Fermentation Kinetics Flashcards by Cathrina Chavez

The function of the disengagement zone in an
airlift fermenter is to

a. prevent CO2 rich bubbles from entering the
downcomer
b. reduce the velocity of the bubbles
c. reduce liquid loss as aerosols
d. all of the above

d. all of the above

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Stationary phase is described as

a. no further increase in the cell population
after a maximum value

b. deceleration of growth and division rate
after the growth rate reaches a maximum

c. acceleration of growth and division rate
after the growth rate reaches a maximum

d. deceleration of growth and division rate
after the growth rate reaches a minimum

a. no further increase in the cell population
after a maximum value

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In the accelerated phase, cell starts to

a. increase and the division rate increases to
reach a maximum

b. decrease and the division rate increases to
reach a maximum

c. increase and the division rate decreases to
reach a maximum

d. increase and the division rate increases to
reach a minimum

a. increase and the division rate increases to
reach a maximum

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A mixed fermentation is one, which produces

a. both alcohol and carbon dioxide
b. both acid and carbon dioxide
c. both acid and alcohol
d. several different kinds of acid

c. both acid and alcohol

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The Monod model predicts that the specific
growth rate

a. will increase with the concentration of the
growth limiting substrate until it reaches a
maximum value

b. will decrease with the concentration of the
growth limiting substrate

c. will increase with the concentration of the
growth limiting substrate

d. does not depend on growth limiting
substrate

a. will increase with the concentration of the
growth limiting substrate until it reaches a
maximum value

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The phenomenon in which substrates are used
in a sequential manner is known as
a. trans-substrate genesis
b. dialism
c. diauxie
d. multiplicity

c. diauxie

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The dilution rate, D is defined as (where F =
volumetric flow rate, VR = total volume of
culture in the reactor and μ specific growth rate)
a. F/VR
b. VR/F
c. μ/F
d. F/μ

a. F/VR

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Diauxie is
a. growth factors
b. microbiological die off
c. the simultaneous uptake of nutrients
d. the stagewise uptake of nutrients

d. the stagewise uptake of nutrients

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An open system in which the growth rate is
maintained by adding a nutrient (present in
limiting quantities) at the same rate as that
medium containing micro-organism is removed
is called

a. Manostat
b. Chemostat
c. Turbidostat
d. Culturostat

b. Chemostat

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In the death phase
a. nutrients available for the cells are depleted
and begin to die
b. the number of viable cells will increase
c. nutrients available for cells are replenished
and start to multiply
d. none of the above

a. nutrients available for the cells are depleted
and begin to die

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The maximum specific growth rate of an
organism depends on
a. medium composition
b. temperature
c. pH
d. All of these

d. All of these

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Which of the following is not correct for the
Monod model and the Michaelis Menten Model

a. The Michaelis Menten Model was derived
from a curve fitting exercise

b. The Michaelis Menten model was derived
from an analysis of the mechanism of
microbial growth

c. The Monod model was derived from an
analysis of the mechanism of microbial
growth

d. All of the above

c. The Monod model was derived from an
analysis of the mechanism of microbial
growth

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Bubble column reactor has
a. large height to diameter ratio
b. small height to diameter ratio
c. large diameter to height ratio
d. small diameter to height ratio

a. large height to diameter ratio

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An open system in which the growth rate is
maintained by the removal and addition of
media at such a rate as to maintain a constant
cell density is called a

a. Manostat
b. Chemostat
c. Turbidostat
d. Culturostat

c. Turbidostat

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Wash out in steady state fermentation occurs
when

a. dilution rate is less than maximum specific
growth rate

b. dilution rate is higher than the maximum
specific growth rate

c. cell concentration reaches the maximum

d. specific growth rate is maximum

b. dilution rate is higher than the maximum
specific growth rate

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Fermenter should be filled with medium upto
a. 65-70%
b. 70-75%
c. 75-80%
d. 80-85%

c. 75-80%

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Bacterial growth curve is obtained by plotting
a. number of cells versus time
b. number of spores versus time
c. log of number of cells versus time
d. log of number of cells survived versus time

c. log of number of cells versus time

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When intracellular enzymes of whole cells are
to be used in a bio-conversion process, it is
often necessary to____________the cells.

