Category: MICROBIOLOGY Objective Questions

Microbiology Multiple Choice Questions on “Historical Highlights of Chemotherapy”.

1. Which of the following is not a characteristic of a chemotherapeutic agent?
A. low toxicity for host cells
B. high toxicity for the parasites
C. less penetrating power
D. does not affect the host’s natural defense mechanism
Answer: C
Clarification: A chemotherapeutic agent must be able to come in contact with the parasite by penetrating the cells and tissues of the host in effective concentrations.

2. Phenol is considered as a chemotherapeutic agent.
A. True
B. False
Answer: B
Clarification: Antiseptics and germicides such as phenol, coal-tar derivatives and many mercurial compounds are unsatisfactory as chemotherapeutic agents as they do not show selective toxicity for the parasite.

3. Which was the first disease for which a chemotherapeutic agent was used?
A. Syphilis
B. Malaria
C. Small pox
D. AIDS
Answer: A
Clarification: Syphilis is the first known disease for which a chemotherapeutic agent was used. An arsenical compound known as Salvarsan was synthesized by Paul Ehrlich in 1910 to treat this disease.

4. Sulfanilamide was synthesized by which of the following research scientists?
A. Eisenberg
B. Gelmo
C. Ehrlich
D. Domagk
Answer: B
Clarification: Domagk showed the therapeutic value of a group of compounds known as the sulfonamides and Sulfanilamide was the first compound in this group to be synthesized by Gelmo in 1910.

5. Sulfonamides and arsphenamine are similar in their specificity for a special group of organism.
A. True
B. False
Answer: B
Clarification: Sulfonamides are not specific for a special group of organisms, as arsphenamine is for Treponema, but are effective against a large variety of pathogenic organisms.

6. Which of the following chemothearpeutic agent is extensively used because of their antibacterial effectiveness in a wide range of bacterial infections?
A. arsphenamine
B. sulfanilamide
C. sulfonamide
D. sulfadiazine
Answer: D
Clarification: Sulfadiazine and sulfamerazine are extensively used because of their antibacterial effectiveness in a wide range of bacterial infections and because they are least likely to produce toxic reactions in the patient.

7. The antibiotic penicillin was discovered by which of the following researchers?
A. Emmerich and Low
B. Gratia and Dath
C. Alexander Flemming
D. Vuillemin
Answer: C
Clarification: Alexander Flemming identified the famous antibiotic penicillin obtained from the mold Penicillium sp.

8. Which of the following antibiotic is not involved in the inhibition of specific enzyme systems?
A. Penicillin
B. Tetracycline
C. Sulphonamides
D. Chloramphenicol
Answer: C
Clarification: The sulphonamides have their antibacterial attack directed towards a specific essential enzyme. Their structure is related to p-aminobenzoic acid (PABA. which is a precursor to their synthesis of the essential coenzyme tetrahydrofolic acid (THFA).

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Microbiology Multiple Choice Questions on “Industrial Uses of Bacteria”.

1. Which of the following microorganism produces dextran?
A. Bacillus polymyxa
B. Bacillus thuringiensis
C. Leuconostoc mesenteroides
D. Streptomyces olivaceus
Answer: C
Clarification: Leuconostoc mesenteroides is the producer organism for dextran which acts as a stabilizer in food products and as a blood plasma substitute.

2. Which of the following carbohydrates are mainly present in whey?
A. glucose
B. lactose
C. fructose
D. sucrose
Answer: B
Clarification: Whey represents a satisfactory medium for the growth of certain bacteria since it contains lactose, nitrogenous substances including vitamins, and salts.

3. Lactobacillus bulgaricus is a homofermentative organism.
A. True
B. False
Answer: A
Clarification: Lactobacillus bulgaricus grows rapidly and is homofermentative and thus is capable of converting the lactose to the single end product-lactic acid.

