MICROBIOLOGY of FOODS Multiple Choice Questions :-
1. Most spoilage bacteria grow at
A. acidic pH
B. alkaline pH
C. neutral pH
D. any of the pH
Answer: C
2. The microbiological examination of coliform bacteria in foods preferably use
A. MacConkey broth
B. violet Red Bile agar
C. eosine Methylene blue agar
D. all of these
Answer: D
3. Which of the following acid will have higher bacteriostatic effect at a given pH?
A. Acetic acid
B. Tartaric acid
C. Citric acid
D. Maleic acid
Answer: A
4. Which of the following is not true for the thermal resistance of the bacterial cells?
A. Cocci are usually more resistant than rods
B. Higher the optimal and maximal temperatures for growth, higher the resistance
C. Bacteria that clump considerably or form capsules are difficult to kill
D. Cells low in lipid content are harder to kill than other cells
Answer: D
5. Water activity can act as
A. an intrinsic factor determining the likelihood of microbial proliferation
B. a processing factor
C. an extrinsic factor
D. all of the above
Answer: D
6. Enumeration of microorganism refers to
A. either spiral plating, pour plate or spread plate of a food suspension on to a suitable selective agar, or non-selective plate, depending on the test
B. either spiral plating, pour plate or spread plate of a food suspension on to a suitable selective agar
C. non-selective plating, depending on the test
D. none of the above
Answer: A
7. The different ACC’s between food categories reflect the
A. expected level of contamination of the raw material
B. potential for microbial growth during storage
C. potential shelf life
D. all of the above
Answer: D
8. Examination of the presence / absence of organisms refers to
A. incubation of a food suspension in an enrichment medium followed by inoculation on to a suitable selective medium.
B. incubation of a food suspension in an enrichment medium followed by inoculation on to a non-selective medium.
C. incubation of a food suspension in an enrichment medium
D. none of the above
Answer: A
9. Plate count of bacteria in foods generally use the plating medium consisting of
A. peptone, yeast extract, glucose, sodium chloride, agar and distilled water
B. yeast extract, glucose, sodium chloride, agar and distilled water
C. peptone, glucose, sodium chloride, agar and distilled water
D. peptone, yeast extract, glucose, sodium chloride and distilled water
Answer: A
10. What are the intrinsic factors for the microbial growth?
A. pH
B. Moisture
C. Oxidation-Reduction Potential
D. All of these
Answer: D
MICROBIOLOGY of FOODS Objective Type Questions with Answers
11. Yeast and mould count determination requires-
A. nutrient agar
B. acidified potato glucose agar
C. MacConkey agar
D. violet Red Bile agar
Answer: B
12. The time temperature combination for HTST paterurization of 71.1°C for 15 sec is selected on the basis of
A. Coxiella Burnetii
B. E. coli
C. B. subtilis
D. C. botulinum
Answer: A
13. Aerobic Colony Count (ACC), is also known as
A. Total viable count (TVC)
B. Aerobic plate count (APC)
C. Standard plate count (SPC)
D. All of these
Answer: D
14. Which of the following is true about ISO 2002 method for Salmonella detection?
A. Selenite cystine (SC) broth is replaced by Muller Kauffmann tetrathionate novobiocin broth (MKTTn)
B. Rappaport Vassiliadis (RV) broth has been replaced by Rappaport Vassiliadis Soya (RVS) broth
C. XLD is the first isolation medium rather than BGA
D. All of these
Answer: D
15. Suspected colonies of Staphylococcus aureus when grown on Baird-Parker medium shall show
A. coagulase activity
B. protease activity
C. catalase activity
D. none of these
Answer: A
16. A psychrophilic halophile would be a microbe that prefers
A. cold temperatures and increased amounts of salt
B. warm temperatures and increased amounts of pressure
C. cold temperatures and the absence of oxygen
D. warm temperatures and increased amounts of acid
Answer: A
17. NaCl can act as
A. antagonist at optimal concentrations
B. synergistically if added in excess of optimum level
C. Both (a) and (b)
D. None of the above
Answer: C
18. The color of spore in Dorner’s method?
A. Black
B. White
C. Red
D. Yellow
Answer: D
19. Method most suitable for sterilizing blood serum is
A. Arnold method
B. Chemical method
C. Autoclave
D. Filteration
Answer: D
20. Which of the following methods of flagella staining uses silver nitrate as a staining agent?
A. West method
B. ray method
C. Arnold method
D. None of the above
Answer: A
21. Wirtz-Conklin method is used for:
A. cell wall staining
B. Flagella stainin
C. Endospore staining
D. Capsule staining
Answer: C
22. Mordant used in staining of flagella:
A. Ethyl chloride
B. Tannic acid
C. Cetyl pyrimidine chloride
D. Potassium picolinate
Answer: B
23. Decolorizer used in gram staining is:
A. Water
B. Alcohol
C. Benzene
D. Any of the above
Answer: B
24. The decolorizer used in capsule staining is:
A. Cetyl pyrimidine chloride
B. Copper sulphate
C. Alcohol
D. Benzene hexachloride
Answer: B
25. Which staining technique is best suited to know the shape of microorganisms ?
A. Positive staining
B. Negative staining
C. Fluorescent staining
D. Acid fast staining
Answer: B
26. Which staining technique is best suited to know the presence of mycobacterium species in culture?
A. Positive staining
B. Negative stainingg
C. Fluorescent stainin
D. Acid fast stainin
Answer: D
27. The decolorizer used in case of flagella staining is:
A. Water
B. Alcohol
C. Calcium hydroxide
D. Hexane
Answer: A
28. Peziza shows which of the following fruiting bodies?
A. Cleistothecium
B. Apothecium
C. Perithecium
D. Hypothesium
Answer: B
29. Which of the following statements is/are correct?
A. Generation time is the time required by the cell to double
B. Generation time is not same for all microorganisms
C. Generation time is not same for a microorganism under all conditions
D. All the above
Answer: D
30. Rate of penetration of medium into a bacterial cell does not depend on:
A. Nutrient of the medium
B. Growth phase
C. Temperature
D. None
Answer: D
31. Which of the following is NOT a platingg technique?
A. Spread plate technique
B. Tilt plate technique
C. Streak plate technique
D. Pour plate technique
Answer: B
32. Which of the following statements is/are NOT CORRECT?
A. The swab method is best suited for flexible, uneven, and heavily contaminated surfaces
B. Impingers are not suitable in air sampling because in this method specific quantity of air is difficult to be sampled
C. In case of ravimetric and volumetric samplin method, microbial concentrations can be reported as “per volume of diluent”
