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Interview MCQ Set 1

1. Which of the following is a characteristic of beef extract?
a) product resulting from the digestion of proteinaceous materials
b) aqueous extract of lean beef tissue
c) aqueous extract of yeast cells
d) complex carbohydrate obtained from certain marine algae

View Answer

Answer: b [Reason:] Beef extract, a complex raw material used as ingredient for preparing bacteriological media is an aqueous extract of lean beef tissue concentrated to a paste.

2. Which of the following is used as a solidifying agent for media?
a) Beef extract
b) Peptone
c) Agar
d) Yeast extract

View Answer

Answer: c [Reason:] Agar is used as a solidification agent for media and is not considered a source of nutrient to the bacteria. Agar dissolved in aqueous solutions, gels when the temperature is reduced below 45 degree Celsius.

3. Which of the following is a rich source of B vitamins?
a) Peptone
b) Yeast extract
c) Beef extract
d) Agar

View Answer

Answer: b [Reason:] Yeast extract which is an aqueous extract of yeast cells is a very rich source of the B vitamins and it also contains apart from it organic nitrogen and carbon compounds.

4. The isolation of gonorrhea-causing organism, Neisseria gonorrhoeae by the use of certain antibiotics in media is an example of which of the following?
a) Selective media
b) Differential media
c) Enriched media
d) Assay media

View Answer

Answer: a [Reason:] The isolation of gonorrhea-causing organism,Neisseria gonorrhoeae, from a clinical specimen is facilitated by the use of media containing certain antibiotics; these antibiotics do not affect N.gonorrhoeae but do inhibit the growth of contaminating bacteria. This is an example of selective media as it allows the growth of only a particular microorganism.

5. Nutrient broth, a liquid media contains beef extract and peptone respectively in how much amounts?
a) 0.2%, 0.4%
b) 0.1%, 0.6%
c) 0.3%, 0.5%
d) 0.7%, 0.3%

View Answer

Answer: c [Reason:] Nutrient broth which is the most widely used media in general bacteriological work, contains 0.3 percent beef extract and 0.5 percent peptone.It may also contain if required 0.8 percent NaCl to maintain the salt concentration.

6. Which of the following instrument is used for sterilizing the media after it has been prepared?
a) Autoclave
b) Laminar Air Flow Chamber
c) Inoculum Needle
d) Incubator

View Answer

Answer: a [Reason:] Autoclave is a type of pressure cooker which has steam at 121.5 degree Celsius and under 15 psi pressure. This steam kills all the microbes present in the media and sterilizes it.

7. Colony formation can be observed in liquid media broth.
a)True
b) False

View Answer

Answer: b [Reason:] If microbial growth is found in liquid media, then the media shows turbidity but no colony formation can be observed. But in solid media microbial growth can be observed by colony formation as the media is already turbid due to the presence of agar powder.

8. Which of the following is a Complex media for fungal growth?
a) Nutrient broth
b) Luria-Bertani media
c) Potato Dextrose Agar(PDA) media
d) Mac Conkey Agar media

View Answer

Answer: c [Reason:] Complex media is a chemically undefined media where the exact composition is not known. For fungal growth, complex media used is Potato Dextrose Agar(PDA) media.

9. Which of the following are functions of Maintenance Media?
a) used for assay of vitamins,amino acids
b) used for determining the bacterial content
c) used for determining the type of growth produced by bacteria
d) used for the maintenance of the viability and physiological characteristics

View Answer

Answer: d [Reason:] Satisfactory maintenance of the viability and physiological characteristics of culture over time may require a medium different from that which is optimum for growth.Prolific, rapid growth may also be associated with rapid death of the cells at the end of the growth phase. Thus, a maintenance medium is required then.

10. Which of the following bacteria requires nicotinic acid as a growth factor in their media?
a) Proteus vulgaris
b) Nitrosomonas sp.
c) E. coli
d) Leuconostoc mesenteroides

View Answer

Answer: a [Reason:] Proteus vulgaris require nicotinic acid as a growth factor in their media along with glucose as a carbon source and also Ammonium Chloride.

Interview MCQ Set 2

1. Alginic acid is obtained from ______________
a) brown algae
b) red algae
c) yello-green algae
d) golden algae

View Answer

Answer: a [Reason:] Alginic acid and its salts are obtained from the walls of brown algae, where they may represent as much as 25 percent of the dry weight.Laminaria,Fucus are some of the species producing this compound.

