oxidized by microbes
during the activated sludge process.
(9)
Sewage mixed with slime forming bacteria
Zoogloea + heterotrophic bacteria
Mixture is aerated
Large flocs or clumps form
Heterotrophs oxidize organic material
Treated water moved to settling tank
Floc settle out and is recycled
Reduce BOD by up to 90% (25 – 30mg/l)
Contain high levels of inorganic material
3.3. Describe how microbial leaching is used in the mining of copper.
(5)
Chemically purifying copper ions in a mine can be very costly, so
microorganisms can be exploited in the mining of metals such as copper.
Solid copper compounds (e.g., CuS) at a low concentration in the ore are
leached into water-soluble copper (Cu2+) by sulfuric acid being passed
through the ore. Acidithiobacillus ferrooxidans catalyzes the oxidation of
the CuS, which helps to leach Cu2+. Solid copper is then precipitated
from the leachate.
11