Category: MICROBIOLOGY Objective Questions

Microbiology Multiple Choice Questions on “Microorganisms and Industry”.

1. Which of the following is not a desired characteristic of the organism to be used for industrial application?
A. should produce less amount of product
B. should be readily available
C. should grow rapidly
D. should be nonpathogenic
Answer: A
Clarification: The organism to be used must be able to produce appreciable amount of the product. It should be readily available and should grow rapidly and vigorously. It should be nonpathogenic.

2. Industrial fermentation are performed in large tanks of capacity ______________
A. 100 gal
B. 1000 gal
C. 50,000 gal
D. 10,000 gal
Answer: C
Clarification: Industrial fermentation are performed in large tanks; capacities of 50,000 gal are not unusual.

3. Solvents and enzymes are found in which of the following categories of microbial products?
A. Pharmaceutical chemicals
B. Commercially valuable chemicals
C. Food supplements
D. Alcoholic beverages
Answer: B
Clarification: Solvents, enzymes, and intermediate compounds for the synthesis of other substances are representative of the kinds of substances produced commercially by microorganisms.

4. Which of the following enzymes cut the DNA molecule at a particular nucleotide sequence?
A. restriction endonuclease
B. exonuclease
C. ligase
D. polymerase
Answer: A
Clarification: Restriction endonuclease cut double-stranded DNA molecules at particular nucleotide sequences and thus produce a well-defined DNA fragment for a given enzyme and a given DNA.

5. Eco R1 cuts the plasmid DNA and the donor DNA such that both the ends are same.
A. True
B. False
Answer: B
Clarification: The endonuclease Eco R1 cuts the plasmid DNA and the donor DNA in a manner such that the ends of each are identical and self-complementary.

6. Which of the following product is used for the treatment of blood clots?
A. insulin
B. interferon
C. urokinase
D. somatostatin
Answer: C
Clarification: The pharmaceutical industry has already produced several products for human therapy by the help of genetic engineering such as urokinase that is used for the treatment of blood clots; human insulin and interferons.

7. VP3 protein is isolated from which of the following viruses?
A. TMV
B. HIV
C. HRV
D. FMDV
Answer: D
Clarification: VP3 is the protein from the shell of the foot-and-mouth disease virus (FMDV), which can act as a vaccine for immunizing livestock against foot-and-mouth disease.

8. Transfection involves the introduction of plasmid hybrid DNA into the host cell.
A. True
B. False
Answer: B
Clarification: Transfection involves the introduction of phage hybrid DNA into the host cell whereas transformation involves the introduction of plasmid hybrid DNA into a competent host bacterial cell.

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Microbiology Questions and Answers for Entrance exams focuses on “Diseases Caused by Staphylococcus, Streptococcus and Bacillus”.

1. Which of the following toxins cause damage to the tissue cells by its phospholipase action?
A. alpha toxin
B. delta toxin
C. protein A
D. coagulase
Answer: B
Clarification: Delta toxin damages tissue cells by its action as a phospholipase. It is produced by human strains of S. aureus.

2. Which of the following microorganism causes lesions in the form of abscesses?
A. Staphylococcus aureus
B. Streptococcus pyogenes
C. Streptococcus pneumoniae
D. Clostridium perfringens
Answer: A
Clarification: Staphylococcus aureus causes localized infections in which the characteristic lesion is a walled-off fort called the abscess— a cavity filled with pus cells (neutrophils), dead tissue, and bacteria.

3. Antibiotics can easily reach the staphylococci.
A. True
B. False
Answer: B
Clarification: Antibiotics have difficulty in reaching the staphylococci and may have to be administered to a patient for a long period in order to be effective.

4. Streptococus pyogenes comprises which Lancefield group?
A. A
B. B
C. C
D. D
Answer: A
Clarification: Streptococus pyogenes comprises Lancefield group A. This organism causes several diseases like sore throat, scarlet fever etc.

5. Which of the following microbe does not belong to Group D enterococci group?
A. S. faecalis
B. S. faecium
C. S. durans
D. S. bovis
Answer: D
Clarification: S. bovis belongs to Group D nonenterococci group. All other above microbes belong to Group D enterococci group.

