Download UNIVERSITI MALAYSIA PERLIS UJIAN 2 Semester Kedua Sidang

UNIVERSITI MALAYSIA PERLIS
UJIAN 2
Semester Kedua
Sidang Akademik 2010/2011
March 2011
ANSWER SCHEME
ERT 107 – MICROBIOLOGY FOR BIOPROCESS ENGINEERING
Masa : 1 jam
Please make sure that this question paper has 2 (2) printed pages including this front page
before you start the examination.
[Sila pastikan kertas soalan ini mengandungi DUA (2) muka surat yang bercetak termasuk muka hadapan
sebelum anda memulakan peperiksaan ini.]
This question paper has FOUR (4) questions. Answer ALL FOUR (4) questions.
[Kertas soalan ini mengandungi EMPAT (4) soalan. Jawab kesemua EMPAT (4) soalan.]
Question 1
i.
For naming or grouping microorganism in Microbiology, we have the natural,
phonetic, phylogenetic, and genotypic classifications. Write briefly on the best
classification you would choose for the microbial taxonomy stating its advantages.
ANSWER
Natural classification:
Arrange organisms into groups whose members share many characteristics.
First such classification in 18th century developed by Linnaeus - based on anatomical
characteristics
This approach to classification does not necessarily provide information on
evolutionary relatedness
Phonetic classification
Groups organisms together based on mutual similarity of phenotypes.
Can reveal evolutionary relationships that compares as many attributes as possible
except genetic characters
Phylogenetic classification, phylogeny or phyletic classification systems
Deals with evolutionary development of a species based on direct comparison of
genetic material and gene products using Woese and Fox’s proposal of using rRNA
nucleotide sequences to assess evolutionary relatedness of organisms.
Genotypic classification
Seek to compare the genetic similarity between organisms using genes or genomes
and a 70% threshold of homologous genomes for prokaryotes to avoid disrupting
existing species assignments.
[2 advantages x10=20 marks]
ii.
A student was brought to the hospital to seek treatment for diarrhea, stomach pain and
vomiting possibly caused by a microbe. Write the Linnaeus classification of the
suspected microbe.
[5 marks]
ANSWER
[Any one of the list below is associated with food poisoning]
(Genus and species – 2 marks; Phylum, class and family – 3marks)
Escherichia coli: Kingdom – Bacteria; Phylum – Proteobacteria; Class –
Gammaproteobacteria; Order – Enterobacteriales; Family – Enterobacteriaceae.
Salmonella enterica: Kingdom- Bacteria; Phylum- Proteobacteria; Class- Gamma
Proteobacteria; Order- Enterobacteriales; Family- Enterobacteriaceae.
Staphylococcus aureus: Kingdom - Bacteria; Phylum - Firmicutes; Class - Bacilli;
Order - Bacillales; Family – Staphylococcaceae.
Clostridium botulinum: Kingdom - Bacteria; Phylum - Firmicutes; Class -Clostridia;
Order - Clostridiales; Family –Clostridiaceae.
Vibrio cholerae: Domain- Prokaryota; Kingdom – Bacteria; Phylum - Proteobacteria;
Class- Gammaproteobacteria ; Order- Vibrionales; Family – Vibrionaceae
Aspergillus flavus: Domain – Eukaryota; Kingdom - Fungi; Phylum - Ascomycota ;
Sub-Phylum – Pezizomycotina; Class –Eurotiomycetes ; Order - Eurotiales ; Family
–Trchocomaceae
Question 2
a) Describe the FOUR functions of plasma membrane in the cell structure of
microorganisms.
[20 marks]
b) Classify bacteria based on the arrangement of polypeptidoglycan structure in the cell
wall.
[5marks]
1.
2.
3.
4.
Answer
a) Functions of plasma membrane
separation of cell from its environment
- It is the chief point of contact with the cell’s environment and thus is
responsible for much of its relationship with the outside world.
selectively permeable barrier
– some molecules are allowed to pass into or out of the cell
– transport systems aid in movement of molecules
location of crucial metabolic processes such as respiration, photosynthesis, and
the synthesis of lipids and cell wall constituents.
detection of and response to chemicals in surroundings with the aid of special
receptor molecules in the membrane
b) bacteria are divided into two major groups based on cell wall arrangement
Question 3
a) The Calvin cycle consists of THREE main phases that play an important role for CO2
fixation.
(i)
Explain the use of CO2 in cell metabolism.
[10 marks]
(ii)
Illustrate the major molecules conversion in each phase.
[15 marks]
Answer
(i)
- CO2 is used as sole carbon source for microbes to synthesize new
organelles and cells through the Calvin cycle.
- CO2 will be fixed during the carboxylation phase in Calvin cycle.
(ii)
1. Carboxylation phase is the addition of CO2 to ribulose-1,5bisphosphate (RuBP) catalyzes by rubisco, forming 2 molecules of 3phosphoglycerate.
2. reduction phase is the reduction of 3-phospho-glycerate to
glyceraldehyde 3-phosphate
3. Regeneration phase refer to the regeneration of RuBP and the
production of carbohydrates (e.g., fructose and glucose)
Question 4
i.
Recognize and describe the 4 factors that influence the effectiveness of the
antimicrobial treatment
[20 marks]
ii.
Describe the significance of microbial death rate in microbial control.
[5 marks]
ANSWER
i. Several factors influence the effectiveness of antimicrobial treatment.
1. Number of Microbes: The more microbes present, the more time it takes to
eliminate population.
2. Type of Microbes: Endospores are very difficult to destroy. Vegetative
pathogens vary widely in susceptibility to different methods of microbial
control.
3. Environmental influences: Presence of organic material (blood, feces, saliva)
tends to inhibit antimicrobials, pH etc.
4. Time of Exposure: Chemical antimicrobials and radiation treatments are
more effective at longer times. In heat treatments, longer exposure
compensates for lower temperatures.
[4pts x 5 marks=20]
ii. When bacterial populations are heated or treated antimicrobial chemicals, they usually
die at a constant rate. The significance of ‘microbial death rate’ is to determine the
initial microbe logarithmic population and the time taken for effective sterilization.
[5 marks]