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BCEE Flashcards

1
Q

The contents in jet loop reactor are mixed through
A. compressed air
B. a mechanical agitator
C. external pumping
D. any of these

A

C

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2
Q

The specific growth rate (μ) is defined as
A. the concentration of biomass in the reactor
B. rate of increase of total biomass in a reactor
C. the rate of individual cells division or increase in their
biomass
D. the rate of cell death

A

C

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3
Q

The number of baffles in a standard stirred tank bioreactor is
A. 8
B. 6
C. 4
D. 2

A

C

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4
Q

In the stationary phase
A. growth is proportional to death
B. growth rate is equal to death rate
C. growth rate is lesser than death rate
D. no co-relation exist between death rate and growth rate

A

B

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5
Q

Which of the following is an example of a mathematical model?
A. Volume of cuboid = length x breadth x height
B. The Monod Model
C. The Michaelis Menten Equation
D. All of the above

A

D

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6
Q

Chemostats work on the principle of
A. maintaining constant volume of culture medium
B. maintaining continuous flow of nutrients
C. maintaining uniform nutrients concentration
D. operating at higher pressure

A

C

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7
Q

During the exponential phase the maximum specific growth rate
equals specific growth rate as
A. concentration of the growth limiting substrate is much
less than the monod constant
B. concentration of growth limiting substrate is much
greater than the monod constant
C. specific growth rate increases exponentially
D. concentration of the growth limiting substrate is equal
to the monod constant

A

B

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8
Q

An internal draft tube is preferred to an external draft tube
because
A. it is easier to clean and sterilize a reactor
B. it is cheaper to build a reactor with an internal draft
tube
C. Both (a) and (b)
D. none of the above

A

A

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9
Q

A functional relationship between the specific growth rate and
essential compounds concentration was proposed by Monod in
A. 1958
B. 1946
C. 1942
D. 1950

A

C

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10
Q

Lag phase occurs mainly due to
A. acclimatization with new environment and substrate
B. higher growth temperature
C. substrate disliking
D. variation in substrate concentration

A

A

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11
Q

In a batch reactor specific growth rate
A. remains constant throughout the process
B. increases exponentially
C. changes during the fermentation
D. is highest during the stationary phase

A

C

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12
Q

Residence time distribution (RTD) of a reactor is independent of
A. micro mixing
B. volume of reactor
C. height of the reactor
D. width of the reactor

A

A

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13
Q

The optical density sometimes drops during the lag phase
because
A. cells tend to grow without dividing leading to a
decrease in the surface area to volume ratio
B. of fast cell growth causing them to fill up with DNA
C. cells swell up with water
D. cells swell up with RNA

A

A

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14
Q

Biomass concentrations during fermentation is
A. diluting the samples to optical density less than 0.3
B. monitored by controlling the changes in biomass
concentrations
C. considering that optical density is proportional to the
surface area of the biomass in the sample
D. all of the above

A

D

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15
Q

The application of just in time (JIT) manufacturing techniques in
biotechnology is important because
A. raw materials used in biotechnology are biodegradable
B. the products of biotechnology are biodegradable
C. it is a very competitive business (d) all of the above
D. all of the above

A

D

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16
Q

The bubble column fermenter is usually limited to
A. aerobic fermentations
B. anaerobic fermentations
C. Both (a) and (b)
D. facultative fermentation

A

A

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17
Q

added and from which no waste products are removed is called
a __________ culture.
A. continuous
B. batch
C. fed-batch
D. semi continuous

A

B

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18
Q

If the specific growth rate, μ. is constant with time during the
exponential growth period, the equation correlating bacterial
number density Cn), cell number concentration with respect to
time can be expressed as
A. Cn= Cn0 exp[μ (t - t0)]
B. Cn0 = Cn exp[μ (t - t0)]
C. Cn/Cn0 =(1/μ)exp(t-t0)
D. Cn0 / Cn = (1/μ)exp(t-t0)

A

A

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19
Q

The diameter of the baffles in a standard stirred tank bioreactor
ranges from
A. 1/10th - 1/12th of the tank diameter
B. 1/3rd - 1/4th of the tank diameter
C. 1/15th - 1/20th of the tank diameter
D. 1/20th - 1/25th of the tank diameter

