29. A continuous reactor at steady state contains 0.04 g.l-1 of biomass and 0.02 g.l-1 of phenol. The feed contained 0.1 g.l-1 of phenol. The biomass yield would be
A.0.4 g.g-1
B.0.5 g.g-1
C.1.0 g.g-1
D.5.0 g.g-1

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30. A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.
A.continuous
B.batch
C.fed-batch
D.semi continuous

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31. The main reason for production of antibiotics in fed batch reactors is
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

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32. Fed batch reactors is used to produce vinegar because
A.it can maintain low ethanol concentrations
B.it can maintain low acetic acid concentrations
C.acetic acid bacteria tend to ferment at high ethanol concentrations
D.all of the above

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33. When a culture of fermenting yeast becomes metabolically uncoupled, ethanol
A.becomes a secondary metabolite
B.production becomes growth associated
C.production becomes non-growth associated
D.becomes a growth nutrient

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34. Mixing profiles closest to plug flow are observed in
A.continuous packed bed reactor
B.stirred tank reactor with biomass recycles
C.continuous fluidized bed bioreactor
D.all of these

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35. On a glucose medium, the growth of an organism is characterized by the following Monod model and stoichiometric parameters μm = 0.3 h-1, Ks =0.05 g.l-1 and Yxs = 0.3 g.g-1 When this organism is grown in a 2 litre continuous on a medium containing 10 g.l-1 of glucose added at 1 l.h-1, the steady state concentration of biomass in the reactor will be
A.0 g.l-1
B.0.4 g.l-1
C.0.5 g.l-1
D.10 g.l-1

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