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  • Question
  • Yeast is typically produced in fed batch reactors because


  • Options
  • A. yeast cells produce ethanol at low glucose concentrations
  • B. yeast cells ferment at low glucose concentrations
  • C. yeast cells respire at low glucose concentrations
  • D. all of the above

  • Correct Answer
  • yeast cells respire at low glucose concentrations 


  • Fermentation Reactors problems


    Search Results


    • 1. Continuous culture has an advantage over to a batch cultures as

    • Options
    • A. continuous reactors do not need to be shut down and cleaned as regularly as a batch reactor
    • B. most downstream and upstream processes are continuous in nature and thus the operation of continuous bioreactor can be better integrated into the overall manufacturing process
    • C. cells can be maintained at a constant physiological state simply by setting the dilution rate
    • D. all of the above
    • Discuss
    • 2. In an activated sludge process, the biomass is recycled to

    • Options
    • A. increase the efficiency of the process
    • B. reduce sludge volumes
    • C. increase the concentration of cells
    • D. all of the above
    • Discuss
    • 3. Production of organic acids in batch culture is generally growth associated phase followed by non-growth associated production. The probable reason for this is that

    • Options
    • A. organic acids uncouple catabolism from anabolism
    • B. biomass yields increase as the fermentation proceeds
    • C. organic acids are secondary metabolites
    • D. high concentrations of organic acid promote the growth of the microbial population
    • Discuss
    • 4. A microorganism which is subjected to the Crabtree effect is most likely to

    • Options
    • A. ferment in the presence of low concentrations of sugar and dissolved oxygen
    • B. respire in the presence of low sugar and high dissolved oxygen concentrations
    • C. ferment in the presence of high concentrations of sugar and dissolved oxygen
    • D. respire in the presence of high sugar and low dissolved oxygen concentrations
    • Discuss
    • 5. The toxicity of organic acids to cells

    • Options
    • A. enhances as the pH falls
    • B. reduces as the pH falls
    • C. is not affected by pH
    • D. is highest at pH 7.0
    • Discuss
    • 6. Monoclonal antibodies are typically produced in fed batch reactors because

    • Options
    • A. hybridoma cells ferment at high maltose concentrations
    • B. hybridoma cells yield higher lactate at high glucose concentrations
    • C. hybridoma cells respire at high glucose concentrations
    • D. none of the above
    • Discuss
    • 7. Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems when

    • Options
    • A. baffled systems are used
    • B. Reynolds number is less than 300
    • C. both (a)and(b)
    • D. none of these
    • Discuss
    • 8. Larger propellers turn at the speed of

    • Options
    • A. 20 to 150 rpm
    • B. 150 to 300 rpm
    • C. 400 to 800 rpm
    • D. 1150 rpm
    • Discuss
    • 9. What is/are the major difference(s) between disc and turbine type stirrer?

    • Options
    • A. Blades in disc type are projected out beyond the edge of disc while blades are curved one in turbine type
    • B. Turbine type requires 50 % less air than disc type for the same yield and energy consumption
    • C. Both (a) and (b)
    • D. Number of blades in the stirrer
    • Discuss
    • 10. In the bubble boundary layer, oxygen concentration can be determined by measuring

    • Options
    • A. the steady state oxygen concentration in a mixed aerated reactor before inoculation
    • B. the steady state oxygen concentration in a mixed aerated reactor after inoculation
    • C. the steady state oxygen concentration in the boundary layer using a micro-probe
    • D. volume of oxygen supplied
    • Discuss


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