4. What temperature is necessary for the production of vinegar?
A. 43 degree C
B. 60 degree C
C. 10-13 degree C
D. 15-34 degree C
Answer: D
Clarification: For vinegar production it is necessary to keep the temperature between 15 and 34 degree C, the optimum for growth and metabolism of the acetobacters.

5. Which of the following product is used for the treatment of pernicious anemia?
A. Insulin
B. Streptokinase-streptodornase
C. Cobalamin
D. Sorbose
Answer: C
Clarification: Cobalamin or vitamin B12 is used for the treatment of pernicious anemia and also for food and feed supplements.

6. Microbial fermentation produces D optical isomers of the amino acids.
A. True
B. False
Answer: B
Clarification: The advantage of microbial fermentation processes is that the biologically active forms of the amino acids i.e. L optical isomers are produced.

7. Diaminopimelic acid (DAP) is produced by which of the following microorganism?
A. E.coli
B. Enterobacter aerogenes
C. Bacillus subtilis
D. Streptococcus equisimilis
Answer: A
Clarification: Production of lysine involves two stages among which the first stage is the formation of diaminopimelic acid (DAP) by E.coli.

8. Which of the following raw materials are important for the production of glutamic acid?
A. glycerol
B. corn-steep liquor
C. tryptone
D. biotin
Answer: D
Clarification: For glutamic acid the medium generally consists of carbohydrate, peptone, inorganic salts, and biotin; the concentration of biotin has a significant influence on the yield of glutamic acid.

9. Insulin was isolated from which of the following organs of animals?
A. small intestine
B. tongue
C. pancreas
D. stomach
Answer: C
Clarification: Commercial insulin for the therapy of diabetes was isolated from animal pancreatic tissue.

10. Which of the following yeast is used for the production of riboflavin?
A. Saccharomyces cerevisiae
B. Eremothecium ashbyi
C. Saccharomyces rouxii
D. Candida utilis
Answer: B
Clarification: Eremothecium ashbyi is used for the production of riboflavin which is used as a vitamin supplement.

11. Which of the following product utilizes whey as its raw material?
A. lactic acid
B. acetic acid
C. glutamic acid
D. lysine
Answer: A
Clarification: Whey is used for the production of lactic acid which can also be grown using other carbohydrate substances such as corn or potato starch.

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Microbiology Questions and Answers for Campus interviews focuses on “Diseases Caused by Clostridium, Corynebacterium and Mycobacterium”.

1. Which of the following organisms produces neurotoxin as a virulence factor?
A. Bacillus anthracis
B. Clostridium tetani
C. Streptococcus pneumoniae
D. Staphylococcus aureus
Answer: B
Clarification: Clostridium tetani produces only one virulence factor which is a powerful neurotoxin. It is the causative agent of tetanus.

2. Booster immunizations should be given every 10 years.
A. True
B. False
Answer: A
Clarification: Booster immunizations should be given every 10 years to maintain an adequate level of antitoxin to protect against tetanus.

3. Clostridium perfringens type A occurs as a natural flora of ______________
A. stomach
B. mouth
C. intestine
D. eyes
Answer: C
Clarification: Clostridium perfringens type A occurs as part of the normal flora of the human intestine.

4. __________________ is a hyaluronidase that may aid invasiveness of C.perfringens.
A. alpha toxin
B. theta toxin
C. µ toxin
D. √ toxin
Answer: C
Clarification: The µ toxin is a virulence factor produced by C.perfringens and is a hyaluronidase that may aid invasiveness.

5. What pressure of oxygen is used in the treatment involving the use of hyperbaric oxygen?
A. 1
B. 5
C. 100
D. 3
Answer: D
Clarification: In the treatment involving the use of hyperbaric oxygen, the patient is placed in a chamber containing 3 atmospheres pressure of pure oxygen several times a day for half-hour periods.

6. Which of the following temperature is suitable for the multiplication of clostridia spores?
A. 109 to116 degree F
B. 100 degree F
C. -2 to 16 degree F
D. 30-40 degree F
Answer: A
Clarification: If the meat or poultry is cooked at a temperature that does not kill the spores and is subsequently kept at a temperature of 109 to 116 degree F for atleast 2 hours, the clostridia may multiply.