D. All of the above
Answer: B
33. Which of the following statements is/are correct?
A. Growth rate is recipprocal of generation time
B. Generation time of Bacillus subtilis is 8 min at 37 degree C in broth
C. Both a and b
D. Neither a nor b
Answer: A
34. Which of the following statements regarding log growth phase of bacterial growth curve is/are correct?
A. Cell division is at constant rate
B. Growth rate is maximum and constant
C. GGeneration time is shortest and constant
D. All of the above
Answer: D
35. Which of the following statements is/are not correct for the lag phase of the bacterial growth curve?
A. Gradual increase in cell number
B. This phase is used for fermentation
C. It is the phase of cell enlargement
D. All of the above
Answer: D
36. The difference between a chemostat and a turbidostat is/are:
A. The dilution rate in a turbidostart varies and in chemostat it is constant
B. Unlike chemostat, turbidostat doen not have any limiting nutrient
C. Turbidostat operates best at high dilution rates; the chemostat is most stable and effective at lower dilution rate
D. All ofthe above
Answer: D
37. Turbidostat and chemostat are:
A. Continuous culture system
B. Instrument to enumerate the microbial cells
C. Type of sterilizer
D. Type of fermenter
Answer: A
38. The rate of nutrient exchange in a chemostat is expressed as:
A. Maintenance energy
B. Dilution rate
C. Flow rate of medium through the culture vessel
D. None of the above
Answer: B
39. A positive nitrate reduction test results in color:
A. Red
B. Blue
C. Green
D. Yellow
Answer: A
40. Which of the following is a rapid system for detecting the presence of foodborne pathoens?
A. PCR
B. Swab method
C. Streak technique
D. All of the above
Answer: A
41. The dye used in dye reduction test is/are:
A. Resazurin
B. Methylene blue
C. Both a and b
D. None
Answer: C
42. During the dye reduction test the resazurin is converted to:
A. Epinephrine
B. Resorufin
C. Restacline
D. None
Answer: B
43. During the dye reduction test using reazurin the color change taking place is:
A. Blue to green
B. Green to blue
C. Pink to blue
D. Blue to pink
Answer: D
44. Which of the following is NOT a method for quantifying the microbial population?
A. Gravimetric method
B. Total Plate Count (TPC) method
C. Standard plate counts (SPC) method
D. Most probable numbers (MPN) method
Answer: A
45. Which of the following is an example of protozoa?
A. Amoeba
B. Aspergillus
C. HIV
D. Hydra
Answer: A
46. Which of the following stains can be used to differentiate between dead and living cells?
A. Acridine orange
B. Methylene blue
C. Resazurin
D. All of the above
Answer: A
47. Acridine orange gives …………. color to the dead cells:
A. Orange
B. Blue
C. Green
D. Pink
Answer: C
48. DEFT is based on:
A. Conductance
B. Direct microbial count using microscope
C. Turbidit
D. Cellular activity
Answer: B
49. During measurement of the microbial load by ATP method, the oxidation of which compound is taken into consideration?
A. ATP
B. Luciferin
C. Acridine
D. Chitin
Answer: B
50. Cyanobacteria are also called:
A. Blue Green algae
B. Red Brown algae
C. Black & White algae
D. Green yellow algae
Answer: A
51. Prominent difference between prokaryotic and eukaryotic cells is the:
A. Larger size of prokaryotes
B. Lack of pigments in eukaryotes
C. Presence of a nucleus in eukaryotes
D. Presence of a cell wall in prokaryotes
Answer: C
52. The following part was absent in Leeuwenhoek’s microscope:
A. Focusing screw
B. Lens
C. Specimen holder
D. Condenser
Answer: D
53. The scientist who first disapproved the theory of spontaneous generation was:
