16. 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

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

17. The concentration of biomass in a continuous stirred tank reactor is 20 g dry weight per liter. What would be the concentration of biomass in the effluent?

A. Greater than 20 g dry weight per liter
B. Approximately 20 g dry weight per liter
C. Lesser than 20 g dry weight per liter
D. More than 30 g dry weight per liter

18. The ideal tubular-flow fermenter without radial variations is called a

A. plug flow fermenter
B. continuous stirred tank fermenter (CSTF)
C. column fermenter
D. any intensity of dilution rate near the washout points

19. Pseudo-steady state in a continuous reactor refers to a reactor in which

A. Pseudomonads are being cultured
B. concentration oscillate around a mean value
C. concentration increase with time
D. concentration decrease with time

20. The toxicity of organic acids to cells

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