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Fermentation Reactors Online Exam Quiz

Important questions about Fermentation Reactors. Fermentation Reactors MCQ questions with answers. Fermentation Reactors exam questions and answers for students and interviews.

1. Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is

Options

A : time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation

B : total amount in rector = rate of addition to reactor - rate of removal + rate of formation

C : rate of total amount in rector = rate of addition to reactor - rate of removal + rate of formation

D : none of the above

2. 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 -1 h -1

B : 0.5 g.l -1 h -1

C : 1 g.l -1 h -1

D : 2 g.l -1 h -1

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. When two populations compete for a single growth limiting substrate in a continuous fermenter, which organism would not be washed out?

Options

A : Organism maintaining the highest substrate concentration

B : Organism maintaining the lowest substrate concentration

C : Both (a) and (b)

D : Organism maintaining the moderate substrate concentration

10. In fed-batch fermentation, mass of substrate utilized is calculated using the relationship

Options

A : initial mass of substrate in the reactor + final mass of substrate in the reactor + flow rate x [substrate in the feed]

B : initial mass of substrate in the reactor - final mass of substrate in the reactor + flow rate x [substrate in the feed]

C : initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate x [substrate in the feed]

D : initial mass of substrate in the reactor + final mass of substrate in the reactor - flow rate

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