6. A fed-batch reactor containing 2 liters of medium and 0.1 g.l^-1 of biomass is fed with a medium containing 1 g.l1 of the substrate at 1 liter per hour. If after 10 hours, the concentration of biomass in the reactor was 0.2 g.l^-1, then the biomass produced during the 10 hour period is

A. 1.5 g
B. 2.2 g
C. 3.0 g
D. 6.0 g

7. Which of the following organisms will continue their metabolism at high substrate concentrations?

A. Pseudomonas aeruginosa
B. Saccharomyces cerevisiae
C. Bacillus subtilis
D. Escherichia coli

8. Yeast is typically produced in fed-batch reactors because

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

9. Two continuous bioreactors containing the same organisms, fed with the same feed at the same dilution rate were compared. Reactor 1 started with an initial concentration of glucose of 10 g.l^-1, while reactor 2 contained 0.1 g.l^-1 of glucose at the start of the process then at steady state

A. the concentration of glucose in reactor 1 would be greater than that in reactor 2
B. the concentration of glucose in reactor 1 would be equal to reactor 2
C. the concentration of glucose in reactor 1 would always be zero.
D. the concentration of glucose in reactor 1 would be less than that in reactor 2

10. In a fluidized bed reactor mixing is achieved by

A. gravity flow of fluid
B. upward movement of the incoming feed
C. diffusion
D. both (a) and (b)