A

A

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20
Q

During the log phase cell numbers increase exponentially
A. because cells produce enzymes
B. because cells do not have cell membranes
C. because cells are autocatalysts
D. because the rate of cell division increases
exponentially

A

C

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21
Q

Turbidostat is recommended when continuous fermentation
needs to be carried out at
A. high dilution rates near the washout point
B. low dilution rates near the washout point
C. moderate dilution rates near the washout point
D. any intensity of dilution rates near the washout point

A

A

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22
Q

The advantage of airlift bioreactors over stirred tank bioreactors
of a similar size is
A. higher oxygen transfer rates
B. more uniform shear conditions
C. both (a) and (b)
D. less foaming

A

C

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23
Q

The specific growth rate is affected by
A. substrate concentration
B. product concentration
C. oxygen supply
D. all of these

A

D

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24
Q

Stirred tank fermenter (STF) can be employed for
A. aerobic fermentation of a wide range of cells including
microbial, animal and plant cells
B. anaerobic fermentation of a wide range of cells
including microbial, animal and plant cells
C. Both (a) and (b)
D. anaerobic fermentation of plant cells only

A

C

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25
Q

The main function(s) of a draft tube in an air lift fermenter is/are
to
A. increase the solubility of oxygen
B. distribute shear forces throughout the reactor and
minimise bubble coalescence
C. concentrate shear forces around the sparger
D. concentrate shear forces near the disengagement
zone

A

B

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26
Q

Which of the following is incorrect?
A. The mechanical agitation and aeration are effective for
suspension of cells
B. The mechanical agitation and aeration are effective for
mixing the medium
C. STF can’t be used for high viscosity medium
D. The mechanical agitation and aeration are effective for
oxygenation

A

C

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27
Q

The contents in bubble column and air lift reactor are mixed
through
A. compressed air
B. a mechanical internal moving part
C. external pumping
D. any of these

A

A

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28
Q

Which of the following statements would be appropriate while
comparing bubble column and air lift fermenter of the same
size?
A. The average bubble size is smaller in an airlift
bioreactor
B. Oxygen transfer rate is higher in an airlift bioreactor
C. The surface area for gas exchange is higher in an airlift
bioreactor
D. All of the above

A

D

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29
Q

During the lag phase
A. cells just start growing
B. cells synthesize new proteins and membrane
components
C. cells produce antibiotics to kill competing organisms
D. cells simply grow slowly

A

B

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30
Q

Concentration of the growth limiting substrate means
A. trace elements concentration
B. the concentration of the substrate that controls the
growth rate of the cells
C. sugar concentration in the fermentation medium
D. dissolved oxygen concentration

A

B

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31
Q

Tower fermentors are used for
A. continuous penicillin production
B. continuous beer production
C. production of enzymes
D. batch production of beer

A

B

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32
Q

In wastewater treatment, which bioreactor is generally used?
A. Plug flow reactor
B. Trickle bed reactor
C. Tower fermentor
D. CSTR

A

B

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33
Q

The contents in stirred tank rector are mixed through
A. compressed air
B. a mechanical agitator
C. external pumping
D. any of these

A

B

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34
Q

The height to diameter ratio (H/D) for the tank fermenters is
A. <3
B. >3
C. <1.5
D. >1.5

A

A

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35
Q

The relatively large volume (10 to 40% of total fermenter
volume) of the seed culture is employed to
A. increase the overall fermentation time
B. increase the overall yield of biomass
C. decrease the overall fermentation time
D. decrease the overall yield of product

A

C

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36
Q

In an airlift bioreactor, the air sparging region is called
A. downcomer
B. disengagement zone
C. air riser
D. none of these

A

C

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37
Q

The air riser is located on the outside of the draft tube for the
large-scale airlift bioreactors because of
A. higher oxygen transfer rates
B. a small sparge ring
C. better heat transfer efficiencies
D. all of these

A

C

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38
Q

At the end of the lag phase, when growth begins, the division
rate increases gradually and reaches a maximum value in the
exponential growth period. This transitional period is commonly
called the accelerated growth phase and is often included as a
part of the
A. lag phase
B. stationary phase
C. death phase
D. exponential growth phase

