Student No: Student Name:






















PERUSAL: 10 minutes














Remember to write your name on the answer books before attempting any questions


Attempt all questions. Write all your answers in the answer books provided.


Allocate your time wisely in relation to the number of marks assigned for each question and time available.






1. Answer any one (1) of the following questions.


(a) Microbes are morphologically, metabolically and physiologically diverse and are ubiquitous in nature. Provide evidence for this statement. Use labeled diagrams wherever appropriate.




(b) Compare, contrast and discuss the cell walls and cell membranes of the domains Bacteria, Eucarya and Archaea. Provide labeled diagrams wherever appropriate. (48 marks)



2. Write notes on and/or draw schematic diagrams for any six (6) of the following:


(a) Arrangement and structure of bacterial flagella.

(b) Pasteurization

(c) Sporulating bacteria

    1. Chlamydia
    2. Salmonella
    3. Filtration as a means of sterilization
    4. Prions and viroids
    5. Virus attachment and uncoating

(6 x 8 marks)



Questions 3 to 32 are multiple choice questions. Answer all questions. Write only the correct alphabet letter against the question number in your answer book.



3. Cells with a relatively complex morphology that have a true membrane-delimited nucleus are called:


(a) procaryotes

(b) eucaryotes

(c) urcaryotes

(d) nocaryotes



4. Acid-fast organisms such as Mycobacterium tuberculosis resist decolorization by an acid-alcohol wash because of the high concentration of _____ in their cell walls.


(a) proteins

(b) carbohydrates

(c) lipids

(d) peptidoglycan



5. When smears of microorganisms are stained the smear is heat fixed in order to:


(a) kill the organism

(b) attach the organism firmly to the slide

(c) both a and b

(d) neither a or b




6. The lipopolysaccharide (LPS) that is found in the other membrane of gram-negative bacteria is also known as:


(a) exotoxin

(b) teichoic acid

(c) murein

(d) endotoxin



7. Chemotaxis implies that bacteria:


(a) move towards an attractant

(b) move away from a repellent

(c) both a and b

(d) neither a nor b



8. The term used to describe bacteria that are shaped like curved rods is:


(a) coccus

(b) bacillus

(c) vibrio

(d) coccobacillus



9. Bacteria are called _______ if they can metabolise only methane, methanol, carbon monoxide, formic acid and a few related one-carbon molecules.


(a) methylotrophs

(b) carbotrophs

(c) monotrophic

(d) autotrophic



10. Mannitol salt agar (MSA) only allows the growth of halophiles. Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a _____ medium.


(a) selective

(b) differential

(c) both a and b

(d) neither a nor b



11. Organisms that do not require oxygen for growth but grow better in its presence are called:


(a) facultative anaerobes

(b) microaerophiles

(c) aerotolerant

(d) anoxygenic



12. Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called:


(a) facultative anaerobes

(b) microaerophiles

(c) aerotolerant

(d) anoxygenic


13. If you formed antibodies against O antigen of certain bacterial strains, where would the antibody be found to bind to the bacterial cell?


(a) nucleoid

(b) ribosome

(c) capsule

(d) outer membrane of cell wall



14. Which of the following components of various pathogenic microbes does not play a role in the attachment of pathogens to surfaces of the body?


(a) fimbrae

(b) flagella

(c) capsule

(d) glycocalax

(e) spike



15. The ______ are obligate intracellular parasites.


(a) Bacillus

(b) Chlamydia

(c) Clostridium

(d) Mycobacterium

(e) Mycoplasma



16. Which of the following constitutes the natural reservoir of Salmonella typhi?


(a) rats

(b) mosquitoes

(c) chickens

(d) dogs

(e) humans



17. For which of the following would penicillin therapy prove completely infective?


(a) Streptococcal sore throat

(b) gonorrhea

(c) gangrene (Clostridium perfringens)

(d) Mycoplasma pneumoniae

(e) Staphylococcal inpetigo



18. Toxic shock syndrome (TSS) is caused by:


(a) rare strains of Streptococcus pyogenes

(b) toxigenic strains of Straphylococcus aureus

(c) Clostridium botulinum

(d) Escherichia coli

(e) Clostridium perfringens




19. A major distinguishing characteristic of archael phospholipids is the presence of:


(a) ester linkages

(b) ether linkages

(c) hydrophobic fatty acids

(d) polar head groups

(e) sterols



20. Members of the genus Arthrobacter are:


(a) irregular branched rods in exponential growth.

(b) coccoid during stationary phase

(c) both a and b

(d) neither a nor b



21. The facultatively anaerobic gram-negative rods consist of the:


(a) Enterobacteriaceae

(b) Vibrionaceae

(c) Pasteurellaceae

(d) all of the above



22. Yersinia pestis is best known as the causative agent of:


(a) bubonic plague

(b) whooping cough

(c) cholera

(d) pneumonia



23. Which of the following bacterial pathogens is a gram-positive rod?


(a) Bordetella pertussis

(b) Neisseria gonorrhoeae

(c) Mycobacterium tuberculosis

(d) Haemophilus influenzae

(e) Shigella flexneri.



24. A genus of filamentous bacteria which has been extensively studied because of its antibiotic-producing potential is


(a) Actinoplanes

(b) Fusibacterium

(c) Mycobacterium

(d) Nocardia

(e) Streptomyces.



25. An organism that uses light energy, H2S as an electron donor, and CO2 as a sole carbon source is


(a) chemotrophic, lithotrophic and autotrophic

(b) chemotrophic, organotrophic and heterotrophic

    1. phototrophic and autotrophic
    2. phototrophic, lithotrophic and heterotrophic
    3. phototrophic, organotrophic and heterotrophic.



26. Preventive measures against staphylococcal food poisoning include.


(a) immunization

(b) introduction of antibiotics into foods

(c) proper covering and refrigeration of foods after preparation

(d) all of these (a, b and c)

(e) none of these (a, b or c) is appropriate for "staph" food poisoning.



27. Which of the following traits is characteristic of Staphylococcus aureus?


(a) gram-negative

(b) alpha-hemolysis on blood agar

(c) does not ferment mannitol

(d) coagulase positive

(e) occurs in chains.



28. Asexual spore production is characteristic of the


(a) Actinomyces

(b) Chlamydia

(c) mollicutes

(d) Rickettsia

(e) Streptomyces



29. Although placed within the Gram Positive group of Bacteria, Deinococcus is different because


(a) it has a unique phylogenetic position

(b) has an outer membrane

(c) is homofermentative

(d) both a and b.

(e) both a and c.



30. All Bacillus species are known as


(a) endospore formers

(b) obligate anaerobes

(c) obligate aerobes

(d) both a and b.

(e) both a and c.


31. Bacillus thuringiensis is important because


(a) it is considered a biological insecticide

(b) it can be used as an agent for biological warfare

(c) causes food poisoning in humans

(d) survives large doses of radiation

(e) ferments dairy foodstuffs.


32. Homofermentative lactic acid bacteria


(a) are aldolase positive

(b) are aldolase negative

    1. produce large amounts of CO2 and ethanol
    2. both a and c.
    3. both b and c.

(64 marks)