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MIB701S- MICROBIOLOGY - 1st Opp - JUNE 2022 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH, APPLIED SCIENCES AND NATURAL RESOURCES
DEPARTMENT: NATURAL AND APPLIED SCIENCES
QUALIFICATION : BACHELOR OF SCIENCE (MAJOR AND MINOR)
QUALIFICATION CODE: 07BOSC
LEVEL: 7
COURSE CODE: MIB701S
COURSE NAME: MICROBIOLOGY
SESSION: JUNE 2022
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
EXAMINER(S) | DR MUNYARADZI ZIVUKU
MODERATOR: | DR RONNIE BOCK
Instructions
1. Answer all questions in section A and any three questions from
section B
Answer the questions in the booklet provided
Write clearly and neatly
All written work MUST be done in blue or black ink
Mark all answers clearly with their respective question
numbers
THIS QUESTION PAPER CONSISTS OF 4 PAGES
(INCLUDING THIS FRONT PAGE)
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SECTION A
(40)
QUESTION 1
(20)
1.1
Define generation time.
(2)
12
Given that the generation time of E coli is 20 minutes. Determine the number of
E coli present after 3 hours if at the beginning there were only two cells.
(4)
1.3
Discuss the importance of D-value in the food industry.
(4)
1.4
Detail a procedure you would use to isolate (from wild) and culture an antibiotic
producing or an antibiotic resistant microorganism.
(10)
QUESTION 2
(20)
2.1
Discuss four methods of maintenance and preservation of pure cultures.
(8)
2.2 A microbiologist technician was given the following selective media —Brilliant green
selenite broth to isolate and identify some microorganism in the laboratory. The
composition of Brilliant Green Selenite broth are given in the table.
Composition of Brilliant green selenite broth
Typical formula (g/l)
PO Pt ers s cxcsws ss 345065 4 26088 6 noise eeemen e mms nem 5.0
D-Mannitol.........
0... ccccee cee cec eee ee ee eaeeeeeeeaes 5.0
Yeast Oxtracl, ; wnsees «canis a sreeg 2 240g ¥ eninne x esas onmee ne 5.0
Sodium selenite.....0..ce.e .cee.ee.e c.ee.ce.e n.ee.eees 4.0
Dipotassium phosphate............c.ee.c.ee.c.ec.e 2.65
Monopotassium phosphate....................00008 1.02
Brilliant Qre@Nn.............ccceeceeseceneeeeessesenseees 0.05
pH: 7.4+/- 0.2 at 25 degrees
2.2.1. State one type of organism isolated with brilliant green selenite broth
(1)
2.2.2 Evaluate the composition of BSG broth media in relation to its role in isolating and
Identification of specific microorganism.
(7)
2.3 The use of heat in the control of microbial growth and spread is widely used in medical
and industrial application. Briefly, give an analysis of the mechanism and its
effectiveness in the control of pathogens.
(4)
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SECTION B
(60)
Answer any three questions from this section. Each question carries 20 marks.
QUESTION 3
(20)
3.1
At some point in the development of microbiology, there was a challenge of linking
the causative agent of the disease to the disease itself. Briefly outline the various
lines of proof used by Robert Koch to link the pathogen and the disease.
(10)
3.2
A student carried out an experiment to demonstrate the growth patterns of bacteria
with different oxygen requirements when grown in MacConkey broth. The results the
student obtained are shown in Figure 1.
Z
bacteria
Figure 1: Growth patterns of different bacteria based on oxygen requirements.
Using the information in Figure 1, deduce the different types of bacteria based on the
oxygen requirements.
(10)
QUESTION 4
(20)
4.1
Describe the principle on which the Gram stain is based.
(3)
4.2
Explain why the oil immersion objective marked with black rings are immersed in lens
oil during use.
(2)
4.3
Differentiate between Gram positive and Gram-negative bacteria.
(5)
4.4
Evaluate the use of positive and negative staining techniques in the identification and
classification of bacteria.
(10)
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QUESTION 5
(20)
5.1
What is a fastidious microorganism?
(2)
5.1.2. How does the microbiologist overcome the challenges of culturing fastidious
microorganism. Give one example in your answer
(3)
5.2
Discuss the exchange of genetic information in bacteria.
(15)
QUESTION 6
(20)
6.1
Define the term indicator microorganisms and their significance as diagnostic tools in
municipal water testing
(3)
6.2
Explain why it is advisable to monitor Biological Oxygen Demand (BOD) before
discharging raw sewage into rivers.
(3)
6.3
Describe how Bacillus thuringiensis or its toxin is used as a pesticide in
Agriculture.
(6)
6.4
Describe the role of lactic acid bacteria in the manufacture of fermented milk
products such as cultured milk.
(8)
END OF EXAMINATION QUESTION PAPER