250+ TOP MCQs on Ideal Reactor Operation and Answers

Bioprocess Engineering Multiple Choice Questions on “Ideal Reactor Operation”.

1. Aerobic reactions are not batch operations.
A. True
B. False

Answer: A
Explanation: Aerobic reactions are not batch operations in the strictest sense; the low solubility of oxygen in aqueous media means that it must be supplied continuously while carbon dioxide and other off-gases are removed.

2. In a perfectly mixed reactor _________
A. The output composition is different from input composition
B. The output composition is identical from input composition
C. Both output and input composition are constant
D. Both output and input composition are not constant

Answer: B
Explanation: In a perfectly mixed reactor, the output composition is identical to composition of the material inside the reactor, which is a function of residence time and rate of reaction.

3. Convert v_max = 2.5 mmol m^-3 s^-1 into mM h^-1.
A. 2500
B. 900
C. 25
D. 9

4. Convert v_max = 7 mmol m^-3 s^-1 into mM h^-1.
A. 25
B. 20
C. 25.20
D. 20.25

5. In batch reaction time with enzyme deactivation, calculate the first-order deactivation rate constant.
(Given – s_o = 12 mM; v_max = 9 mM h^-1; K_m = 8.9 mM; s_f = 1.2 mM; t_h = 4.4 h).
A. 0.150 h^-1
B. 0.158 h^-1
C. 0.155 h^-1
D. 0.154 h^-1

6. By taking the parameters of Q5, and the batch reaction time t_b.
A. 5.0 h
B. 10.0 h
C. 15.0 h
D. 20.0 h

7. Zymomonas mobilis is used to convert glucose to ethanol in a batch fermenter under anaerobic conditions. The yield of biomass from substrate is 0.06 g g^-1; Y_PX is 7.7 g g^-1. The maintenance coefficient is 2.2 g g^-1 h^-1; the specific rate of product formation due to maintenance is 1.1 h^-1. The maximum specific growth rate of Z. mobilis is approximately 0.3 h^-1.5 g bacteria are inoculated into 50 litres of medium containing 12 g l^-1 glucose. Determine batch culture times required to produce 10 g biomass.
A. 3.1 h
B. 3.3 h
C. 3.5 h
D. 3.7 h

8. By taking the pararmeters of Q7 and Determine batch culture times required to achieve 90% substrate conversion.
A. 5.1 h
B. 5.3 h
C. 5.5 h
D. 5.7 h

9. By taking the parameters question 8 and question 7, determine batch culture times required to produce 100 g ethanol.
A. 3.2 h
B. 3.4 h
C. 3.6 h
D. 3.8 h

10. The Zymomonas mobilis cells are used for chemostat culture in a 60 m³ fermenter. The feed contains 12 g l^-1 glucose; K_s for the organism is 0.2 g l^-1. What flow rate is required for a steady-state substrate concentration of 1.5 g l^-1?
A. 15.6 m³ h^-1
B. 15.8 m³ h^-1
C. 15.4 m³ h^-1
D. 15.2 m³ h^-1

12. By taking Q10 and Q11 into account and at the flow rate of Q10, what concentration of ethanol is produced?
A. 5.1 g l^-1
B. 5.3 g l^-1
C. 5.5 g l^-1
D. 5.7 g l^-1

13. Which of the following type is of the perfusion culture?
A. Batch
B. Conc. Batch
C. Continuous
D. Conc. Fed-Batch

Answer: D
Explanation: Concentrated Fed-Batch- In a process that can be considered a form of perfusion, the culture is perfused to generate ultrahigh cell concentration, greater than 10⁸ cells/mL; and the product is also retained in the vessel.

14. Immobilised lactase is used to hydrolyse lactose in dairy waste to glucose and galactose. Enzyme is immobilised in resin particles and packed into a 0.5 m³ column. The total effectiveness factor for the system is close to unity; K_m for the immobilised enzyme is 1.32 kg m^-3; V_max is 45 kg m^-3 h^-1. The lactose concentration in the feed stream is 9.5 kg m^-3; a substrate conversion of 98% is required. The column is operated with plug flow for a total of 310 d per year. At what flow rate should the reactor be operated?
A. 1.56 m³ h^-1
B. 1.58 m³ h^-1
C. 1.50 m³ h^-1
D. 1.54 m³ h^-1

15. By taking the parameters of Q14 into consideration, estimate how many tonnes of glucose are produced per year?
A. 56.3 tonnes yr^-1
B. 56.6 tonnes yr^-1
C. 56.7 tonnes yr^-1
D. 56.5 tonnes yr^-1