6. Scarlet fever is similar to the pharyngitis in all respects.
A. True
B. False
Answer: B
Clarification: Scarlet fever is similar to the pharyngitis except for the skin rash that appears because of the erythrogenic toxin.

7. Which of the following immunity is protective against infection by S.pyogenes?
A. cell-mediated immunity
B. antigen-antibody immunity
C. humoral immunity
D. no cure present
Answer: C
Clarification: The only type of immunity that is protective against infection by S. pyogenes is humoral immunity: antibodies against M proteins act as opsonins, enhancing phagocytosis of the streptococci.

8. Puerperal fever is a streptococcal infection of the ______________
A. kidney
B. skin
C. uterus
D. heart
Answer: C
Clarification: Puerperal fever, sometimes called puerperal sepsis, is a streptococcal infection of the uterus of a mother and is acquired at childbirth.

9. Which of the following is a major virulence factor of Streptococcus pneumoniae?
A. polysaccharide capsule
B. M protein
C. streptolysin O
D. streptolysin S
Answer: A
Clarification: The major virulence factor is the polysaccharide capsule, which effectively inhibits phagocytosis.

10. Which drug is used for the treatment of anthrax?
A. erythromycin
B. penicillin
C. tetracycline
D. ampicillin
Answer: B
Clarification: Penicillin is the drug of choice for the treatment of anthrax. A live attenuated vaccine is available for prevention of anthrax in cattle and sheep.

To practice all areas of Microbiology for Entrance exams, .

Microbiology Multiple Choice Questions on “Reproduction – Modes of Cell Division”.

1. Growth of bacteria or microorganisms refer to __________________
A. an increase in the size of an individual organism
B. an increase in the mass of an individual organism
C. changes in the total population
D. an increase in number of cells
Answer: D
Clarification: Growth denotes the increase in number of cells beyond that present in the original inoculum. It does not refer to an increase in size or mass of an individual organism.

2. Transverse binary fission requires the formation of a crosswall.
A. True
B. False
Answer: A
Clarification: The most important mode of cell division in the usual growth of bacterial population is transverse binary fission, in which a single cell divides after developing a transverse septum(crosswall).

3. Which of the following bacterial species divides by fragmentation?
A. Bacillus subtilis
B. Streptococcus faecalis
C. Rhodopseudomonas acidophila
D. Nocardia sp.
Answer: D
Clarification: Bacteria that produce extensive filamentous growth, such as Nocardia sp. reproduce by fragmentation of the filaments into small bacillary or coccoid cells, each of which gives rise to new growth.

4. Rhodopseudomonas acidophila reproduces by which of the following methods?
A. Binary fission
B. Budding
C. Fragmentation
D. Sporulation
Answer: B
Clarification: Rhodopseudomonas acidophila reproduces by budding, a process in which a small protuberance(buD. develops at one end of the cell; this enlarges and eventually develops into a new cell which separates from the parent.

5. Streptomyces sp. show the budding mode of reproduction.
A. True
B. False
Answer: B
Clarification: Streptomyces sp. produce many spores per organism by developing crosswalls(septation) at the hyphen tips and then each spore gives rise to a new organism.

6. The synthesis of new membrane material during reproduction in Gram-positive cells is performed by which of the following organelles?
A. Nucleus
B. Mesosome
C. Endoplasmic Reticulum
D. Cytoplasmic membrane
Answer: B
Clarification: The first step in reproduction is an inward growth of the cytoplasmic membrane at the middle of the cell. A mesosome which is usually attached to the cytoplasmic membrane in Gram-positive cells have a role in the synthesis of new membrane material.

7. Equatorial ridge formation in the cell wall takes place in which of the following bacteria?
A. Streptomyces sp.
B. Bacillus subtilis
C. Streptococcus faecalis
D. Escherichia coli
Answer: C
Clarification: In Streptococcus faecalis, all of the new wall material formed by the dividing cell is made during synthesis of the septum which begins beneath an equatorial ridge in the cell wall.

