Fermentation Kinetics problems
- 1. Lag phase occurs mainly due to
Options- A. acclimatization with new environment and substrate
- B. higher growth temperature
- C. substrate disliking
- D. variation in substrate concentration Discuss
Correct Answer: acclimatization with new environment and substrate
- 2. The relatively large volume (10 to 40% of total fermenter volume) of the seed culture is employed to
Options- A. increase the overall fermentation time
- B. increase the overall yield of biomass
- C. decrease the overall fermentation time
- D. decrease the overall yield of product Discuss
Correct Answer: decrease the overall fermentation time
- 3. In an airlift bioreactor, the air sparging region is called
Options- A. downcomer
- B. disengagement zone
- C. air riser
- D. none of these Discuss
Correct Answer: air riser
- 4. Residence time distribution (RTD) of a reactor is independent of
Options- A. micro mixing
- B. volume of reactor
- C. height of the reactor
- D. width of the reactor Discuss
Correct Answer: micro mixing
- 5. Concentration of the growth limiting substrate means
Options- A. trace elements concentration
- B. the concentration of the substrate that controls the growth rate of the cells
- C. sugar concentration in the fermentation medium
- D. dissolved oxygen concentration Discuss
Correct Answer: the concentration of the substrate that controls the growth rate of the cells
- 6. At the end of the lag phase, when growth begins, the division rate increases gradually and reaches a maximum value in the exponential growth period. This transitional period is commonly called the accelerated growth phase and is often included as a part of the
Options- A. lag phase
- B. stationary phase
- C. death phase
- D. exponential growth phase Discuss
Correct Answer: lag phase
- 7. Which of the following(s) is/are considered the limitations of the exponential growth model?
Options- A. Only predicts that cells grow exponentially during the log phase
- B. It does not consider factors that causes cells growth to stop or slow
- C. Predicts cell growth at a linear rate
- D. All of the above Discuss
Correct Answer: It does not consider factors that causes cells growth to stop or slow
- 8. The optical density sometimes drops during the lag phase because
Options- A. cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
- B. of fast cell growth causing them to fill up with DNA
- C. cells swell up with water
- D. cells swell up with RNA Discuss
Correct Answer: cells tend to grow without dividing leading to a decrease in the surface area to volume ratio
- 9. Stirred tank fermenter (STF) can be employed for
Options- A. aerobic fermentation of a wide range of cells including microbial, animal and plant cells
- B. anaerobic fermentation of a wide range of cells including microbial, animal and plant cells
- C. Both (a) and (b)
- D. anaerobic fermentation of plant cells only Discuss
Correct Answer: Both (a) and (b)
- 10. Which of the following statements would be appropriate while comparing bubble column and air lift fermenter of the same size?
Options- A. The average bubble size is smaller in an airlift bioreactor
- B. Oxygen transfer rate is higher in an airlift bioreactor
- C. The surface area for gas exchange is higher in an airlift bioreactor
- D. All of the above Discuss
Correct Answer: All of the above
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