2. Agar is obtained from the algal species of _______________
a) Chondrus
b) Gigartina
c) Gelidium
d) Laminaria

View Answer

Answer: c [Reason:] Species of Gelidium and Gracilaria belonging to red algae are extensively used for obtaining agar.

3. Carrageenan is used as a ______________
a) emulsifier
b) solidifying agent
c) binder
d) emulsifier and binder

View Answer

Answer: d [Reason:] Carrageenan has been used as a stabilizer or emulsifier in foods such as ice-cream and other milk products.It is also used as a binder in toothpaste or in pharmaceutical products, as well as an agent in ulcer therapy.

4. The famous Japanese dish sushi is made with the help of the red algae named ____________
a) Nemalion
b) Porphyra
c) Chondrus
d) Eucheuma

View Answer

Answer: b [Reason:] Porphyra is used as a food in Japan, where it is called “nori” and is usually processed into dried sheets.Nori is commonly toasted over a flame and sprinkled in soup or rice, or it is rolled around flavoured rice with fish or vegetables to make sushi.

5. Which among the following is a pathogenic algae for humans?
a) Prototheca
b) Chlorella
c) Cephaleuros
d) Acanthopeltis

View Answer

Answer:a [Reason:] Prototheca has been found to be a probable pathogen of humans.It has been found in systemic and subcutaneous infections, as well as in bursitis.

6. Algae are known as primary producers.
a) True
b) False

View Answer

Answer: a [Reason:] Algae form the base or beginning of most aquatic food chains because of their photosynthetic activities and are therefore called primary producers of organic matter.

7. Agar and carrageenan are polymers of _________________
a) glucose
b) phosphoric acid
c) starch
d) galactose

View Answer

Answer: d [Reason:] Agar and carrageenan are polymers of galactose, or galactose-containing compounds, with sulfated groups.Agar and carrageenan are both called sulfated galactans.

8. Which of the following species are imporant for cervical dilation?
a) Laminaria japonica
b) Gracilaria
c) Chondrus
d) Gonyaulax catenella

View Answer

Answer: a [Reason:] The stipe of the brown alga Laminaria japonica may be used by the physicians for cervical dilation and/or softening of the cervix (for example, in performing an abortion or placing a radium implant).

9. Which of the following algae continue to be a significant food in China?
a) brown algae
b) green algae
c) red algae
d) yellow algae

View Answer

Answer: c [Reason:] Red algae continue to be a significant food in China.Such algae have been a food staple and delicacy for the Chinese for thousands of years.

10. Which of the following species produces neurotoxin which causes death of aquatic animals?
a) Chlorella
b) Gonyaulax
c) Prototheca
d) Cephaleuros

View Answer

Answer: b [Reason:] It is known that certain dinoflagellates belonging to the genera Gymnodinium and Gonyaulax cause death of aquatic animals by producing a high molecular weight neurotoxin.

Interview MCQ Set 3

1. In DNA molecule, the amount of purines is equal to the amount of pyrimidines.
a) True
b) False

View Answer

Answer: a [Reason:] In DNA the nitrogenous bases like adenine binds with thymine, and guanine binds with cytosine.As a consequence, the ratio of adenine to thymine or of guanine to cytosine in double stranded DNA is always 1:1.So the amount of purines is equal to the amount of pyrimidines.

2. RNA consists of which combination of bases?
a) Thymine,Guanine,Cytosine
b) Guanine,Cytosine,Uracil
c) Thymine,Adenine,Guanine
d) Adenine,Cytosine,Thymine

View Answer

Answer: b [Reason:] RNA is composed of nitrogenous bases adenine,guanine,cytosine and uracil. They do not contain thymine as present in DNA.

3. Which of the following are features of semiconservative replication?
a) RNA replicates DNA molecule
b) The DNA molecule produced contains two old templates
c) One new DNA helix is formed
d) DNA duplicates itself and the new chain contains old template strand and new complementary strand

View Answer

Answer: d [Reason:] In semiconservative replication DNA duplication occurs in which one polynucleotide chain acts as a template to direct the synthesis of a new chain complementary to itself.It results two daughter helices, each containing one old template strand and one new complementary strand.