7. Which serovar of C. botulinum occurs mainly in the sediments of the Great Lakes?
A. A
B. B
C. E
D. F
Answer: C
Clarification: Serovar E occurs mainly in the sediments of Great Lakes and along the coasts of western North America and northern Japan.

8. Patients with botulism are treated with monovalent antitoxin.
A. True
B. False
Answer: B
Clarification: Patients with botulism are treated with polyvalent antitoxin (i.e., antitoxin against toxin types A, B, and E) to neutralize any toxin that has not yet become fixed to nerve tissue.

9. Toxin A involved in pseudomembranous colitis is a type of _______________
A. endotoxin
B. enterotoxin
C. cytotoxin
D. neurotoxin
Answer: B
Clarification: Toxin A is an enterotoxin which causes fluid accumulation in the bowel. It is a type of exotoxin and is involved in pseudomembranous colitis.

10. Which of the following inactivates IgA antibodies?
A. Cord factor
B. Diphthin
C. Neuroaminidase
D. K antigens
Answer: B
Clarification: Diphthin is a protease which inactivates IgA antibodies. It is a virulence factor produced by C.diphtheriae.

11. Erythrasma is caused by which of the following microorganism?
A. Corynebacterium diphtheriae
B. Corynebacterium ulcerans
C. Corynebacterium minutissimum
D. Listeria monocytogenes
Answer: C
Clarification: Corynebacterium minutissimum is a species which causes a skin disease called erythrasma.

12. Schick Test is used for detection of which of the following disease?
A. Diphtheria
B. Tuberculosis
C. Erythrasma
D. Botulism
Answer: A
Clarification: The detection of persons susceptible to diphtheria by means of the Schick test has made the disease rare in the US. It is performed by infection of a very small amount of diphtheria toxin into the skin.

13. Which among the following species causes tuberculosis?
A. Mycobacterium leprae
B. Mycobacterium kansasii
C. Mycobacterium bovis
D. Mycobacterium ulcerans
Answer: C
Clarification: M.bovis and M. tuberculosis are pathogenic species and both cause tuberculosis. They regularly exhibit susceptibility to antituberculosis drugs.

To practice all areas of Microbiology for Campus Interviews, .

Microbiology Multiple Choice Questions on “Growth Cycle of Bacteria”.

1. The portion of the growth curve where rapid growth of bacteria is observed is known as ____________
A. Lag phase
B. Logarithmic phase
C. Stationary phase
D. Decline phase
Answer: B
Clarification: A typical growth curve has four regions. An initial period of no growth known as the lag phase, followed by rapid growth known as logarithmic phase. No growth is observed in the stationary phase and death phase.

2. The growth of bacterial population follows a geometric progression.
A. True
B. False
Answer: A
Clarification: The bacteria show growth by following binary fission as means of reproduction. Thus, if we start with a single bacterium, the increase in population is by geometric progression.

3. In the growth equation: n = 3.3 (log10 N – log10 No), n stands for ____________
A. total population
B. initial population
C. number of generations
D. growth constant
Answer: C
Clarification: In the above formula, n stands for the number of generations that have taken place after the growth.

4. Lag phase is also known as ___________
A. period of initial adjustment
B. transitional period
C. generation time
D. period of rapid growth
Answer: A
Clarification: In the lag phase, the bacteria maybe deficient in enzymes or coenzymes which must first be synthesized and thus time is required for adjustments in the physical environment. So it is also known as a period of initial adjustment.

5. The generation time for E.coli is ________
A. 20 minutes
B. 35 minutes
C. 2 minutes
D. 13 minutes
Answer: A
Clarification: The generation time for E.coli at a temperature of 37 degrees Celsius lies in the range of 15-20 minutes generally.

