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  • Question
  • Mixing profiles closest to plug flow are observed in


  • Options
  • A. continuous packed bed reactor
  • B. stirred tank reactor with biomass recycles
  • C. continuous fluidized bed bioreactor
  • D. all of these

  • Correct Answer
  • continuous packed bed reactor 


  • Fermentation Reactors problems


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    • 1. For organisms growing in a chemostat, the specific growth rate

    • Options
    • A. cannot be determined
    • B. can be determined from the dilution rate
    • C. equals to the maximum specific growth rate of the culture
    • D. none of the above
    • Discuss
    • 2. When a culture of fermenting yeast becomes metabolically uncoupled, ethanol

    • Options
    • A. becomes a secondary metabolite
    • B. production becomes growth associated
    • C. production becomes non-growth associated
    • D. becomes a growth nutrient
    • Discuss
    • 3. The main reason for production of antibiotics in fed batch reactors is

    • Options
    • A. the presence of precursors is often toxic to the cells
    • B. higher yields when cells enter the stationary phase
    • C. higher yields when cell growth slows
    • D. all of the above
    • Discuss
    • 4. The lowest biomass yield in a culture of Escherichia coli will be in

    • Options
    • A. an aerated batch culture containing a initial high concentration of glucose
    • B. an aerated batch reactor containing an initial low concentration of glucose
    • C. an aerated fed-batch reactor having a low glucose concentration
    • D. an aerated continuous reactor having a low glucose concentration
    • Discuss
    • 5. In batch culture, protogon is produced from peptone during the stationary phase with a yield of 0.4 protogon mg per g of peptone. If it is to be produced in a chemostat at a dilution rate of 0.5 h-1 from a medium containing 10 g.l-1 of peptone, then the rate of protogon synthesis would be

    • Options
    • A. 0 g.l-1h-1
    • B. 0.5 g.l-1h-1
    • C. 1 g.l-1h-1
    • D. 2 g.l-1h-1
    • Discuss
    • 6. 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
    • 7. 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
    • 8. 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
    • 9. 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
    • 10. 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


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