4. The chromosome of a typical bacterium is ________________
a) circular double-stranded DNA
b) circular single-stranded DNA
c) double-helix DNA
d) single stranded DNA

View Answer

Answer: a [Reason:] The chromosome of a typical bacterium is a circular double-stranded DNA molecule; that is, the double helix for a complete genome has no free ends.

5. If the chromosome were extended linearly then it would approximately measure?
a) 13500 micrometre
b) 1000 micrometre
c) 1250 micrometre
d) 500 micrometre

View Answer

Answer: c [Reason:] If the chromosome were extended linearly then it would measure approximately 1250 micrometers or 1.25 mm which is several hundred times longer than the bacterial cell that contains it.

6. The Lambda Bacteriophage carries out which of the following replication methods?
a) Theta mode
b) Sigma mode
c) Linear mode
d) Does not carry out replication

View Answer

Answer: b [Reason:] The Lambda Bacteriophage follows sigma mode of replication in which the intermediate structures of DNA have sigma conformation.In this replication begins with the cleavage of a phosphodiester bond in one strand of the circular DNA molecule to produce a nick with 3’-OH and 5’-PO4 ends on that strand.

7. Which of the following replication methods leads to the production of two circular daughter chromosomes?
a) Theta mode
b) Sigma mode
c) Linear mode
d) Rolling circle method

View Answer

Answer: a [Reason:] In Theta mode of replication a circular parental chromosome is replicated to two circular daughter chromosomes, in each of which one strand of the parental DNA molecule is conserved and a complementary strand is newly synthesized.

8. Eukaryotes replicate their DNA from one origin or growing point per molecule.
a) True
b) False

View Answer

Answer: b [Reason:] Procaryotes replicate their DNA from one origin or growing point per molecule while eukaryotes replicate from many origins per molecule.Replication may occur in either a unidirectional or bidirectional manner from each origin.

9. DNA gyrase is a ______________ protein.
a) helix-unwinding
b) helix-destabilizing
c) helix-relaxing
d) helix-winding

View Answer

Answer: c [Reason:] DNA gyrase is a helix-relaxing protein which work along with other enzymes and participate in opening the parental DNA helix ahead of the replication fork.

10. Which of the following enzyme removes the RNA primer with its 5’-nuclease activity?
a) DNA polymerase I
b) DNA polymerase II
c) DNA polymerase III
d) RNA polymerase

View Answer

Answer: a [Reason:] DNA polymerase I removes the RNA primer with its 5”-nuclease activity; simultaneously it fills in the gap with DNA via its 3’-polymerase activity.

Interview MCQ Set 4

1. Which of the following organisms produces neurotoxin as a virulence factor?
a) Bacillus anthracis
b) Clostridium tetani
c) Streptococcus pneumoniae
d) Staphylococcus aureus

View Answer

Answer: b [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: d [Reason:] 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 multiplication of clostridia spores?
a) 109 to116 degree F
b) 100 degree F
c) -2 to 16 degree F
d) 30-40 degree F

View Answer

Answer: a [Reason:] If the meat or poultry is cooked at a temperature which 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: a [Reason:] The detection of persons susceptible to diphtheria by means of the Schick test has made the disease rare in 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

View Answer

Answer: c [Reason:] M.bovis and M. tuberculosis are pathogenic species and both cause tuberculosis. They regularly exhibit susceptibility to antituberculosis drugs.

Interview MCQ Set 5

1. Which among the following are the most important agents for carbon dioxide fixation?
a) bacteria
b) fungi
c) algae
d) protozoa

View Answer

Answer: c [Reason:] Green plants and algae are the most important agents of carbon dioxide fixation.

2. Fresh air contains approximately ______ percent carbon dioxide by volume.
a) 0.01
b) 2
c) 5
d) 0.03

View Answer

Answer: d [Reason:] Fresh air contains approximately 0.03 percent carbon dioxide by volume.The end product, carbon dioxide, from the degradation of organic carbon compounds are released into the air and soil.

