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MIB701S - MICROBIOLOGY - 1ST OPP - JUNE 2023 |
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r
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nAmI BIA un IVE RSITY
OF SCIEn CE TECHn OLOGY
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
SCHOOLOF HEALTHAND APPLIEDSCIENCES
DEPARTMENTOF BIOLOGY,CHEMISTRYAND PHYSICS
QUALIFICATION: BACHELOROF SCIENCE
QUALIFICATION CODE: 07BOSC
LEVEL: 7
COURSECODE: MIB701S
COURSENAME: MICROBIOLOGY
SESSION:JUNE 2023
DURATION: 3 HOURS
PAPER:THEORY
MARKS: 100 MARKS
FIRST EXAMINATIONS OPPORTUNITY QUESTION PAPER
EXAMINER(S) DR. MUNYARADZI ZIVUKU
MODERATOR: PROF.JANE MISIHAIRABGWI
INSTRUCTIONS
1. There are FIVE questions on this paper. Answer ALL the questions.
2. The number of marks are given in brackets () at the end of each
question or part question.
3. Write clearly and neatly.
4. Number the answers clearly.
THIS QUESTION PAPERCONSISTSOF 4 PAGES(Including this front page)
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SECTION A
[40]
QUESTION 1
(20)
1.1 Differentiate between Gram positive and Gram-negative
bacteria.
(4)
1.2 "Bacteria show a great deal of diversity in their requirements for
oxygen". Evaluate the categories or groups of bacteria based on
oxygen requirements.
(8)
1.3 Describe the main stages of bacterial growth curve.
(8)
QUESTION 2
(20)
2.1 Differentiate between selective media and differential media. (2)
2.2 Table 1.0 below shows the composition of Mannitol Salt Agar (MSA)
which is used as both a selective and differential media.
Composition of Mannitol Salt agar
Typical formula
Concentrations (g/1)
Beef Extract
1.0
Peptospecial
10.0
Sodium Chloride
75.0
Mannitol
10.0
Phenol red
0.025
Agar
15.0
pH = 7.4 at 25°C
Table 1.0: Composition of Mannitol Salt Agar (MSA)
(i) Evaluate the role of the ingredients in MSA.
(4)
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(ii) Discuss how MSA is able to select and differentiate specific
microorganism.
(4)
2.3 What is the basis of a pure culture technique?
(2)
2.4 Imagine you are working as a Junior microbiologist in a new
pharmaceutical research institute laboratory. Your supervisor asks
you to isolate Penicillum notatum from soil. Detail how you would
isolate and cultivate a microorganism for use in pharmaceutical
industry soil.
(8)
SECTION B
[60]
QUESTION 3
(20)
3.1 Given that E. coli has a generation time of 20 minutes. Determine the
microbial population after 3 hours given that the initial population was
having only three cells.
(4)
3.2 Briefly discuss the mechanism of how each of the following
methods are used for the control of microbial growth.
3.2.1 Heat
(4)
3.2.2 Radiation
(4)
3.3 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.
(8)
QUESTION 4
(20)
4.1 Define the term indicator microorganisms with examples and their
significance as diagnostic tools in municipal water testing
(4)
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4.2 Explain why it is advisable to monitor BOD before discharging raw
sewage into rivers.
(4)
4.3 Outline the main characteristics to be considered when selecting a
microorganism for industrial use.
(4)
4.4 Briefly discuss Bacillus thuringiensis or its toxin is used as a
pesticide in agriculture.
(8)
QUESTION 5
(20)
5.1 Discuss FIVE methods of maintenance and preservation of pure
cultures.
(10)
5.2 Outline the role of lactic acid bacteria in the manufacture of
fermented milk products such as Gouda cheese.
(10)
ENDOF QUESTIONPAPER
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