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Interview MCQ Set 1

1. The temperature that allows for most rapid growth during a short period of time is known as __________
a Minimum Temperature
b) Maximum Temperature
c) Optimum Temperature
d) Growth Temperature

View Answer

Answer: c [Reason:] The temperature that allows for most rapid growth during a short period of time(12 to 24 hrs) is known as the optimum temperature. Maximum temperature for growth lies very close to the optimum temperature whereas minimum temperature for growth is usually much lower than the optimum.

2. Mesophiles are group of bacteria that grow within the temperature range of?
a) 0-20 degree Celsius
b) 25-40 degree Celsius
c) 45-60 degree Celsius
d) more than 60 degree Celsius

View Answer

Answer: b [Reason:] Mesophiles grow best within a temperature range of 25 to 40 degree Celsius.All bacteria that are pathogenic for humans and warm-blooded animals are mesophiles, most growing best at about body temperature(37 degree Celsius).

3. Which of the following factors are responsible for the stability of thermophiles at high temperatures?
a) increased leakage of cell components
b) presence of large no. of polar amino acids and alpha-helix protein
c) thermal stability of ribosomes
d) presence of Inositol diphosphate and thermal stability of ribosomes

View Answer

Answer: d [Reason:] Factors that have been implicated in the ability to grow at high temperature is an increased thermal stability of ribosomes.The cytoplasmic membrane of thermophiles also contains Inositol diphosphate or Inositol triphosphate which can tolerate high temperature and maintains the fluidity of the membrane.

4. The bacterium Staphylococcus aureus is which type of bacteria?
a) Psychrophile
b) Mesophile
c) Thermophile
d) Mesophile and psychrophile

View Answer

Answer: b [Reason:]Staphylococcus aureus is a mesophilic bacteria which can grow in the temperature range of 6.5-46 degree Celsius and has an optimum temperature at 30-37 degree Celsius.

5. Microaerophilic bacteria require low levels of oxygen for growth.
a)True
b) False

View Answer

Answer: a [Reason:] Microaerophilic bacteria require low levels of oxygen for growth but it cannot tolerate the level of oxygen present in an air atmosphere.

6. The Reactive Oxygen Species(ROS) poduced by some bacteria are degraded by which of the following enzymes?
a) Peroxidase
b) Lyase
c) Catalase
d) Superoxide dismutase, Catalase and Peroxidase

View Answer

Answer: d [Reason:] In some cases, oxygen may accept large number of free electrons and produces Reactive Oxygen Species (ROS).They are harmful as they degrade macromolecules required for growth and nutrition. But aerobic bacteria contains three different enzymes-Superoxide dismutase, Catalase and Peroxidase which eliminates the different ROS.

7. Which of the following ROS is a powerful oxidizing agent?
a) Superoxide radical
b) Hydrogen peroxide
c) Hydroxyl radical
d) Singlet oxygen

View Answer

Answer: b [Reason:] Superoxide radicals form toxic substances such as hydrogen peroxide.Hydrogen peroxide is not a free radical, but it is a powerful oxidizing agent .

8. The GasPak system is suitable for which of the following?
a) Aerobic bacteria
b) Anaerobic bacteria
c) Facultatively anaerobic bacteria
d) Microaerophilic bacteria

View Answer

Answer: b [Reason:] GasPak Jar is a system for anaerobic bacteria. In this jar media is inoculated and placed in the jar. To this water is added, causing the evolution of Hydrogen gas and Carbon dioxide. The Hydrogen gas reacts with oxygen on the surface of the palladium catalyst, forming water and establishing anaerobic conditions.

9. Which of the following are functions of phosphates used in the preparation of media?
a) they act as buffer
b) source of phosphorous
c) act as “reserve alkali”
d) they act as buffer and is a source of phosphorous

View Answer

Answer: d [Reason:] The phosphates are used widely in the preparation of media because they are the only inorganic agents that buffer in the physiologically important range around neutrality and that are relatively non-toxic to microorganisms. In addition, they provide a source of phosphorous, which is an essential element of growth.