6. During exponential phase, growth rate is _______
A. same as generation time
B. reciprocal of generation time
C. time required for population to double
D. rate of doubling population
Answer: B
Clarification: During exponential growth, the growth rate (R) i.e., the number of generations per hour, is the reciprocal of the generation time g. Growth rate is the slope of the straight line obtained when the log number of cells is plotted against time.

7. In which of the following phase secondary metabolites are produced during growth?
A. Lag phase
B. Log/Exponential phase
C. Stationary phase
D. Death phase
Answer: C
Clarification: During the stationary phase, there is complete utilization of the nutrients present in media and thus produce secondary metabolites which are then used in different industries.

8. Which phase shows the reproduction rate equal to the equivalent death rate?
A. Log phase
B. Stationary phase
C. Death phase
D. Lag phase
Answer: B
Clarification: In the stationary phase there is a complete cessation of division and thus the reproduction rate is balanced by an equivalent death rate.

9. Which of the following is used to grow bacterial culture continuously?
A. Chemostat
B. Hemostat
C. Coulter-Counter
D. Turbidostat
Answer: A
Clarification: Chemostat is used for continuous cultivation. This system depends on the fact that the concentration of an essential nutrient within the culture vessel will control the growth rate of the cells.

10. The average size of the cells in the exponential phase is ___________
A. larger than the initial size
B. smaller than the initial size
C. equal to the initial size
D. maybe smaller or larger than the initial size
Answer: B
Clarification: During the exponential phase, the cells divide steadily at a constant rate and thus give a straight line. So the average size of cells goes on decreasing than the initial size due to binary fission.

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Microbiology Multiple Choice Questions on “World of Bacteria I – Facultatively Anaerobic Gram – Negative Rods”.

1. The cell diameter of bacteria belonging to family Enterobacteriaceae is ____________
A. 1 m
B. 1 cm
C. .3-1.5 micrometre
D. 5 micrometer
Answer: C
Clarification: A distinctive feature of the family Enterobacteriaceae is that the cell diameter is 0.3 to 1.5 micrometers.

2. What is the cell shape of the organisms belonging to the family Enterobacteriaceae?
A. vibrio
B. coccus
C. bacillus
D. straight rod
Answer: D
Clarification: The cell shape of organisms belonging to the family Enterobacteriaceae is that of a straight rod.

3. Enterobacteriaceae possesses endoflagella.
A. True
B. False
Answer: B
Clarification: Enterobacteriaceae possesses lateral flagella and moves by means of it. It does not possess endoflagella.

4. Which of the following genus of bacteria causes gastroenteritis in humans?
A. Salmonella
B. Enterobacter
C. Escherichia
D. Shigella
Answer: C
Clarification: Some bacteria of genus Escherichia causes gastroenteritis and some others can also cause urinary tract infections.

5. Enterobacter sp. gives negative result for Voges-Proskauer test.
A. True
B. False
Answer: B
Clarification: Enterobacter sp. gives positive results for Voges-Proskauer test by giving a reddish-pink colouration.

6. Which of the following genus of bacteria under the family Enterobacteriaceae is mainly associated with plants?
A. Erwinia
B. Serratia
C. Proteus
D. Yersinia
Answer: A
Clarification: Bacteria belonging to the genus Erwinia differ from most other Enterobacteriaceae by being mainly associated with plants. They are often plant pathogens, causing diseases such as blights, leaf spot, wilts, etc.

7. Which of the following is the causative agent of the plague?
A. Y.enterocolitica
B. Y.pestis
C. P.mirabilis
D. E.coli
Answer: B
Clarification: Yersiniae are parasites of animals but can also cause infections in humans. For example, Y.pestis is the causative agent of the plague.

8. The family Vibrionaceae is _________________
A. oxidase-positive
B. oxidase-negative
C. coccus shaped
D. non-motile
Answer: A
Clarification: A distinctive feature of the family Vibrionaceae is that they are usually oxidase-positive. They are motile by means of polar flagella and cell shape is that of curved or straight rods.

