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AMB821S - ADVANCED MICROBIOLOGY - 1ST OPP - NOVEMBER 2024 |
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nAm I BI A UnlVERS ITV
OF SCIEnCE AnDTECHnOLOGY
FacultyofHealth,Natural
ResourceasndApplied
Sciences
Schoolof Natural andApplied
Sciences
Department of Biology,
Chemistryand Physics
n JacksonKaujeuaStreet
Private Bag13388
Windhoek
NAMIBIA
T: •264612072012
F: •264 612079012
E: dbcp@nust.na
W: www.nust.na
FIRST OPPORTUNITY EXAMINATIONS
QUALIFICATION: BACHELOR of SCIENCES HONOURS
QUALIFICATION CODE: 0SBOSC
LEVEL:8
COURSE:ADVANCED MICROBIOLOGY
COURSECODE: AMB821S
DATE: NOVEMBER 2024
SESSION: 1
DURATION: 3 HOURS
MARKS: 100
EXAMINER:
MODERATOR:
Mr Petrus Tuhafeni Paulus
Prof Jane Misihairabgwi
INSTRUCTIONS
1. Answer all questions in section A and any two questions from section B.
2. Each question must be answered on the separate answer sheet.
3. Please write neatly and legibly.
4. Do not use the left side margin ofthe exam paper. This must be allowed for the
examiner.
5. No books, notes and other additional aids are allowed.
6. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIALS
1. Non-Programmable Calculator
This PAPER consists of 6 pages including this front page
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SECTION A: [60 MARKS]
QUESTION 1 (20)
1. In 1872, Frans Schrandinger proposed that E.coli could be used to indicate that water is
contaminated with feaces.
1.1.1 Briefly outline the main reason why E. coli was chosen as a test microorganism for the
presence of contaminants in feaces.
(3)
1.1.2 Propose a method that could be used for the isolation and enumeration of coliforms
from contaminated water.
(4)
1.1.3 Testing for coliforms is sometimes accompanied by biochemical test such as IMViC.
What is the principle underlying the IMViC test in microorganisms?
(7)
1.1.4 Discuss how a selective and differential media can be combined in the identification
of bacteria by biochemical methods.
(6)
QUESTION 2 (20)
2.1 Jane is fourth year B.Sc. Honours student, and she did an experiment to analyse the
microbial load of water samples using the Most Probable Number (MPN) method in
her laboratory. Jane used the MPN table (illustrated in table 1) and got an MPN of 9.2
per 100 ml.
Advanced Microbiology (AMB 8215)
1'1 Opportunity November 2024
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Tablel: Table of the most Probable Number {MPN) per 100ml of sampling using three tubes
of each dilution
Number of positive tubes in dilutions
10ml
1ml
0.1 ml
MPN per 100 ml
0
0
0
0
1
0
3
0
0
3
6
0
1
0
3
0
1
1
6.1
0
1
2
9.2
0
1
3
12
2.1.1 Briefly describe the principle and procedure of MPN that she used to arrive at an MPN
of 9.2 per 100 ml.
(8)
2.1.2 What are the disadvantages of MPN method as a diagnostic tool in
microbiological samples.
{3)
2.2 Outline the principle of protein evolution in industrial microbiology.
(9)
QUESTION 3 (20)
3.1 You wish to determine the number of bacteria in an actively growing broth culture of
E. coli. To do this you remove 1.0 ml of the culture from the flask and dilute this in 9
ml of nutrient broth to obtain 10·1 dilution. You then serial dilute the sample further
AdvancedMicrobiology (AMB 821S)
1st Opportunity November 2024
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until you obtain a range of dilutions between 10-2 and 1o-6. From each dilution you then
spread plate 0.1 ml of suspension onto the nutrient agar and incubate overnight. The
next morning you have the following results.
Plate
Dilution
Colonies on plate
number
1
Neat
Too many to count
2
10-1
Too many to count
3
10-2
Too many to count
4
10-3
280
5
10-4
27
6
10-s
2
7
10-6
0
Determine how many bacteria per ml there were in the original sample taken from the
overnight culture.
(5)
3.2 You adjust the density of the cell suspension so that there are I x 106 bacteria per ml in
broth and add 1 ml of this to a new culture flask. Assuming exponential growth and a
doubling time of 30 minutes, how many bacteria will be in the flask after 5 hours.
Show your working.
(5)
3.3 A minimum inhibitory concentration (MIC) test was carried out using the overnight
results and the MIC was found to be 3.1 µg/ml of Ampilicin drug. Briefly detail how
the test is performed.
(I 0)
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1'1 Opportunity November 2024
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SECTION B [40 MARKS]
Answer only two questions from this section. Each question carries 20 marks
QUESTION 4 (20)
4.1 Outline the main characteristics to be considered when selecting an organism for
industrial use.
(4)
4.2 Briefly define the term coliforms and their role in the diagnostics of wastewater
treatment.
(8)
4.3 Discuss how protoplast fusion has been used to manipulate microorganism genetically
for industrial use.
(8)
QUESTION 5 (20)
5.1 The basic reproductive number, (Ro),defines the mean number of individuals directly
infected by an infectious case through the total infectious period, when introduced to
a susceptible population is given by the equation
• Ro= p. C. d
Define the terms p, c, d and how they can be used to combat infections such sexually
transmitted diseases (STI).
(4)
5.2 Briefly evaluate the implication of Ro as used in epidemiology.
(6)
5.3 Discuss five factors leading to the emerging of infectious diseases in the 2ist century.
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QUESTION 6 {20)
6.1 Outline the benefits of human gut microbiome.
(10)
6.2 Briefly describe the changes in antibody concentrations following the initial dose of Covid-
19 jab and how that leads to conferment of long-lasting immunity to an individual. (10)
QUESTION 7 {20}
7.1 Discuss the role of lactic acid bacteria in the production of hard cheese such as Gouda.
(10)
7.2 A conglomerate Mine in Southern part of Namibia has been mining, copper, gold,
manganese and iron for the past 60 years using conventional open pit and later
underground mining methods. The management of the mine are contemplating the
closure of the mine since the minerals are now of low grade. However, one the
directors of the mine still believes that the life of the mine can be extended by 50 years
if they venture into other methods of mining. You have been hired as a consultant to
give advice on how they can utilize other methods to mine the low-grade ores and
extend the life of the mine. Detail the advice you will give to the mine authorities to
convince them to continue to mine at the same premises.
(10)
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END OF EXAM
Advanced Microbiology (AMB 821S)
1st Opportunity November 2024
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