10. The optimum pH for the growth of most bacteria lies between_______
a) 5-9
b) 6.5-7.5
c) 2-3.5
d) 9-9.5

View Answer

Answer: b [Reason:] pH is an important physical condition controlling the growth of bacteria. For most bacteria, the optimum pH for growth lies between 6.5 and 7.5.This pH of the media is maintained by using a buffer into the medium.

Interview MCQ Set 2

1. Pathogenic fungi have a temperature optimum at __________
a) 30 to 37 degree celsius
b) 22 to 30 degree celsius
c) 37 to 42 degree celsius
d) 42 to 50 degree celsius

View Answer

Answer: a [Reason:] Fungi grow over a wide range of temperature.Pathogenic species have a higher temperature optimum, generally 30 to 37 degree Celsius.

2. Sabouraud media for the growth of fungi is composed of ____________________
a) glucose and ammonia
b) maltose and peptone
c) sucrose and peptone
d) peptone

View Answer

Answer: b [Reason:] One of the best known and oldest media for growth of fungi is Sabouraud media that contains maltose and peptone as its principal ingredients.

3. Sabouraud media has _________________________
a) high ph,low sugar concentration
b) high ph,moderate sugar concentration
c) low ph,high sugar concentration
d) low ph,moderate sugar concentration

View Answer

Answer: c [Reason:] Sabouraud media is widely used for the isolation of molds and certain yeasts.Its partial selective action is due to the high sugar concentration and low pH.

4. Jams and jellies are spoiled by both bacteria and fungi.
a) True
b) False

View Answer

Answer: b [Reason:] Yeasts and molds can grow in a substrate or medium containing concentrations of sugars that inhibit most bacteria; this is why jams and jellies may be spoiled by molds but not by bacteria.

5. What are the cell wall structural components of fungi?
a) peptidoglycan
b) cellulose
c) chitin
d) chitin,cellulose, or hemicellulose

View Answer

Answer: d [Reason:] The cell wall structural components of fungi are chitin,cellulose, or hemicellulose whereas the bacterial cell wall is composed of peptidoglycan.

6. The optimum pH for the growth of fungi is ____________
a) 7.8-9.0
b) 12-14
c) 3.8-5.6
d) 1.0-2.0

View Answer

Answer: c [Reason:] The optimum pH for the growth of fungi is 3.8-5.6.Acidic media (pH 5.6) are tolerated by molds but are inhibitory to most bacteria.

7. Which of the following are the oxygen requirements of molds?
a) Strictly aerobic
b) Facultatively aerobic
c) Anaerobic
d) Microaerophilic

View Answer

Answer: a [Reason:] Moulds are strictly aerobic whereas yeasts are facultative organisms.

8. Fungi are sensitive to which of the following antibiotics?
a) penicillins
b) tetracyclins
c) chloramphenicol
d) griseofulvin

View Answer

Answer: d [Reason:] Fungi are resistant to penicillins,tetracyclins,chloramphenicol but are sensitive to griseofulvin.

9. Ordinary inoculating loop can be used for inoculation of yeasts.
a) True
b) False

View Answer

Answer: True [Reason:] Ordinary inoculating loop used for bacteria is suitable for the inoculation of yeasts.But the needle used for molds is stiffer and has a flattened tip for cutting the mycelium.

Interview MCQ Set 3

1. The temperatures used for canning foods ranges from ____________________
a) 0-20 degree C
b) 20-60 degree C
c) 60-100 degree C
d) 100-121 degree C

View Answer

Answer: d [Reason:] The temperatures used for canning foods ranging from 100 degree C for high-acid foods to 121 degree C for low-acid foods.

2. In the high-temperature short-time (HTST) method of pasteurization, milk is exposed to a temperature of _________
a) 132 degree F
b) 145 degree F
c) 161 degree F
d) 120 degree F

View Answer

Answer: c [Reason:] The HTST process employs equipment capable of exposing milk to a temperature of 161 degree F (71.7 degree C) for 15 secs.

3. Sterilization occurs at high temperatures for long periods of time.
a) True
b) False

View Answer

Answer: b [Reason:] Sterilization exposes milk to ultrahigh temperatures for very short periods of time, for example, 300 degree F (148.9 degree C) for 1 to 2 seconds.

