Fermentation Kinetics

Q1: 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-organisms is removed is called

A manostat

B chemostat

C turbidostat

D culturostat

Q2: 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

Q3: 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

Q4: 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

Q5: 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

Q6: The function of a mechanical seal is to

A prevent contaminants entering the reactor

B prevent cells from leaving the reactor

C both (a) and (b)

D prevent air to enter

Q7: 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

Q8: 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

Q9: The contents in jet loop reactor are mixed through

A compressed air

B a mechanical agitator

C external pumping

D any of these

Q10: 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

Q11: 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

Q12: The height to diameter ratio (H/D) for the column fermenters is

A <3

B >3

C <1.5

D >1.5

Q13: 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

Q14: Diauxie is

A growth factors

B microbiological die off

C the simultaneous uptake of nutrients

D the stagewise uptake of nutrients

Q15: 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

Q16: The maximum specific growth rate of an organism depends on

A medium composition

B temperature

C pH

D All of these

Q17: 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

Q18: Bacterial growth curve is obtained by plotting

A number of cells versus time

B number fo spores versus time

C log of number of cells versus time

D log of number of cells survived versus time

Q19: In an airlift bioreactor, the spent gases released from the liquid are called

A downcomer

B disengagement zone

C air riser

D flotsam

Q20: The maximum specific growth rate of an organism depends on

A medium composition

B temperature

C pH

D All of these

Q21: 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

Q22: 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

Q23: 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

Q24: Fermentor should be filled with medium upto

A 65-70%

B 70-75%

C 75-80%

D 80-85%

Q25: The phenomenon in which substrates are used in a sequential manner is known as

A trans-substrate genesis

B dialism

C diauxie

D multiplicity

Q26: 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

Q27: Why a T-flask used in small-scale cell culture is incubated in a horizontal position?

A To save space

B To increase the surface area of the liquid-air interface

C Both (a) and (b)

D To increase the rate of oxygen transfer into the liquid

Q28: 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

Q29: 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

Q30: 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

Q31: 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

Q32: The number of baffles in a standard stirred tank bioreactor is

A 8

B 6

C 4

D 2

Q33: 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

Q34: 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

Q35: Which of the following is correct for the prediction of time requirement in a batch fermenter?

A Carrying out experiments

B Mathematical modelling of the fermentation process

C Both (a) and (b)

D It is impossible to predict the time required for fermentation

Q36: 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

Q37: 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

Q38: 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

Q39: 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

Q40: 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


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