Question is ⇒ In the death phase, Options are ⇒ (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, (E) , Leave your comments or Download question paper.

Question is ⇒ In the death phase, Options are ⇒ (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, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	In the death phase
A.	nutrients available for the cells are depleted and begin to die [Correct Answer]
B.	the number of viable cells will increase [Wrong Answer]
C.	nutrients available for cells are replenished and start to multiply [Wrong Answer]
D.	none of the above [Wrong Answer]
View Answer 1 -1 Explanation:- Answer : A 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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⇒ 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

⇒ 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

⇒ 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 function of the disengagement zone in an airlift fermenter is to
prevent CO₂ rich bubbles from entering the downcomer
reduce the velocity of the bubbles
reduce liquid loss as aerosols
all of the above

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

⇒ Concentration of the growth limiting substrate means
trace elements concentration
the concentration of the substrate that controls the growth rate of the cells
sugar concentration in the fermentation medium
dissolved oxygen concentration

⇒ 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

⇒ The contents in jet loop reactor are mixed through
compressed air
a mechanical agitator
external pumping
any of these

⇒ 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 maximum specific growth rate (μ_m) of an organism in batch culture is equal to slope of a plot of
In [biomass] against time for exponential phase data only
In [biomass] against time
biomass against time
biomass against time for stationary phase data only

⇒ 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

⇒ The monod model predicts that the specific growth rate
will increase with the concentration of the growth limiting substrate until it reaches a maximum value
will decrease with the concentration of the growth limiting substrate
will increase with the concentration of the growth limiting substrate
does not depend on growth limiting substrate

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

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

⇒ 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

⇒ The region of an airlift bioreactor in which the liquid travels in a downward direction is called the
downcomer
disengagement zone
air riser
flotsam

⇒ 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

⇒ Fermentor should be filled with medium upto
65-70%
70-75%
75-80%
80-85%

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

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

⇒ The number of baffles in a standard stirred tank bioreactor is
8
6
4
2

⇒ 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

⇒ When intracellular enzymes of whole cells are to be used in a bio-conversion process, it is often necessary to____________the cells.
permeabilize
lyophilize
heat-kill
denature

⇒ 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

⇒ 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
manostat
chemostat
turbidostat
culturostat

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

⇒ 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

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

⇒ The function(s) of the draft tube in an airlift bioreactor is
to reduce bubble coalescence
to improve circulation
to even out shear conditions throughout the reactor
all of the above

⇒ 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