A. Joseph Lister
B. Robert Koch
C. Francesco Redi
D. Louis Pasteur
Answer: C
54. The most responsible early microbiologist for developing the sterile laboratory technique was:
A. Louis Pasteur
B. Carl Von Line
C. Robert Koch
D. John Tyndall
Answer: C
55. The correct order of the taxonomic categories, going from most specific to most general is:
A. Kingdom, phylum, class, order, family, genus, species
B. Division, domain, kingdom, class, family, genus, species
C. Species, genus, family, order, class, phylum, kingdom
D. Species, family, class, order, phylum, kingdom
Answer: C
56. The term culture refers to the growth of microorganism in:
A. Rapid, an incubator
B. Macroscopic, media
C. Microscopic, the body
D. Artificial, colonies
Answer: B
57. A mixed culture is:
A. The same as a contained culture
B. One that has been adequately stirred
C. One that contains two or more known species
D. A pond sample containing algae and protozoa
Answer: C
58. Agar is superior to gelatin as a solidifying agent because agar:
A. Does not melt at room temperature
B. Solidifies at 75 degree C
C. Is not usually decomposed by microorganism
D. Both a and c
Answer: D
59. A subculture is a:
A. Colony growing beneath the media surface
B. Culture made from a contaminant
C. Culture made in an embryo
D. Culture made from an isolated colony
Answer: D
60. The specimen for an electron microscope is always:
A. Stained with dyes
B. Sliced into thin sections
C. Killed
D. Viewed directly
Answer: C
61. Which of the following polymers is/are present in bacterial cell wall?
A. Techoic acids
B. Polysaccharide
C. Polypeptide
D. All of the above
Answer: D
62. Motility is best seen with a:
A. Hanging drop preparation
B. Negative stain
C. Streak plate
D. Flagellar
Answer: A
63. Bacteria tend to stain more readily with cationic dyes because:
A. Contain large amounts of alkaline substances
B. Contain large amounts of acidic substances
C. Are neutral
D. Have thick cell wall
Answer: B
64. The major locomotor structure in bacteria are:
A. Flagggella
B. Pili
C. Fimbriae
D. Cilia
Answer: A
A. Gram-positive, genetic exchange
B. Gram-positive, attachment
C. Gram-negative, genetic exchange
D. Gram-negative, protection
Answer: C
66. A bacteria having flagella on both the sides are called as:
A. Monotrichus
B. Amphitrichus
C. Lophotrichus
D. Peritrichus
Answer: B
67. In general, fungi derive nutrients through:
A. Photosynthesis
B. Engulfing bacteria
C. Digesting organic substrates
D. Parasitism
Answer: C
68. A conidium is a/an spore, and a zygospore is a/an:
A. Sexual, asexual
B. Free, endo
C. Ascomycete, basidiomycete
D. Asexual, sexual
Answer: D
69. A virus is a tiny infectious:
A. Cell
B. Livin thing
C. Particle
D. Nucleic acid
Answer: C
70. Viruses are known to infect:
A. Plant
B. Bacteria
C. Animals
D. All organism
Answer: D
71. The general steps in a viral multiplication cycle are:
A. Adsorption, penetration, replication, maturation and release
B. Endocytosis, uncoating, replication, assembly, budding
C. Adsorption, uncoating, duplication, assembly and lysis
D. Endocytosis, penetration, replication, maturation and exocytosis
Answer: A
72. Enveloped viruses carry surface receptors called:
A. Buds
B. Spikes
C. Fibers
D. Sheaths
Answer: B
73. An obligate halophile requires high:
A. pH
B. Temperature
C. Salt
D. Pressure
Answer: C
74. Chemoautotrophs can survive on alone:
A. Minerals
B. CO2
C. Minerals and CO2
D. Methane
Answer: C
75. Psychrophies would be expected to grow:
A. In hot springs
B. On the human body
C. At refrigeration temperatures
D. At low pH
Answer: C