a. Permeabilize
b. Lyophilize
c. heat-kill
d. denature

a. Permeabilize

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Heat transfer rates (per unit volume) will be
lowest in

a. Stirred tank bioreactor with biomass
recycle
b. Continuous air lift bioreactor
c. Continuous packed bed reactor
d. Continuous fluidized bed bioreactor

c. Continuous packed bed reactor

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The function(s) of the draft tube in an airlift
bioreactor is

a. to reduce bubble coalescence
b. to improve circulation
c. to even out shear conditions throughout the
reactor
d. all of the above

d. all of the above

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The Monod Model relates

a. substrate utilized with the biomass
consumption

b. specific growth rate to the substrate
availability

c. yield with the biomass utilization

d. the biomass concentration with specific
growth rate

b. specific growth rate to the substrate
availability

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The height to diameter ratio (H/D) for the
column fermenters is
a. <3
b. >3
c. <1.5
d. >1.5

b. >3

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The high oxygen transfer efficiencies of airlift
bioreactors is due to

a. the large aspect ratio of the reactor, which
leads to a high gas hold-up

b. the large aspect ratio of the reactor, which
leads to a high oxygen solubility at the base
of the reactor

c. the draft tube, which reduces bubble
coalescence in the reactor

d. all of the above

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The maximum specific growth rate (μm) of an
organism in batch culture is equal to slope of a plot of

a. In [biomass] against time for exponential
phase data only

b. In [biomass] against time

c. biomass against time

d. biomass against time for stationary phase
data only

a. In [biomass] against time for exponential
phase data only

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The region of an airlift bioreactor in which the liquid travels in a downward direction is called the a. Downcomer b. disengagement zone c. air riser d. flotsam

a. Downcomer

Population doubling time, td can be expressed as (where μ is the specific growth rate.) a. log2/μ b. ln2/μ c. μ/ln2 d. μ/log2

b. ln2/μ

A higher Ks value of Monod's equation means a. greater affinities to substrate b. lower affinities to substrate c. unaffected with the substrate bonding d. lower dissociation constant value

a. greater affinities to substrate

The increased air flow rate in bubble column fermenter can cause excessive foaming and high retention of air bubbles in the column which a. decreases the productivity of the fermenter b. increases the productivity of the fermenter c. modestly increases the productivity of the fermenter d. does not affect on the productivity

a. decreases the productivity of the fermenter

In an airlift bioreactor, the spent gases released from the liquid are called a. Downcomer b. disengagement zone c. air riser d. flotsam

b. disengagement zone

The contents in jet loop reactor are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these

c. external pumping

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

c. the rate of individual cells division or increase in their biomass

The number of baffles in a standard stirred tank bioreactor is a. 8 b. 6 c. 4 d. 2

c. 4

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

b. growth rate is equal to death rate

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

d. All of the above

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

d. all of the above

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

c. maintaining uniform nutrients concentration

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

b. concentration of growth limiting substrate is much greater than the Monod constant

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

c. 1942

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. cells tend to grow without dividing leading to a decrease in the surface area to volume ratio

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

d. all of the above

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. micro mixing

A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a ________ culture. a. Continuous b. Batch c. fed-batch d. semi continuous

b. Batch

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. Cn= Cn0 exp [μ (t - t0)]

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. 1/10th - 1/12th of the tank diameter

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 auto catalysts d. because the rate of cell division increases exponentially

c. because cells are auto catalysts

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

c. substrate disliking

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

c. changes during the fermentation

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. high dilution rates near the washout point

The specific growth rate is affected by a. substrate concentration b. product concentration c. oxygen supply d. all of these

d. all of these

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 minimize bubble coalescence c. concentrate shear forces around the sparger d. concentrate shear forces near the disengagement zone

b. distribute shear forces throughout the reactor and minimize bubble coalescence

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

c. STF can't be used for high viscosity medium

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. compressed air

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

d. All of the above

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

b. cells synthesize new proteins and membrane components

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

b. the concentration of the substrate that controls the growth rate of the cells

Tower fermenters are used for a. continuous penicillin production b. continuous beer production c. production of enzymes d. batch production of beer

b. continuous beer production

In wastewater treatment, which bioreactor is generally used? a. Plug flow reactor b. Trickle bed reactor c. Tower fermenter d. CSTR

b. Trickle bed reactor

The contents in stirred tank rector are mixed through a. compressed air b. a mechanical agitator c. external pumping d. any of these

b. a mechanical agitator

The height to diameter ratio (H/D) for the tank fermenters is a. < 3 b. > 3 c. < 1.5 d. > 1.5

a. < 3

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

c. decrease the overall fermentation time

In an airlift bioreactor, the air sparging region is called a. Downcomer b. disengagement zone c. air riser d. none of these

c. air riser

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

c. better heat transfer efficiencies

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. lag phase

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

b. It does not consider factors that causes cells growth to stop or slow

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

b. Flotsam, jetsam, downzone