A

A

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39
Q

Which of the following(s) is/are considered the limitations of the
exponential growth model?
A. Only predicts that cells grow exponentially during the
log phase
B. It does not consider factors that causes cells growth to
stop or slow
C. Predicts cell growth at a linear rate
D. All of the above

A

B

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40
Q

To describe components of an airlift bioreactor which of the
follow-ings are generally included?
A. Disengagement zone, air riser, downcomer
B. Flotsam, jetsam, downzone
C. Air comer, disentanglement zone, downsizer
D. All of the above

A

A

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41
Q

Yield coefficient represents
A. total biomass or product produced
B. conversion efficiency of a substrate into product
C. conversion rate of a substrate into biomass or product
D. production time of biomass or product

A

B

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42
Q

The lowest biomass yield in a culture of Escherichia coli will be
in
A. an aerated batch culture containing a initial high
concentration of glucose
B. an aerated batch reactor containing an initial low
concentration of glucose
C. an aerated fed-batch reactor having a low glucose
concentration
D. an aerated continuous reactor having a low glucose
concentration

A

A

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43
Q

When two populations compete for a single growth limiting
substrate in a continuous fermenter, which organism would not
be washed out?
A. Organism maintaining the highest substrate
concentration
B. Organism maintaining the lowest substrate
concentration
C. Both (a) and (b)
D. Organism maintaining the moderate substrate
concentration

A

B

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44
Q

The lowest yield of ATP /is in
A. fermentation
B. aerobic respiration
C. anaerobic respiration
D. same in (a), (b) and (c)

A

A

45
Q

The continuous cultures are not widely used in industry because
A. they are not suited for the production of secondary
metabolites
B. contamination or mutation can have a disastrous effect
on the operation
C. the government will not approve the licensing of
pharmaceuticals produced in continuous cultures
D. all of the above

A

D

46
Q

Mixing in an anaerobic sludge blanket reactor is due to
A. rapid change in water temperatures throughout the
reactor
B. release of gases by the microbial populations
C. swimming of microbes
D. none of the above

A

B

47
Q

In batch culture, protogon is produced from peptone during the
stationary phase with a yield of 0.4 protogon mg per g of
peptone. If it is to be produced in a chemostat at a dilution rate
of 0.5 h-1 from a medium containing 10 g.l-1 of peptone, then the
rate of protogon synthesis would be
A. 0 g.l-1h-1
B. 0.5 g.l-1h-1
C. 1 g.l-1h-1
D. 2 g.l-1h-1

A

A

48
Q

Formation of end product by Lactococcus lactis will become
non-growth associated as lactic acid accumulates because
A. cells will redirect ATP to anabolism
B. cells will redirect NAD+ to anabolism
C. cells will redirect ATP to facilitate the diffusion of lactic
acid and H+ out of the cells
D. cells will redirect ATP to the active transport of lactic
acid and H+ out of the cells

A

D

49
Q

Which of the following would not be subjected to the “glucose
effect”?
A. Aspergillus fumigatus
B. Saccharomyces cerevisiae
C. Escherichia coli
D. Aspergillus niger

A

C

50
Q

Which of the following would not be subjected to the “glucose
effect”?
A. Aspergillus fumigatus
B. Saccharomyces cerevisiae
C. Escherichia coli
D. Aspergillus niger

A

D

51
Q

Which of the statement is true for continuous reactor at steady
state?
A. The rates of biomass, substrate and product
concentrations are zero
B. Biomass, substrate and product concentrations are
zero
C. Biomass, substrate and product concentrations do not
change with time
D. Biomass, substrate and product concentrations change
with time

A

C

52
Q

A continuous bioreactor in which only the flow rate is used to
control the rate of cell or product productivity is called
A. turbidostat
B. chemostat
C. level stat
D. pH

A

B

53
Q

For organisms growing in a chemostat, the specific growth rate
A. cannot be determined
B. can be determined from the dilution rate
C. equals to the maximum specific growth rate of the
culture
D. none of the above