3. Cellulose is degraded to cellobiose by the enzyme __________________
a) cellulase
b) beta-glucosidase
c) hexokinase
d) cellulose dehydrogenase

View Answer

Answer: a [Reason:] The most abundant organic material in plants is cellulose.The initial enzymatic at-tack is by cellulase which splits this long-chain polymer of glucose to cellobiose.which contains two glucose units.

4. The amount of organic material in the forest soil remains approximately the same from year to year.
a)True
b) False

View Answer

Answer: a [Reason:] Under most natural systems of vegetation, e.g., forests, the amount of organic ma-terial in the soil remains approximately the same from year to year.This results from a balance established between the annual litter fall and death of the plants and the capacity of microorgan-isms to degrade these tissues.

5. In carbon cycle flow of energy is _________________
a) bidirectional
b) linear
c) cyclic
d) irreversible

View Answer

Answer: b [Reason:] In carbon cycle flow of energy is linear in unidirectional way through carbon dioxide in the atmosphere to organic forms of carbon in soil.

6. Cellobiose is metabolized directly by many microorganisms.
a) True
b) False

View Answer

Answer: b [Reason:] Cellobiose is split into glucose by the enzyme beta-glucosidase; glucose is metab-olized directly by microorganisms.

7. Cysteine breaks down in presence of cysteine desulfurase to give _________________
a) oxaloacetic acid
b) sulphuric acid
c) pyruvic acid
d) glyoxalate

View Answer

Answer: c [Reason:] Degradation of proteins liberates amino acids, some of which contain sulphur released by the enzymatic activity of many heterotrophic bacteria.Cysteine breaks down in presence of cysteine desulfurase to give pyruvic acid, hydrogen sulphide and ammonia.

8. Which of the following processes is performed by Thiobacillus thiooxidans?
a) converting sulphur to sulphates
b) converting sulphur to sulphides
c) converting sulphur to sulphites
d) converting organic sulphur to inorganic sulphur

View Answer

Answer: a [Reason:] Thiobacillus thiooxidans, an autotroph, is capable of oxidizing elemental sulphur to sulphates.

9. Sulphates are reduced to hydrogen sulphide by _____________________
a) Desulfotomaculum sp.
b) Thiobacillus thiooxidans
c) Photosynthetic sulfur bacteria
d) Rhodospirillum

View Answer

Answer: a [Reason:] Sulphates are reduced to hydrogen sulphide by soil microorganisms like Desulfotomaculum species. Like calcium sulphate gives us hydrogen sulphide and calcium hydroxide.

10. The Winogradsky column experiment is done in the dark.
a) True
b) False

View Answer

Answer: b [Reason:] A laboratory technique which facilitates isolation of various sulfur-metabolilizing bacteria is the Winogradsky column.The column contains mud,CaSO4, plant tissue, and water.It is exposed to daylight and incubated at room temperature.

11. The reduction of sulphates and sulphites to hydrogen sulphide is done by which group of bacteria?
a) aerobic sulfate-reducing bacteria
b) photosynthetic sulphur bacteria
c) anaerobic sulphate-reducing bacteria
d) heterotrophic bacteria

View Answer

Answer: c [Reason:] Organic acids serve as the electron donors for the reduction of sulfates to sulfites to hydrogen sulfide by anaerobic sulfate-reducing bacteria.

12. Which among the following develop in the upper portion of the Winogradsky column?
a) Sulfate-reducing bacteria
b) Green-sulfur bacteria
c) Purple-sulfur bacteria
d) Thiobacilli

View Answer

Answer: d [Reason:] The aerobic sulfur-metabolizing bacteria,Thiobacillus sp..,develop in the upper portion of the column and oxidize reduced sulfur compounds.

13. Purple and green sulfur bacteria use ___________________ as the electron donor to reduce carbon dioxide.
a) S2-
b) SO42-
c) H2S
d) Organic acids

View Answer

Answer: c [Reason:] Photosynthetic microorganisms such as the purple and green sulfur bacteria use hydrogen sulphide as the electron donor to reduce carbon dioxide.

14. Which among the following is a non-sulfur purple bacteria?
a) Rhodomicrobium
b) Thiobacillus
c) Chromatium
d) Chlorobium

View Answer

Answer: a [Reason:] The non-sulfur bacteria purple bacteria like Rhodomicrobium,Rhodospirillum. Rhodopseudomonas are facultative phototrophs and can utilize sulfide at low levels.