8. When septum formation occurs near the pole of cell then it results in the formation of daughter cell known as _________
A. microcell
B. macrocell
C. minicell
D. daughter cell
Answer: C
Clarification: In some mutants of E.coli and B.subtilis, septum forms near the pole resulting in a very small daughter cell termed as minicell which lacks DNA and therefore cannot multiply.

9. A bleb or fold like formation occurs in which of the following bacteria?
A. Rhodopseudomonas acidophila
B. Bacillus subtilis
C. E.coli
D. Streptococcus faecalis
Answer: C
Clarification: In E.coli a bleb or fold of the outer membrane occurs at the site where the septum will be formed; it is not evident in the final stages of septum formation. The cytoplasmic membrane and the peptidoglycan layer grow inward in the early stages but the cytoplasmic membrane does not invaginate until the final stages of septum formation.

10. Which of the following does not occur during binary fission in bacteria?
A. Cell elongation
B. Cytokinesis
C. DNA duplication
D. Spindle formation
Answer:d
Clarification: Binary fission is a form of asexual reproduction that starts with cell elongation followed by division of cytoplasm(cytokinesis) and nucleus and finally DNA duplication occurs resulting in the formation of two daughter cells.

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Microbiology Multiple Choice Questions on “World of Bacteria I – Aerobic Gram – Negative Rods and Cocci”.

1. Pseudomonas bacteria uses which of the following as an electron acceptor for anaerobic respiration?
A. Oxygen
B. Nitrate
C. Phosphate
D. Sulphate
Answer: B
Clarification: All pseudomonads can grow aerobically, but some can also grow anaerobically by using nitrate as an electron acceptor.

2. Pseudomonas maltophilia is a fluorescent species.
A. True
B. Flase
Answer: B
Clarification: Pseudomonas maltophilia is a non-fluorescent species that is also frequently isolated from clinical specimens.

3. Pyocyanin, a blue water-soluble pigment is produced by which of the following pseudomonads?
A. P.mallei
B. P.syringae
C. P.fluorescens
D. P.aeruginosa
Answer: D
Clarification: Pseudomonas aeruginosa produces a water-soluble blue pigment, pyocyanin. The organism is mainly a soil and water saprophyte but can also be isolated from wound, burn etc.

4. Which of the following are important plant pathogens?
A. P. aeruginosa
B. P.maltophilia
C. P.syringae
D. P.pseudomallei
Answer: C
Clarification: P. syringae are important plant pathogens, causing diseases such as leaf spot, leaf stripe, wilt, and necrosis.

5. What is the color of the pigment xanthomonadin?
A. Blue
B. Yellow
C. Fluorescent
D. Red
Answer: B
Clarification: Xanthomonadin is a yellow pigment formed by bacteria of the genus Xanthomonas of the family Pseudomonadaceae.

6. Which of the following is an important characteristic of bacteria belonging to Zoogloea?
A. They are plant pathogens
B. Cells are embedded in a gelatinous matrix
C. Cause diseases in humans
D. Useful for industrial applications
Answer: B
Clarification: The outstanding characteristic of the genus Zoogloea is the embedment of cells in a gelatinous matrix to form slimy masses with a fingerlike morphology. They are mainly used in the sewage treatment plant.

7. Which of the following family of bacteria fix nitrogen under aerobic conditions?
A. Pseudomonadaceae
B. Azotobacteraceae
C. Rhizobiaceae
D. Methylcoccaceae
Answer: B
Clarification: The family Azotobacteraceae have organisms that can fix nitrogen under aerobic conditions.

8. Agrobacterium also fixes atmospheric nitrogen.
A. True
B. False
Answer: B
Clarification: Agrobacteria do not fix atmospheric nitrogen. The organisms are plant pathogens that incite tumors when they invade roots, crown and stems.

9. Methylococcus and Methylomonas are all _______________ methane-oxidizers.
A. aerobic
B. facultative
C. obligate
D. anaerobic
Answer: C
Clarification: Methylococcus and Methylomonas are all obligate methane-oxidizers i.e., carbon-sources such as glucose cannot be used for growth.

