Multiple Choice Questions (MCQ) and Answers on Fermentation Kinetics
Question 1: A higher Ks value of Monod’s equation means
- greater affinities to substrate
- lower affinities to substrate
- unaffected with the substrate bonding
- lower dissociation constant value
Answer: 1
Question 2: 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
Answer: 1
Question 3: 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
Answer: 3
Question 4: 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
Answer: 4
Question 5: 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
Answer: 2
Question 6: The height to diameter ratio (H/D) for the column fermenters is
- <3
- >3
- <15
- >15
Answer: 2
Question 7: 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
Answer: 4
Question 8: The function of a mechanical seal is to
- prevent contaminants entering the reactor
- prevent cells from leaving the reactor
- both (a) and (b)
- prevent air to enter
Answer: 3
Question 9: The phenomenon in which substrates are used in a sequential manner is known as
- trans-substrate genesis
- dialism
- diauxie
- multiplicity
Answer: 3
Question 10: 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)
- F/VR
- VR/F
- μ/F
- F/μ
Answer: 1
Question 11: Why a T-flask used in small-scale cell culture is incubated in a horizontal position?
- To save space
- To increase the surface area of the liquid-air interface
- Both (a) and (b)
- To increase the rate of oxygen transfer into the liquid
Answer: 3
Question 12: Bubble column reactor has
- large height to diameter ratio
- small height to diameter ratio
- large diameter to height ratio
- small diameter to height ratio
Answer: 1
Question 13: In the death phase
- nutrients available for the cells are depleted and begin to die
- the number of viable cells will increase
- nutrients available for cells are replenished and start to multiply
- none of the above
Answer: 1
Question 14: The maximum specific growth rate of an organism depends on
- medium composition
- temperature
- pH
- All of these
Answer: 4
Question 15: Which of the following is not correct for the Monod model and the Michaelis Menten Model?
- The Michaelis Menten Model was derived from a curve fitting exercise
- The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
- The Monod model was derived from an analysis of the mechanism of microbial growth
- All of the above
Answer: 3
Question 16: 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
Answer: 1
Question 17: Bacterial growth curve is obtained by plotting
- number of cells versus time
- number of spores versus time
- log of number of cells versus time
- log of number of cells survived versus time
Answer: 3
Question 18: 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
Answer: 3
Question 19: 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
Answer: 2
Question 20: Fermentor should be filled with medium upto
- 65-70%
- 70-75%
- 75-80%
- 80-85%
Answer: 3
Question 21: In the stationary phase
- growth is proportional to death
- growth rate is equal to death rate
- growth rate is lesser than death rate
- no co-relation exist between death rate and growth rate
Answer: 2
Question 22: 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
Answer: 4
Question 23: Biomass concentrations during fermentation is
- diluting the samples to optical density less than 0.3
- monitored by controlling the changes in biomass concentrations
- considering that optical density is proportional to the surface area of the biomass in the sample
- all of the above
Answer: 4
Question 24: 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
Answer: 3
Question 25: During the exponential phase the maximum specific growth rate equals specific growth rate as
- concentration of the growth limiting substrate is much less than the monod constant
- concentration of growth limiting substrate is much greater than the monod constant
- specific growth rate increases exponentially
- concentration of the growth limiting substrate is equal to the monod constant
Answer: 2
Question 26: 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
Answer: 3
Question 27: In an airlift bioreactor, the spent gases released from the liquid are called
- downcomer
- disengagement zone
- air riser
- flotsam
Answer: 2
Question 28: The contents in jet loop reactor are mixed through
- compressed air
- a mechanical agitator
- external pumping
- any of these
Answer: 3
Question 29: 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
Answer: 3
Question 30: The number of baffles in a standard stirred tank bioreactor is
- 8
- 6
- 4
- 2
Answer: 3
Question 31: The maximum specific growth rate (μm) 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
Answer: 1
Question 32: The region of an airlift bioreactor in which the liquid travels in a downward direction is called the
- downcomer
- disengagement zone
- air riser
- flotsam
Answer: 1
Question 33: Population doubling time, td can be expressed as (where μ is the specific growth rate)
- log2/μ
- ln2/μ
- μ/ln2
- μ/log2
Answer: 2
Question 34: 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
Answer: 4
Question 35: A mixed fermentation is one, which produces
- both alcohol and carbon dioxide
- both acid and carbon dioxide
- both acid and alcohol
- several different kinds of acid
Answer: 3
Question 36: 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
Answer: 1
Question 37: 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
Answer: 1
Question 38: 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
Answer: 1
Question 39: 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
- manostat
- chemostat
- turbidostat
- culturostat
Answer: 2
Question 40: Diauxie is
- growth factors
- microbiological die off
- the simultaneous uptake of nutrients
- the stagewise uptake of nutrients
Answer: 4