Question is ⇒ The function of the disengagement zone in an airlift fermenter is to, Options are ⇒ (A) prevent CO<sub>2</sub> rich bubbles from entering the downcomer, (B) reduce the velocity of the bubbles, (C) reduce liquid loss as aerosols, (D) all of the above, (E) , Leave your comments or Download question paper.

Question is ⇒ The function of the disengagement zone in an airlift fermenter is to, Options are ⇒ (A) prevent CO<sub>2</sub> rich bubbles from entering the downcomer, (B) reduce the velocity of the bubbles, (C) reduce liquid loss as aerosols, (D) all of the above, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	The function of the disengagement zone in an airlift fermenter is to
A.	prevent CO₂ rich bubbles from entering the downcomer [Wrong Answer]
B.	reduce the velocity of the bubbles [Wrong Answer]
C.	reduce liquid loss as aerosols [Wrong Answer]
D.	all of the above [Correct Answer]
View Answer 1 -1 Explanation:- Answer : D Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ If the specific growth rate, μ. is constant with time during the exponential growth period, the equation correlating bacterial number density C_n), cell number concentration with respect to time can be expressed as
C_n= C_n₀ exp[μ (t - t₀)]
C_n₀ = C_n exp[μ (t - t₀)]
C_n/C_n₀ =(1/μ)exp(t-t₀)
C_n₀ / C_n = (1/μ)exp(t-t₀)

⇒ During the log phase cell numbers increase exponentially
because cells produce enzymes
because cells do not have cell membranes
because cells are autocatalysts
because the rate of cell division increases exponentially

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

⇒ In an airlift bioreactor, the air sparging region is called
downcomer
disengagement zone
air riser
none of these

⇒ The specific growth rate is affected by
sabstrate concentration
product concentration
oxygen supply
all of these

⇒ In a batch reactor specific growth rate
remains constant throughout the process
increases exponentially
changes during the fermentation
is highest during the stationary phase

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

⇒ Population doubling time, t_d can be expressed as (where μ is the specific growth rate.)
log2/μ
ln2/μ
μ/ln2
μ/log2

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

⇒ In the accelerated phase, cell starts to
increase and the division rate increases to reach a maximum
decrease and the division rate increases to reach a maximum
increase and the division rate decreases to reach a maximum
increase and the division rate increases to reach a minimum

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

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

⇒ The diameter of the baffles in a standard stirred tank bioreactor ranges from
1/10^th - 1/12^th of the tank diameter
1/3^rd - 1/4^thof the tank diameter
1/15^th - 1/20^th of the tank diameter
1/20^th - 1/25^th of the tank diameter

⇒ The Monod Model relates
substrate utilized with the biomass consumption
specific growth rate to the substrate availability
yield with the biomass utilization
the biomass concentration with specific growth rate

⇒ The dilution rate, D is defined as(where F = volumetric flow rate, V_R = total volume of culture in the reactor and μ specific growth rate)
F/V_R
V_R/F
μ/F
F/μ

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

⇒ 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.
continuous
batch
fed-batch
semi continuous

⇒ The high oxygen transfer efficiencies of airlift bioreactors is due to
the large aspect ratio of the reactor, which leads to a high gas hold-up
the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
the draft tube, which reduces bubble coalescence in the reactor
all of the above

⇒ Wash out in steady state fermentation occurs when
dilution rate is less than maximum specific growth rate
dilution rate is higher than the maximum specific growth rate
cell concentration reaches the maximum
specific growth rate is maximum

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

⇒ An internal draft tube is preferrred to an external draft tube because
it is easier to clean and sterilize a reactor
it is cheaper to build a reactor with an internal draft tube
Both (a) and (b)
none of the above

⇒ 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
lag phase
stationary phase
death phase
exponential growth phase

⇒ Chemostats work on the principle of
maintaining constant volume of culture medium
maintaining continuous flow of nutrients
maintaining uniform nutrients concentration
operating at higher pressure

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

⇒ Heat transfer rates (per unit volume) will be lowest in
Stirred tank bioreactor with biomass recycle
Continuous air lift bioreactor
Continuous packed bed reactor
Continuous fluidized bed bioreactor

⇒ Bacterial growth curve is obtained by plotting
number of cells versus time
number fo spores versus time
log of number of cells versus time
log of number of cells survived versus time

⇒ Which of the following is correct for the prediction of time requirement in a batch fermenter?
Carrying out experiments
Mathematical modelling of the fermentation process
Both (a) and (b)
It is impossible to predict the time required for fermentation

⇒ Tower fermentors are used for
continuous penicillin production
continuous beer production
production of enzymes
batch production of beer

⇒ Stationary phase is described as
no further increase in the cell population after a maximum value
deceleration of growth and division rate after the growth rate reaches a maximum
acceleration of growth and division rate after the growth rate reaches a maximum
deceleration of growth and division rate after the growth rate reaches a minimum

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