A

B

54
Q

A chemostat has a liquid volume of 2 litres and is being fed at a
rate of 4 litres per hour. Dilution rate for this reactor will be
A. 2 litres
B. 2 litres per hour
C. 2 h-1
D. 4 litres per hour

A

C

55
Q

Saccharomyces cerevisiae is being grown in a chemostat
converts glucose to biomass, ethanol, glycerol and carbon
dioxide. At steady state, the concentration of glucose, biomass,
ethanol and glycerol will
A. decrease with time
B. increase with time
C. be constant
D. change randomly with time

A

C

56
Q

In aerobic yeast fermentation for production of citric acid from
alkanes using a fed-batch culture, why alkanes are slowly fed to
the yeast?
A. Citric acid is toxic to the cells
B. Alkanes cause foaming
C. Fast addition of alkanes will inhibit the cells and reduce
oxygen transfer rates
D. Fast addition of alkanes will cause the cells to grow too
quickly

A

C

57
Q

A continuous reactor has a dilution rate of 0.5 h-1. Its residence
time would be
A. ln(2)/0.5
B. ln(2) x 0.5
C. 0.5 h
D. 2 h

A

D

58
Q

Which of the following is used to calculate mass of substrate in
the reactor?
A. Flow rate x substrate concentration in the reactor
B. Volume of reactor x substrate concentration in reactor
C. Flow rate x mass of reactor
D. Volume of reactor x Flow rate

A

B

59
Q

If biomass yields are constant, then the biomass productivity of
a culture grown in continuous reactor will
A. always decrease with dilution rate
B. increase with dilution rate until washout
C. remain constant irrespective of the dilution rate
D. decrease with dilution rate until washout

A

B

60
Q

Low dissolved oxygen concentrations leads to
A. low biomass yields
B. high biomass yields
C. no effect on biomass yields
D. none of the above

A

A

61
Q

In a continuous reactor, the medium contains 40 g.l-1 of maltose
and the medium flow rate is 10 litres per hour and the effluent
contains 20 g.l-l of lactate. What is the productivity of lactate
production from this reactor?
A. 50 g maltose.l-1
B. 50 g lactate.l-1
C. 200 g maltose.l-1
D. 200 g lactate.l-1

A

D

62
Q

A fed-batch reactor containing 1 g.l-1 of substrate in 2 litre of
medium. It is fed with 1 g.l-l of substrate at the rate of 1 litre per
hour. After 10 hours, the concentration of substrate in the
reactor was 0.5 g.l-1 . The mass of substrate that was used by
the culture in the reactor was
A. 2g
B. 6g
C. 8g
D. 12g

A

B

63
Q

Toxins accumulated in a reactor can lead to low biomass yields
probably due to which of the following?
A. NAD+ is diverted away from homeostasis to anabolism
B. ATP is diverted away from homeostasis to anabolism
C. NAD+ is diverted away from anabolism to homeostasis
D. ATP is diverted away from anabolism to homeostasis

A

D

64
Q

The cellular productivity in a continuous stirred tank fermenter
(CSTF) increases with an increase in the dilution rate and
reaches a maximum value. If the dilution rate is increased
beyond the maximum point, the productivity will
A. decrease abruptly
B. increase
C. increase drastically
D. be zero

A

A

65
Q

Fluidized bed bioreactors provide higher mass transfer rates
than packed bed bioreactors because
A. mixing is higher in fluidized bed bioreactors
B. particles move with the fluid in a fluidized bed
bioreactor
C. immobilized particles are smaller in the fluidized bed
bioreactors
D. all of the above

A

B

66
Q

In fed-batch fermentation, mass of substrate utilized is
calculated using the relationship
A. initial mass of substrate in the reactor + final mass of
substrate in the reactor + flow rate x [substrate in the
feed]
B. initial mass of substrate in the reactor - final mass of
substrate in the reactor + flow rate x [substrate in the
feed]
C. initial mass of substrate in the reactor + final mass of
substrate in the reactor - flow rate x [substrate in the
feed]
D. initial mass of substrate in the reactor + final mass of
substrate in the reactor - flow rate

A

B

67
Q

Mixing per unit volume is observed to be poorest in
A. continuous packed bed reactor
B. continuous fluidized bed bioreactor
C. continuous airlift bioreactor
D. none of the above

