250+ TOP MCQs on Microbial Fermentation – 1 and Answers

Chemical Reaction Engineering Multiple Choice Questions & Answers on “ Microbial Fermentation – 1”.

1. State true or false.
Kinetics of microbial fermentation cannot be expressed by Monod kinetics.
A. True
B. False
View Answer

Answer: B

3. The hierarchy of phases for the microbes in a fermentation process is ____
A. Exponential growth phase → Lag phase → Stationary phase → Death phase
B. Stationary phase → Lag phase → Exponential growth phase → Death phase
C. Lag phase → Exponential growth phase → Stationary phase → Death phase
D. Lag phase → Stationary phase → Exponential growth phase → Death phase
View Answer

Answer: C
Explanation: There is an initial lag phase for the microbial cells to begin growth and reproduction. The cells then grow exponentially and there exists a stationary growth less phase. Eventual death of cells is observed due to depletion of food.

4. The substrate limiting kinetics of A (^{underrightarrow{C}}) C + R is the one in which ___
A. Final concentration of C depends on initial amount of food
B. Final concentration of C does not depend on initial amount of food
C. Final concentration of C does not exceed a certain value
D. The rate depends on enzyme concentration
View Answer

Answer: A
Explanation: The amount of food determines the progress of the reaction. Product does not affect the reaction rate.

5. The poison limiting kinetics of A (^{underrightarrow{C}}) C + R is the one in which ___
A. Final concentration of C depends on initial amount of food
B. Final concentration of C does not depend on initial amount of food
C. Final concentration of C does not exceed a certain value
D. The rate depends on enzyme concentration
View Answer

Answer: C
Explanation: The product slows down the reaction. After sometime, the product concentration increases and the reaction cease to occur.

7. In a batch fermenter, for substrate limiting kinetics, C_C,max is ________
A. Independent of C_A0
B. Directly proportional to C_A0
C. Inversely proportional to C_A0
D. Proportional to the square of C_A0
View Answer

Answer: B
Explanation: At low C_A0, C_C,max α C_A0. For high C_A0, C_C,max is independent of C_A0.

8. With an accumulation of waste formed during the reaction, the value of observed Monod rate constant ____
A. Decreases
B. Increases
C. Remains constant
D. First decreases and then increases
View Answer

Answer: A
Explanation: The accumulation of waste formed decelerates the reaction rate. This decrease is reflected in the reaction rate constant.

9. The relationship between the Monod rate constant, k and the rate constant observed due to waste accumulation k_obs is ____
A. k_obs = k (1-(frac{C_R}{C_R^*}))ⁿ
B. k_obs = k (1-(frac{C_R}{C_R^*})^frac{1}{n})
C. k = k_obs (1-(frac{C_R}{C_R^*}))ⁿ
D. k_obs = k ((frac{C_R}{C_R^*}))ⁿ
C_R* is the concentration of R where cell activity stops and n is the order of product poisoning.
View Answer

Answer: A
Explanation: k_obs = k (1-(frac{C_R}{C_R^*}))ⁿ
The buildup of harmful wastes interferes with the cell multiplication. The observed rate constant decreases with a rise in C_R.

10. The fractional yield of C with respect to A for the reaction A (^{underrightarrow{C}}) cC + rR is the ratio of ____
A. All R formed to all A reacted
B. All A reacted to all R formed
C. All A reacted to all C formed
D. All C formed to all A reacted
View Answer

Answer: D
Explanation: Fractional yield is the ratio of product formed to the total reactant fed. It is the ratio of all C formed to all A reacted.