9. Which of the following genus shows the characteristic of bioluminescence?
A. Aeromonas
B. Zymomonas
C. Vibrio
D. Haemophilus
Answer: C
Clarification: Some species of genus Vibrio can emit light of a blue-green color(bioluminescence), an oxygen-dependent reaction catalyzed by the enzyme luciferase.

10. Among the given families, which family contains organisms that are non-motile?
A. Enterobacteriaceae
B. Vibrionaceae
C. Pseudomonadaceae
D. Pasteurellaceae
Answer: D
Clarification: Pasteurellaceae contains cells that are nonmotile. Their cell diameter is very small and the shape is that of a straight rod.

11. The X factor and/or the V factor is required by which genus of bacteria?
A. Pasteurella
B. Haemophilus
C. Actinobacillus
D. Zymomonas
Answer: B
Clarification: Haemophilus bacteria is distinguished by unusual nutritional requirements: the X factor (heme, occurring in blooD. and/or the V factor(the coenzyme nicotinamide adenine dinucleotide).

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Microbiology Multiple Choice Questions on “Morphology of Protozoa”.

1. Leishmania donovani measures _____________ in length.
A. 600 micrometre
B. 1 to 4 micrometre
C. 2 mm
D. 2000 micrometre
Answer: B
Clarification: Leishmania donovani, the cause of human disease kala azar, measures 1 to 4 micrometre in length.

2. Protozoan mobility is due to the fibrils present.
A. True
B. False
Answer: B
Clarification: Protozoan contractility is probably due to the fibrils. Submicroscopic protein fibrils are groups of parallel fibrils in the cytoplasm.

3. Plasmagel is known as __________________
A. cytoplasm
B. endoplasm
C. ectoplasm
D. myonemes
Answer: C
Clarification: Plasmagel is known as the ectoplasm. The cytoplasm is differentiated into endoplasm and ectoplasm. The ectoplasm is more gel-like and the endoplasm is more voluminous and fluid.

4. Golgi bodies are also known as __________________
A. dictyosomes
B. kinetosomes
C. blepharoplasts
D. myonemes
Answer: A
Clarification: Golgi complexes are also known as dictyosomes which means piles of membranous sacs.

5. The micronucleus in protozoa is concerned with reproductive activity.
A. True
B. False
Answer: A
Clarification: The micronucleus is concerned with reproductive ability whereas the macronucleus controls the metabolic activities and regeneration processes.

6. How many haploid chromosomes are present in Spirotrichonympha polygyra?
A. 60
B. 7
C. 2
D. 40
Answer: C
Clarification: It has been shown that number of chromosomes is constant for a particular species of protozoan. Spirotrichonympha polygyra has 2 haploid chromosomes.

7. Amoeba proteus have a diffuse layer of which of the following over the plasmalemma?
A. glucose
B. chitin
C. cellulose
D. mucopolysaccharides
Answer: D
Clarification: Amoeba proteus have a diffuse layer of mucopolysaccharides over the plasmalemma. This layer is thought to play an important role in pinocytosis or in adhesion of the cell to the substratum.

8. Among the following which layer is directly apposed to the cell surface?
A. tests
B. theca
C. shells
D. loricae
Answer: B
Clarification: The theca is a secreted layer directly apposed to the cell surface. Tests, shells, and lorica are coverings that are loosely apposed to the cell surface. Tests, shells, and lorica are coverings that are loose-fitting.

9. Which of the following is the actual opening in ciliates through which food is ingested?
A. cytosome
B. oral groove
C. peristome
D. cytopharynx
Answer: A
Clarification: In ciliates the cytosome is the actual opening through which food is ingested. It ranges from a simple round opening to a slitlike structure surrounded by feeding membranelles.

10. Which of the following protective structures occur in the tentacles of suctorian protozoa?
A. mucocysts
B. trichocysts
C. toxicysts
D. haptocysts
Answer: D
Clarification: Haptocysts occur in the tentacles of suctorian protozoa and are used to contact and immobilize prey.

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