4. Which of the following microorganism survive at -9 to -17 degree C?
a) Salmonella
b) Staphylococci
c) Bacilli
d) Clostridium

View Answer

Answer: a [Reason:] Species of Salmonella survive for longer periods of time at -9 to -17 degree C which is unlike the situation in which microbial count of most frozen foods decreases during storage.

5. Which of the following microorganism is eliminated in canned foods?
a) Mycobacterium tuberculosis
b) Coxiella burnetii
c) Clostridium botulinum
d) Lactobacillus

View Answer

Answer: c [Reason:] The most important organism to be eliminated in canned foods is the spore forming anaerobe Clostridium botulinum, which is capable of producing a very potent lethal toxin.

6. Phosphatase enzyme present in milk is destroyed in which of the following processes?
a) Sterilization
b) Canning
c) Dehydration
d) Pasteurization

View Answer

Answer: d [Reason:] Phosphatase is an enzyme present in raw milk and in many tissues which is destroyed by adequate pasteurization.

7. Jellies and jams are rarely affected by bacterial action.
a) True
b) False

View Answer

Answer: a [Reason:] Jellies and jams are rarely affected by bacterial action because of high sugar content.However it is uncommon to find mold growth on the surface of jelly which has been exposed to air.

8. Which chemical is used to inhibit mold growth in bread?
a) benzoic acid
b) nitrates
c) sorbic acid
d) lactic acid

View Answer

Answer: c [Reason:] Sorbic acid and propionic acid are used to inhibit mold growth in bread.They are organic in nature.

9. Acetic acid and lactic acid are used for __________________
a) curing meats
b) preservation of color
c) preservation of pickles
d) inhibiting mold growth

View Answer

Answer: c [Reason:] Foods prepared from fermentation processes,e.g., sauerkraut,pickles,and silage for animals are preserved mainly by acetic,lactic and propionic acids produced during the microbial fermentation.

10. Which of the following method is used for treatment of water used for the depuration of shellfish?
a) Chemicals
b) Radiation
c) Low temperature
d) Osmotic pressure

View Answer

Answer: b [Reason:] Radiations are used in the food industry,control of surface growth on bakery products,sanitation of equipment and treatment of water used for the depuration (cleansing) of shellfish.

Interview MCQ Set 4

1. The respiratory chain of bacteria is associated with the _____________
a) miitochondrial membrane
b) cytoplasmic membrane
c) cell wall
d) cytoplasm

View Answer

Answer: b [Reason:] The respiratory chain of bacteria is associated with the cytoplasmic membrane and that of eukaryotes is present in mitochondrial membrane.

2.The prosthetic group of a cytochrome contains how many iron atoms?
a) one
b) two
c) three
d) four

View Answer

Answer: a [Reason:] Cytochromes are a major class of oxidative enzymes whose prosthetic group is a derivative of heme and contains a single iron atom, which is responsible for the oxidative or reductive properties of the enzyme.

3. Among the following which can directly react with oxygen?
a) cytochrome c
b) cytochrome c1
c) cytochrome a
d) cytochrome a3

View Answer

Answer: d [Reason:] Cytochrome a and a3 together are called cytochrome oxidase, both of them contain copper. But only cytochrome a3 can react directly with oxygen.

4. How many ATP molecules are formed for per molecule of FADH2 reoxidized?
a) 3
b) 1
c) 2
d) 4

View Answer

Answer: c [Reason:] Three ATP are formed per molecule of NADH2 reoxidized but only two ATP molecules are formed per molecule of FADH2 reoxidized, because of the high energy of NADH2.

5 .In aerobic respiration the terminal electron acceptor is oxygen,nitrate,sulphate, etc.
a) True
b) False

View Answer

Answer: b [Reason:] In aerobic respiration the terminal electron acceptor is oxygen; in anaerobic respiration the final electron acceptor is nitrate, sulphate and carbonate.

