Biochem - Fermentation Reactors [S1]

Question 1

1. Yield coefficient represents

Answer 1

1. Conversion efficiency of a substrate into product

Question 2

2. The lowest biomass yield in a culture of Escherichia coli will be in

Answer 2

2. An aerated batch culture containing an initial high concentration of glucose

Question 3

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

Answer 3

3. Organism maintaining the lowest substrate concentration

Question 4

4. The continuous cultures are not widely used in industry because

Answer 4

4. All of the above

Question 5

5. The lowest yield of ATP is in

Answer 5

5. Fermentation

Question 6

6. Mixing in an anaerobic sludge blanket reactor is due to

Answer 6

6. Release of gases by the microbial populations

Question 7

7. 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−1−1from a medium containing 10 g/L of peptone, then the rate of protogon synthesis would be

Answer 7

7. 2 g/L-h

Question 8

8. Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because

Answer 8

8. Cells will redirect ATP to the active transport of lactic acid and H+ out of the cells

Question 9

9. Which of the following would not be subjected to the “glucose effect”?

Answer 9

9. Aspergillus fumigatus

Question 10

10. Immobilized cell reactors for wastewater treatment have the advantage of having/being

Answer 10

10. All of the above

Question 11

11. Which of the statement is true for continuous reactor at steady state?

Answer 11

11. Biomass, substrate, and product concentrations do not change with time

Question 12

12. A continuous bioreactor in which only the flow rate is used to control the rate of cell or product productivity is called

Answer 12

12. Chemostat

Question 13

13. for organisms growing in a chemostat, the specific growth rate

Answer 13

13. Can be determined from the dilution rate

Question 14

14. Saccharomyces cerevisiae is being grown in a chemostat converts glucose to biomass, ethanol, glycerol, and carbon dioxide. At steady state, the concentration of glucose, biomass, ethanol, and glycerol will

Answer 14

14. Be constant

Question 15

15. In aerobic yeast fermentation for production of citric acid from alkanes using a fed-batch culture, why alkanes are slowly fed to the yeast?

Answer 15

15. Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates

Question 16

16. A continuous reactor has a dilution rate of 0.5/h. Its residence time would be

Answer 16

16. 2 h

Question 17

17. Which of the following is used to calculate mass of substrate in the reactor?

Answer 17

17. Volume of reactor x substrate concentration in reactor

Question 18

18. If biomass yields are constant, then the biomass productivity of a culture growth in continuous reactor will

Answer 18

18. Increase with dilution rate until washout

Question 19

19. Low dissolved oxygen concentrations leads to

Answer 19

19. Low biomass yields

Question 20

20. In a continuous reactor, the medium contains 40 g/L of maltose and the medium flow rate is 10 liters per hour and the effluent contains 20 g/L of lactate. What is the productivity of lactate production from this reactor?

Answer 20

20. 200 g-lactate/L

Question 21

21. A fed-batch reactor containing 1 g/L of substrate in 2 liter of medium. It is fed with 1 g/L of substrate at the rate of 1 liter per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g/L. the mass of substrate that was used by the culture in the reactor was

Answer 21

21. 6g

Question 22

22. Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?

Answer 22

22. ATP is diverted away from anabolism to homeostasis

Question 23

23. The cellular productivity in a continuous stirred tank fermenter (CSTF) increases with an increase in the dilution rate and reaches a maximum value. If the dilution rate is increased beyond the maximum point, the productivity will

Answer 23

23. Decrease abruptly

Question 24

24. Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because

Answer 24

24. All of the above

Question 25

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

Answer 25

25. Initial mass of substrate in the reactor - final mass of substrate in the reactor + flow rate x [substrate in the feed]

Question 26

26. A chemostat has a liquid volume of 2 liters and is being fed at a rate of 4 liters per hour. Dilution rate for this reactor will be

Answer 26

26. 2 h-1

Question 27

27. Mixing per unit volume is observed to be poorest in

Answer 27

27. Continuous packed bed reactor

Question 28

28. The growth of an organism on glucose is described by the following Monod model parameters: μm=0.5 h−1μm​=0.5h−1 and Ks=0.1 g⋅L−1Ks​=0.1g⋅L−1, if the concentration of glucose in the feed is 10 g/L and the dilution rate is set to 0.4/h, then the steady state concentration of glucose in the effluent will be

Answer 28

28. 1.0 g/L

Question 29

29. A continuous reactor at steady state contains 0.04 g/L of biomass and 0.02 g/L of phenol. The feed contained 0.1 g/L of phenol. The biomass yield would be

Answer 29

29. 0.5 g/g

Question 30

30. A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called culture system.

Answer 30

30. Continuous

Question 31

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

Answer 31

31. All of the above

Question 32

32. Fed batch reactors is used to produce vinegar because

Answer 32

32. All of the above

Question 33

33. When a culture of fermenting yeast becomes metabolically uncoupled, ethanol

Answer 33

33. Production becomes non-growth associated

Question 34

34. Mixing profiles closest to plug flow are observed in

Answer 34

34. Continuous packed bed reactor

Question 35

35. On a glucose medium, the growth of an organism is characterized by the following Monod model and stoichiometric parameters

Answer 35

35. 0.5 g/L

Question 36

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

Answer 36

36. Time rate of total amount in reactor = rate of addition to reactor - rate of removal + rate of formation

Question 37

37. A fed-batch reactor initially contains 2 liter of medium. If it was fed at 1 liter per hour, then after 10 hours, the volume of the reactor will be

Answer 37

37. 13 liter

Question 38

38. A Bacillus sp. Produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 liter continuous culture, the steady state productivity of the antibiotic

Answer 38

38. Will be zero

Question 39

39. In a fluidized bed reactor, the function of the disengagement zone is to

Answer 39

39. All of the above

Question 40

40. 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?

Answer 40

40. All of the above