A

A

68
Q

The growth of an organism on glucose is described by the
following Monod model parameters: μm = 0.5 h-1 and Ks =0.1 g.l
1, if the concentration of glucose in the feed is 10 g.l-1 and the
dilution rate is set to 0.4 h-1, then the steady state concentration
of glucose in the effluent will be
A. 0 g.l-1
B. 0.5 g.l-1
C. g.l-1
D. 10 g.l-1

A

B

69
Q

A continuous reactor at steady state contains 0.04 g.l-1 of
biomass and 0.02 g.l-1 of phenol. The feed contained 0.1 g.l-1 of
phenol. The biomass yield would be
A. 0.4 g.g-1
B. 0.5 g.g-1
C. g.g-1
D. 5.0 g.g-1

A

B

70
Q

A culture system with constant environmental conditions
maintained through continual provision of nutrient and removal
of wastes is called __________ culture system.
A. continuous
B. batch
C. fed-batch
D. semi continuous

A

A

71
Q

The main reason for production of antibiotics in fed batch
reactors is
A. the presence of precursors is often toxic to the cells
B. higher yields when cells enter the stationary phase
C. higher yields when cell growth slows
D. all of the above

A

D

72
Q

Fed batch reactors is used to produce vinegar because
A. it can maintain low ethanol concentrations
B. it can maintain low acetic acid concentrations
C. acetic acid bacteria tend to ferment at high ethanol
concentrations
D. all of the above

A

A

73
Q

When a culture of fermenting yeast becomes metabolically
uncoupled, ethanol
A. becomes a secondary metabolite
B. production becomes growth associated
C. production becomes non-growth associated
D. becomes a growth nutrient

A

C

74
Q

Mixing profiles closest to plug flow are observed in
A. continuous packed bed reactor
B. stirred tank reactor with biomass recycles
C. continuous fluidized bed bioreactor
D. all of these

A

A

75
Q

On a glucose medium, the growth of an organism is
characterized by the following Monod model and stoichiometric
parameters μm = 0.3 h-1, Ks =0.05 g.l-1 and Yxs = 0.3 g.g-1 When
this organism is grown in a 2 litre continuous on a medium
containing 10 g.l-1 of glucose added at 1 l.h-1, the steady state
concentration of biomass in the reactor will be
A. 0 g.l-1
B. 0.4 g.l-1
C. 0.5 g.l-1
D. 10 g.l-1

A

A

76
Q

Unsteady state mass balance for dynamic model of continuous
stirred tank reactor (CSTR) is
A. time rate of total amount in rector = rate of addition to
reactor -rate of removal + rate of formation
B. total amount in rector = rate of addition to reactor - rate
of removal + rate of formation
C. rate of total amount in rector = rate of addition to
reactor - rate of removal + rate of formation
D. none of the above

A

A

77
Q

A fed-batch reactor initially contains 2 litre of medium. If it was
fed at 1 litre per hour, then after 10 hours, the volume of the
reactor will be
A. 1 litre
B. 2 litre
C. 3 litre
D. 13 litre

A

B

78
Q

A Bacillus sp. produces an antibiotic only during the stationary
phase when grown in a batch culture. If grown in a 5 litre
continuous culture, the steady state productivity of the antibiotic
A. will increase until the culture washes out
B. will decrease after washout
C. will be zero
D. will be infinite

A

C

79
Q

In a fluidized bed reactor, the function of the disengagement
zone is to
A. reduce loss of particles from the reactor
B. reduce the velocity of the particles near the surface of
the reactor
C. reduce foaming problems
D. all of the above

A

D

80
Q

Two continuous bioreactors containing the same organisms, fed
with the same feed at the same dilution rate were compared.
Reactor 1 started with an initial concentration of glucose of 10
g.l-1, while reactor 2 contained 0.1 g.l-1 of glucose at the start of
the process then at steady state
A. the concentration of glucose in reactor 1 would be
greater than that in reactor 2
B. the concentration of glucose in reactor 1 would be
equal to reactor 2
C. the concentration of glucose in reactor 1 would always
be zero.
D. the concentration of glucose in reactor 1 would be less
than that in reactor 2