10. Which of the following have peritrichous flagella?
A. Acetobacter
B. Gluconobacter
C. Agrobacteria
D. Rhizobium
Answer: A
Clarification: Acetobacter possesses peritrichous flagella. They belong to the family Acetobacteraceae.

11. Bacteria belonging to the genus Legionella contains which of the following amino acid?
A. Lysine
B. Arginine
C. Glycine
D. Cysteine
Answer: D
Clarification: Bacteria belonging to genus Legionella are rod-shaped bacteria that require L-cysteine, iron saltsand activated powdered charcoal for growth.

12. Which of the following organism causes whooping cough in humans?
A. E.coli
B. Bordetella pertussis
C. Francisella tularensis
D. F.meningosepticum
Answer: B
Clarification: Bordetella pertussis occurs only in humans and causes whooping cough. They are parasitic and pathogenic for various mammalian hosts.

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Microbiology Multiple Choice Questions on “Ecology and Importance of Protozoa”.

1. pH range optimal for maximum metabolic activity of protozoa is ______________
A. 2-3
B. 12-14
C. 6-8
D. 4-6
Answer: C
Clarification: For the majority of pH range of 6.0 to 8.0 is optimal for maximum metabolic activity. Some protozoa can tolerate a wide range of pH, for example, pH 3.2 to 8.7.

2. Protozoa that eat other organisms are known as _______________
A. saprophytic
B. holozoic
C. parasitic
D. mutualistic
Answer: B
Clarification: Holozoic protozoa are protozoa that eat other organisms. Species of Paramecium are holozoic and they must have a supply of bacteria or other protozoa.

3. What is the maximum temperature for protozoa?
A. 40 degrees C
B. 10 degrees C
C. 16 degrees C
D. 25 degrees C
Answer: A
Clarification: Most protozoa have an optimum temperature of between 16 and 25 degree C; the maximum temperature is between 36 and 40 degree C.

4. The process in which protozoa attaches themselves to a host’s body is known as __________________
A. Endocommensalism
B. Ectocommensalism
C. Parasitic
D. Mutualism
Answer: B
Clarification: Ectocommensalism is often represented by protozoa which attach themselves to a host’s body. In commensalism the host is neither injured nor benefitted, but the commensal is benefitted.

5. Certain flagellates of protozoa are present in the gut of some termites in a mutualistic relationship.
A. True
B. False
Answer: A
Clarification: Certain flagellates are present in the gut of termites and digest the woody material eaten by the termite to a glycogenous substance which can be used by the host cells. If deprived of these flagellates, the termite dies.

6. African sleeping sickness is caused by _________________
A. bacteria
B. fungi
C. protozoa
D. viruses
Answer: C
Clarification: Some protozoa causes diseases in animals, including humans. Some well-known protozoan diseases in humans are intestinal amoebiasis, African sleeping sickness, and malaria.

7. Which of the following is not a function of protozoa?
A. acts as a link in the food chain
B. used in manufacture of food products
C. decomposition process
D. to study cell cycles
Answer: B
Clarification: Protozoa serve as an important link in the food chain of communities in aquatic environments. They also make use of the substances produced and organisms involved in the final decomposition stage of organic matter. Some species of protozoa have been used to study cell cycles and nucleic acid biosynthesis during cell division.

8. Which of the following is an aerobic protozoa?
A. Metopus
B. Saprodinium
C. Epalxis
D. Vorticella
Answer: D
Clarification: Vorticella is an aerobic protozoa involved in the aeration and flocculation steps of sewage treatment. Others are all anaerobic protozoa.

9. Red snow of high altitudes is due to the presence of ________________
A. bacteria
B. protozoa
C. algae
D. fungi
Answer: B
Clarification: The red snow of high altitudes is due to the presence of several hematochrome-bearing flagellates or protozoa which are considered as algae by some biologists.

10. When parasitic protozoa parasitize other protozoan it is known as ______________
A. Parasitism
B. Mutualism
C. Hyperparasitism
D. Hypoparasitism
Answer: C
Clarification: Some parasitic protozoa parasitize other protozoan or metazoan parasities. Such an association is termed hyperparasitism.

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