Fermentation Kinetics Questions and Answers

Multiple Choice Questions (MCQ) and Answers on Fermentation Kinetics

Question 1: A higher Ks value of Monod’s equation means

  1. greater affinities to substrate
  2. lower affinities to substrate
  3. unaffected with the substrate bonding
  4. 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

  1. decreases the productivity of the fermenter
  2. increases the productivity of the fermenter
  3. modestly increases the productivity of the fermenter
  4. does not affect on the productivity

Answer: 1

Question 3: Heat transfer rates (per unit volume) will be lowest in

  1. Stirred tank bioreactor with biomass recycle
  2. Continuous air lift bioreactor
  3. Continuous packed bed reactor
  4. Continuous fluidized bed bioreactor

Answer: 3

Question 4: The function(s) of the draft tube in an airlift bioreactor is

  1. to reduce bubble coalescence
  2. to improve circulation
  3. to even out shear conditions throughout the reactor
  4. all of the above

Answer: 4

Question 5: The Monod Model relates

  1. substrate utilized with the biomass consumption
  2. specific growth rate to the substrate availability
  3. yield with the biomass utilization
  4. the biomass concentration with specific growth rate

Answer: 2

Question 6: The height to diameter ratio (H/D) for the column fermenters is

  1. <3
  2. >3
  3. <15
  4. >15

Answer: 2

Question 7: The high oxygen transfer efficiencies of airlift bioreactors is due to

  1. the large aspect ratio of the reactor, which leads to a high gas hold-up
  2. the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
  3. the draft tube, which reduces bubble coalescence in the reactor
  4. all of the above

Answer: 4

Question 8: The function of a mechanical seal is to

  1. prevent contaminants entering the reactor
  2. prevent cells from leaving the reactor
  3. both (a) and (b)
  4. prevent air to enter

Answer: 3

Question 9: The phenomenon in which substrates are used in a sequential manner is known as

  1. trans-substrate genesis
  2. dialism
  3. diauxie
  4. 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)

  1. F/VR
  2. VR/F
  3. μ/F
  4. F/μ

Answer: 1

Question 11: Why a T-flask used in small-scale cell culture is incubated in a horizontal position?

  1. To save space
  2. To increase the surface area of the liquid-air interface
  3. Both (a) and (b)
  4. To increase the rate of oxygen transfer into the liquid

Answer: 3

Question 12: Bubble column reactor has

  1. large height to diameter ratio
  2. small height to diameter ratio
  3. large diameter to height ratio
  4. small diameter to height ratio

Answer: 1

Question 13: In the death phase

  1. nutrients available for the cells are depleted and begin to die
  2. the number of viable cells will increase
  3. nutrients available for cells are replenished and start to multiply
  4. none of the above

Answer: 1

Question 14: The maximum specific growth rate of an organism depends on

  1. medium composition
  2. temperature
  3. pH
  4. All of these

Answer: 4

Question 15: Which of the following is not correct for the Monod model and the Michaelis Menten Model?

  1. The Michaelis Menten Model was derived from a curve fitting exercise
  2. The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
  3. The Monod model was derived from an analysis of the mechanism of microbial growth
  4. 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.

  1. permeabilize
  2. lyophilize
  3. heat-kill
  4. denature

Answer: 1

Question 17: Bacterial growth curve is obtained by plotting

  1. number of cells versus time
  2. number of spores versus time
  3. log of number of cells versus time
  4. 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

  1. manostat
  2. chemostat
  3. turbidostat
  4. culturostat

Answer: 3

Question 19: Wash out in steady state fermentation occurs when

  1. dilution rate is less than maximum specific growth rate
  2. dilution rate is higher than the maximum specific growth rate
  3. cell concentration reaches the maximum
  4. specific growth rate is maximum

Answer: 2

Question 20: Fermentor should be filled with medium upto

  1. 65-70%
  2. 70-75%
  3. 75-80%
  4. 80-85%

Answer: 3

Question 21: In the stationary phase

  1. growth is proportional to death
  2. growth rate is equal to death rate
  3. growth rate is lesser than death rate
  4. 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?

  1. Volume of cuboid = length x breadth x height
  2. The Monod Model
  3. The Michaelis Menten Equation
  4. All of the above

Answer: 4

Question 23: Biomass concentrations during fermentation is

  1. diluting the samples to optical density less than 0.3
  2. monitored by controlling the changes in biomass concentrations
  3. considering that optical density is proportional to the surface area of the biomass in the sample
  4. all of the above

Answer: 4

Question 24: Chemostats work on the principle of

  1. maintaining constant volume of culture medium
  2. maintaining continuous flow of nutrients
  3. maintaining uniform nutrients concentration
  4. operating at higher pressure

Answer: 3

Question 25: During the exponential phase the maximum specific growth rate equals specific growth rate as

  1. concentration of the growth limiting substrate is much less than the monod constant
  2. concentration of growth limiting substrate is much greater than the monod constant
  3. specific growth rate increases exponentially
  4. 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?

  1. Carrying out experiments
  2. Mathematical modelling of the fermentation process
  3. Both (a) and (b)
  4. 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

  1. downcomer
  2. disengagement zone
  3. air riser
  4. flotsam

Answer: 2

Question 28: The contents in jet loop reactor are mixed through

  1. compressed air
  2. a mechanical agitator
  3. external pumping
  4. any of these

Answer: 3

Question 29: The specific growth rate (μ) is defined as

  1. the concentration of biomass in the reactor
  2. rate of increase of total biomass in a reactor
  3. the rate of individual cells division or increase in their biomass
  4. the rate of cell death

Answer: 3

Question 30: The number of baffles in a standard stirred tank bioreactor is

  1. 8
  2. 6
  3. 4
  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

  1. In [biomass] against time for exponential phase data only
  2. In [biomass] against time
  3. biomass against time
  4. 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

  1. downcomer
  2. disengagement zone
  3. air riser
  4. flotsam

Answer: 1

Question 33: Population doubling time, td can be expressed as (where μ is the specific growth rate)

  1. log2/μ
  2. ln2/μ
  3. μ/ln2
  4. μ/log2

Answer: 2

Question 34: The function of the disengagement zone in an airlift fermenter is to

  1. prevent CO2 rich bubbles from entering the downcomer
  2. reduce the velocity of the bubbles
  3. reduce liquid loss as aerosols
  4. all of the above

Answer: 4

Question 35: A mixed fermentation is one, which produces

  1. both alcohol and carbon dioxide
  2. both acid and carbon dioxide
  3. both acid and alcohol
  4. several different kinds of acid

Answer: 3

Question 36: The monod model predicts that the specific growth rate

  1. will increase with the concentration of the growth limiting substrate until it reaches a maximum value
  2. will decrease with the concentration of the growth limiting substrate
  3. will increase with the concentration of the growth limiting substrate
  4. does not depend on growth limiting substrate

Answer: 1

Question 37: In the accelerated phase, cell starts to

  1. increase and the division rate increases to reach a maximum
  2. decrease and the division rate increases to reach a maximum
  3. increase and the division rate decreases to reach a maximum
  4. increase and the division rate increases to reach a minimum

Answer: 1

Question 38: Stationary phase is described as

  1. no further increase in the cell population after a maximum value
  2. deceleration of growth and division rate after the growth rate reaches a maximum
  3. acceleration of growth and division rate after the growth rate reaches a maximum
  4. 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

  1. manostat
  2. chemostat
  3. turbidostat
  4. culturostat

Answer: 2

Question 40: Diauxie is

  1. growth factors
  2. microbiological die off
  3. the simultaneous uptake of nutrients
  4. the stagewise uptake of nutrients

Answer: 4