A

B

81
Q

In a plug flow reactor, the highest concentration of substrates is
exposed to the cells that
A. are near the effluent or exit of the reactor
B. are in the mid way along the reactor
C. are located near entrance of feed
D. are near the wall of the reactor

A

C

82
Q

In an activated sludge process, the biomass is recycled to
A. increase the efficiency of the process
B. reduce sludge volumes
C. increase the concentration of cells
D. all of the above

A

D

83
Q

Yeast is typically produced in fed batch reactors because
A. yeast cells produce ethanol at low glucose
concentrations
B. yeast cells ferment at low glucose concentrations
C. yeast cells respire at low glucose concentrations
D. all of the above

A

C

84
Q

Which of the following is not correct with regards to continuous
cultures?
A. The major industrial scale application of continuous
cultures is in waste water treatment
B. Mutation and contamination present a major risk to the
operation of continuous cultures for the production of
metabolites
C. The continuous cultures is very useful for the
production of pharmaceuticals
D. Continuous cultures have an advantage that they do
not need to shut down as regularly as batch culture
reactor

A

C

85
Q

Saccharomyces cerevisiae produces high biomass yields at low
glucose concentrations and high dissolved oxygen
concentrations. Which of the following should be followed for
maximizing its biomass productivity?
A. Batch fermenter with a high initial glucose
concentration
B. Continuous fermenter with a low initial glucose
concentration
C. Fed batch fermenter
D. All of the above

A

C

86
Q

In a glucose-yeast extract medium, Lactococcus lactis has a
maximum specific growth rate (um) of 1.23 h-1. What would be
the specific growth rate of this organism at steady state in a 4
litre reactor being fed at 2 litres per hour?
A. 0.5 h-1
B. 1.2 h-1
C. 2.4 h-1
D. 4 h-1

A

A

87
Q

A strain of Escherichia coli has a maximum specific growth rate
of 0.8 h-1 on a glucose based medium. If this organism is being
grown in a chemostat with a dilution rate of 1.2 h-1, then at
steady state the concentration of E. coli in the same medium will
A. increase
B. be zero
C. change randomly
D. decrease

A

B

88
Q

A fed-batch reactor containing 2 litre of medium and 0.1 g.l-l of
biomass is fed with a medium containing 1 g.l-1 of substrate at 1
litre per hour. If after 10 hours, the concentration of biomass in
the reactor was 0.2 g.l-1, then the biomass produced during the
10 hour period is
A. 1.5 g
B. 2.2 g
C. 3.0 g
D. 6.0 g

A

B

89
Q

Which of the following organisms will continue their metabolism
at high substrate concentrations?
A. Pseudomonas aeruginosa
B. Saccharomyces cerevisiae
C. Bacillus subtilis
D. Escherichia coli

A

A

90
Q

The concentration of biomass in a continuous stirred tank
reactor is 20 g dry weight per litre. What would be the
concentration of biomass in the effluent?
A. Greater than 20 g dry weight per litre
B. Approximately 20 g dry weight per litre
C. Lesser than 20 g dry weight per litre
D. More than 30 g dry weight per litre

A

B

91
Q

The production of an amylase from starch by Aspergillus niger is
often performed in a fed batch fermenter. This is due to the
reason that
A. fed-batch reactor can be used to minimize starch
concentrations and prevent a. niger from fermenting
B. fed-batch reactor can be used to minimize starch
concentrations and thus reduce the viscosity of the
medium
C. continuous reactor can be used to minimize starch
concentrations and their inhibitory effects
D. all of the above

A

B

92
Q

The fastest route of NADH reoxidation is
A. aerobic respiration
B. anaerobic respiration
C. fermentation
D. decomposition

A

C

93
Q

In a fluidized bed reactor mixing is achieved by
A. gravity flow of fluid
B. upward movement of the incoming feed
C. diffusion
D. both (a) and (b)

A

D

94
Q

In fed batch bioreactor modelling, the rate of change in the
bioreactor volume is assumed to be equal to
A. flow rate
B. initial volume
C. volume of solids in the reactor
D. none of these