6. In photosynthesis by green plants, algae, cyanobacteria which of the following acts as terminal electron acceptor?
a) Water
b) Oxygen
c) NADP+
d) FAD+

View Answer

Answer: c [Reason:] In photosynthesis by green plants, algae and cyanobacteria, water serves as a primary electron donor and NADP+ as a terminal electron acceptor.

7. A reducing agent will accept electrons and an oxidizing agent will donate electrons.
a) True
b) False

View Answer

Answer: b [Reason:] An oxidizing agent will absorb electrons and will therefore become reduced whereas a reducing agent donates electrons, becoming oxidized in the process.

8. Keq is greater than 1.0 depending on which of the following conditions?
a) standard free energy change is negative
b) standard free energy change is positive
c) chemical reaction proceeds in reverse direction
d) products are not formed

View Answer

Answer: a [Reason:] When standard free energy change is negative value then Keq is greater than 1.0 and the formation of products is favoured.

Interview MCQ Set 5

1. The amino acids for protein synthesis is activated by the enzyme ______________
a) rna synthetase
b) aminoacyl-tRNA synthetase
c) tRNA synthetase
d) aminoacyl-mRNA synthetase

View Answer

Answer: b [Reason:] The first step in protein synthesis is the activation of amino acids.The amino acids are activated by amino-acid activating enzymes called aminoacyl-tRNA synthetase.

2. The activation of amino acids require energy.
a) True
b) False

View Answer

Answer: a [Reason:] The activation of amino acids for protein synthesis requires energy in the form of ATP.There is a specific activating enzyme for each kind of amino acid.

3. tRNA has a _______________ structure.
a) strand-like
b) ball-like
c) clover-leaf
d) leaf-like

View Answer

Answer: c [Reason:] tRNA has a clover-leaf structure.The tRNA functions in protein synthesis to carry amino acids to, and recognize codons in, mRNA.

4. Transfer RNA is a single chain of ___________ nucleotides.
a) 340
b) about 100
c) about 80
d) 200

View Answer

Answer: c [Reason:] Transfer RNA is a single chain of about 80 nucleotides that is folded back upon itself and held in a clover-leaf arrangement by means of hydrogen bonding due to complementary base pairing.

5. The terminal sequence of nucleotides in all tRNA is __________
a) ACC
b) UGC
c) UCC
d) AGC

View Answer

Answer: a [Reason:] The terminal sequence of nucleotides is adenylic-cytidylic-cytidilic (ACC) and is found in all tRNA. The amino acid to be carried is linked to the terminal nucleotide containing adenine.

6.The tRNA carries amino acids to the ____________
a) rRNA
b) mRNA
c) sRNA
d) hnRNA

View Answer

Answer: b [Reason:] The tRNA carries amino acid to the mRNA attached to the surface of the ribosome. Here the amino acid is added to a growing polypeptide chain.

7. The ribosome of E.coli is made up of which two subunits?
a) 60S and 40S
b) 60S and 30S
c) 50S and 40S
d) 50S and 30S

View Answer

Answer: d [Reason:] The ribosomes of E.coli have been studied extensively and have been found to consist of two subunits. The larger subunit is a 50S particle, while the smaller unit is a 30S particle.

8. S,the Svedberg unit is a measure of ____________________________
a) the size of the ribosome
b) the composition of the ribosome
c) how fast a particle sediments during ultracentrifugation.
d) how the subunits combine in a ribosome

View Answer

Answer: c [Reason:] S is the Svedberg unit, a measure of how fast particle sediments during ultracentrifugation. The association of a 30S and 50S subunit to form a 70S ribosome shows that the sedimentation behavior of the 70S ribosome is not a simple addition of the units of the smaller particles.

9. Which of the following statement is correct?
a) The ribosome binds to any end of a mRNA
b) CTP is required for activation of amino acids
c) Activated amino acids bind to the 5’ end of respective tRNA molecule
d) The protein chain dissociates from the last tRNA molecule

View Answer

Answer: d [Reason:] The amino group of the amino acid on the second tRNA reacts with the active terminal carboxyl group on the amino acid of the first tRNA to form a dipeptide; the first tRNA is then released. The process is continued till the peptide chain is complete. Termination takes place at one of the nonsense codons and the chain dissociates from the last tRNA molecule.