Biochemical Reaction Engineering Mid - II, November - 2014

1.The overwhelming majority of industrial reactors are multiphase reactors. Most reactors contain
  • Solid phase (biomass aggregates or biomass immobilized on carrier material)
  • Liquid phase (water phase with pollutants / nutrient and products)
  • Gas phase (air or gas feed, gaseous products CO2, N2, CH4)
  • All of the above.
Answer: D
2.Depending on the location of the cell aggregates / immobilized cells and the movement of carrier material three reactor categories can be distinguished:
  • Mixed suspended particles (e.g. fluidized beds)
  • Fixed particles or large surfaces (e.g. packed beds, trickling filters)
  • Both a & b
  • None of the above.
Answer: C
3.Immobilization of biomass removes the washout limitation in continuous operation with
  • Free cells
  • Biological cells
  • Suspended cells
  • Electric cells
Answer: A
4.Cell recycling is, however, an alternative to cell immobilization that might be considered for operation at high cell densities, both in fed-batch and …………. also for removing the washout limitation
  • Continuous modes
  • Fixed cell
  • Suspended mode
  • Moving surfaces
Answer: A
5.Which flow in characteristic fashions, either dispersed in other phases or separately
  • Gases
  • Solids
  • Liquids
  • All of the above
Answer: D
6.In an ideal plug-flow or batch reactor, all the elements of material leaving the reactors have been inside them for exactly the same amount of time. The time reaction elements has spent in a reactor is called
  • Reaction time
  • Product time
  • Residence time
  • Non residence time
Answer: C
7.The model of CSTR with Bypassing and Dead Space can be used to describe this non-ideal flow existing inside a
  • Real bioreactor
  • Fluidised bed
  • Non real bioreactor
  • None of the above
Answer: A
8.Based on the ways of substrate addition, we can divide the bioreactors into
  • Batch
  • Continuous categories
  • Fed-batch
  • All of the above
Answer: D
9.Most fermentations outside of the food and beverage industry are carried out using
  • Pure cultures
  • Aseptic conditions
  • Both a & b
  • septic conditions
Answer: C
10.To prevent contamination during this operation, all of the vessels are needed to maintain positive air pressure. The simplest method is to pressurize the inoculum vessels using
  • Sterile air
  • Autoclave
  • Sterile water
  • Hot air oven
Answer: A
11.Design and operation of two-phase systems (liquid-solid) is considerably easier than_____________.
Answer: Three-phase reactors
12.Although for each type of immobilized cell system a variety of reactor types can be selected, optimal performance requires a careful matching of immobilization method and ___________________.
Answer: Reactor configuration
13.Cell recycling is, however, an alternative to cell immobilization that might be considered for operation at _________________.
Answer: High cell densities
14.The separation and recycling of cells can be achieved with the help of a ___________________.
Answer: Centrifugation/ settling or a membrane.
15.Flow patterns in these reactors are complex and phases rarely exhibit idealized _____________ or well-stirred flow behavior.
Answer: Plug-flow
16.__________model is mainly used to design medium continuous sterilization processes discussed previously or some enzyme catalytic reactions carriedout within tubular reactors.
Answer: The dispersion
17.Large bioreactors used for traditional fermentation industry, two parameter model ______________ and dead zone can be applied into these situations.
Answer: CSTR with bypassing
18.Bioreactors can also be classified according to the status of biomass within the reactors, that is, freely suspended or__________________
Answer: Or immobilized enzyme or cell bioreactors.
19.Typically, 3−5% of fermentations in an industrial plant are lost due to failure of_________________.
Answer: Sterilization procedures.
20.The gap between the rotating stirrer shaft and the fermenter bodies must be sealed properly. For small vessels_____________________ are preferential.
Answer: Magnetically driving stirrers