A

A

95
Q

Monoclonal antibodies are typically produced in fed batch
reactors because
A. hybridoma cells ferment at high maltose concentrations
B. hybridoma cells yield higher lactate at high glucose
concentrations
C. hybridoma cells respire at high glucose concentrations
D. none of the above

A

B

96
Q

In plug flow tubular reactor the axial velocity profile on cross
section will be
A. constant
B. varying with time
C. non-linear
D. power function of time

A

A

97
Q

Production of organic acids in batch culture is generally growth
associated phase followed by non-growth associated
production. The probable reason for this is that
A. organic acids uncouple catabolism from anabolism
B. biomass yields increase as the fermentation proceeds
C. organic acids are secondary metabolites
D. high concentrations of organic acid promote the growth
of the microbial population

A

A

98
Q

The ideal tubular-flow fermenter without radial variations is
called a
A. plug flow fermenter
B. continuous stirred tank fermenter (CSTF)
C. column fermenter
D. any intensity of dilution rate near the wash out points

A

D

99
Q

Pseudo-steady state in a continuous reactor refers to a reactor
in which
A. Pseudomonads are being cultured
B. concentration oscillate around a mean value
C. concentration increase with time
D. concentration decrease with time

A

B

100
Q

The toxicity of organic acids to cells
A. enhances as the pH falls
B. reduces as the pH falls
C. is not affected by pH
D. is highest at pH 7.0

A

A

101
Q

Which of the following is best described as secondary
metabolite?
A. Acetic acid produced from the oxidation of ethanol
B. Ethanol from the fermentation of glucose
C. Penicillin
D. Citric acid from the partial oxidation of glucose

A

C

102
Q

A microorganism which is subjected to the Crabtree effect is
most likely to
A. ferment in the presence of low concentrations of sugar
and dissolved oxygen
B. respire in the presence of low sugar and high dissolved
oxygen concentrations
C. ferment in the presence of high concentrations of sugar
and dissolved oxygen
D. respire in the presence of high sugar and low dissolved
oxygen concentrations

A

C

103
Q

When the product formation is approximately equal to the rate of
cell growth, the pattern of product formation is termed as
A. uncoupled
B. growth associated
C. non-growth associated
D. metabolically uncoupled

A

B

104
Q

Which of the following would be correct concerning the
concentration of biomass (X). growth limiting substrate (S) and
product (P) in a chemostat when the cells have been washed
out?
A. X,S and P will be zero
B. X,S and P can not be predicted for the above condition
C. X and P will be zero while S is equal to the substrate
concentration in feed
D. None of the above

A

C

105
Q

Pseudomonas aeruginosa has a maximum specific growth rate
of 0.8 h-1 in a medium with glucose as a growth limiting
substrate. To prevent wash out, the dilution rate must be set to
A. greater than 0.8 h-1
B. less than 0.8 h-1
C. equal to 0.8 h-1
D. 1.6 h-1

A

B

106
Q

Saccharomyces cerevisiae when grown in high glucose
concentration medium, the cells activity depends on which of
the following?
A. High concentration of dissolved oxygen
B. Low concentration of dissolved oxygen
C. No effect of dissolved oxygen
D. High concentration of dissolved oxygen and sodium
salts

A

C

107
Q

Continuous culture has an advantage over to a batch cultures
as
A. continuous reactors do not need to be shut down and
cleaned as regularly as a batch reactor
B. most downstream and upstream processes are
continuous in nature and thus the operation of
continuous bioreactor can be better integrated into the
overall manufacturing process
C. cells can be maintained at a constant physiological
state simply by setting the dilution rate
D. all of the above

A

D

108
Q

In the batch-fed mode, substrate will be added
A. only at the beginning of the fermentation process
B. periodically throughout the fermentation process
C. only at the end of the fermentation process
D. substrate is never added

A

C

109
Q

When Escherichia coli grow in a well aerated medium, which of
the following will occur?
A. Fructose di-phosphate accumulation inside the cells
leading to cell respiration
B. Fructose di-phosphate accumulation inside the cells
leading to fermentation
C. Fructose di-phosphate will accumulate regardless of
the medium composition
D. Fructose di-phosphate will accumulate inside the cells
leading to anaerobic respiration

A

B

h trfs (13 decks)

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