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  • Question
  • A continuous reactor has a dilution rate of 0.5 h-1. Its residence time would be


  • Options
  • A. ln(2)/0.5
  • B. ln(2) x 0.5
  • C. 0.5 h
  • D. 2 h

  • Correct Answer
  • 2 h 


  • Fermentation Reactors problems


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    • 1. Mixing per unit volume is observed to be poorest in

    • Options
    • A. continuous packed bed reactor
    • B. continuous fluidized bed bioreactor
    • C. continuous airlift bioreactor
    • D. none of the above
    • Discuss
    • 2. A Bacillus sp. produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 litre continuous culture, the steady state productivity of the antibiotic

    • Options
    • A. will increase until the culture washes out
    • B. will decrease after washout
    • C. will be zero
    • D. will be infinite
    • Discuss
    • 3. Saccharomyces cerevisiae produces high biomass yields at low glucose concentrations and high dissolved oxygen concentrations. Which of the following should be followed for maximizing its biomass productivity?

    • Options
    • A. Batch fermenter with a high initial glucose concentration
    • B. Continuous fermenter with a low initial glucose concentration
    • C. Fed batch fermenter
    • D. All of the above
    • Discuss
    • 4. The continuous cultures are not widely used in industry because

    • Options
    • A. they are not suited for the production of secondary metabolites
    • B. contamination or mutation can have a disastrous effect on the operation
    • C. the government will not approve the licensing of pharmaceuticals produced in continuous cultures
    • D. all of the above
    • Discuss
    • 5. Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?

    • Options
    • A. NAD+ is diverted away from homeostasis to anabolism
    • B. ATP is diverted away from homeostasis to anabolism
    • C. NAD+ is diverted away from anabolism to homeostasis
    • D. ATP is diverted away from anabolism to homeostasis
    • Discuss
    • 6. Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because

    • Options
    • A. cells will redirect ATP to anabolism
    • B. cells will redirect NAD+ to anabolism
    • C. cells will redirect ATP to facilitate the diffusion of lactic acid and H+ out of the cells
    • D. cells will redirect ATP to the active transport of lactic acid and H+ out of the cells
    • Discuss
    • 7. Yield coefficient represents

    • Options
    • A. total biomass or product produced
    • B. conversion efficiency of a substrate into product
    • C. conversion rate of a substrate into biomass or product
    • D. production time of biomass or product
    • Discuss
    • 8. A continuous bioreactor in which only the flow rate is used to control the rate of cell or product productivity is called

    • Options
    • A. turbidostat
    • B. chemostat
    • C. level stat
    • D. pH
    • Discuss
    • 9. If biomass yields are constant, then the biomass productivity of a culture grown in continuous reactor will

    • Options
    • A. always decrease with dilution rate
    • B. increase with dilution rate until washout
    • C. remain constant irrespective of the dilution rate
    • D. decrease with dilution rate until washout
    • Discuss
    • 10. A fed-batch reactor initially contains 2 litre of medium. If it was fed at 1 litre per hour, then after 10 hours, the volume of the reactor will be

    • Options
    • A. 1 litre
    • B. 2 litre
    • C. 3 litre
    • D. 13 litre
    • Discuss


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