1. Which scientist(s) pointed out that the stationary phase is a misnomer in terms of the physiology of organism?
a) Burrow et al.
b) Bu’Lock et al.
c) Bull
d) Monod
Explanation: Bull in 1974 pointed out that the stationary phase is a misnomer in terms of the physiology of organism as the population is still metabolically active during this phase.
2. What is Idiophase?
a) Production of secondary metabolites
b) Production of primary metabolites
c) Production of tertiary metabolites
d) Production of quaternary metabolites
Explanation: Idiophase refers to the period subsequent to the exponential phase where secondary metabolites are synthesized.
3. Borrow et al. investigated the biosynthesis of Gibberellic acid by Gibberella fujikuroi and divided growth of organisms into balanced, storage and maintenance phase. What do you mean by storage phase?
a) The phase equivalent to the early to middle exponential phase
b) The phase equivalent to the late exponential phase
c) The phase equivalent to the stationary phase
d) The phase equivalent to the lag phase
Explanation: Storage phase means the phase equivalent to the late exponential phase where the increase in mass is due to the accumulation of lipid and carbohydrate.
4. The batch culture or fermentation can be used to produce ________
a) Organic acids
b) Amino acids
c) Single Cell Protein
d) Antibiotics
Explanation: The batch culture or fermentation can be used to produce primary metabolites such as antibiotics which help in retarding the growth of bacteria. Organic acids, amino acids, SCP can be prepared by Continuous fermentation.
5. The Continuous culture is a/an ______ culture system.
a) Open
b) Closed
c) Isolated
d) Semi-closed
Explanation: The Continuous culture is an open culture system where the nutrients are added in a continuous fashion. The batch culture is a closed system with limiting the number of nutrients and fed-batch culture is a semi-closed system
6. During continuous culture/fermentation, nutrients in the fermenter are utilized at a fast rate.
a) true
b) false
Explanation: In Continuous Fermentation, the nutrients in the fermenter are added continuously and are utilized by microbes at a fast rate whereas, in batch culture, the nutrients are utilized at a slow rate.
7. Which Growth phase is usually longer in continuous culture?
a) Log
b) Exponential
c) Stationary
d) Death
Explanation: Exponential phase is usually longer as the nutrients are added continuously and therefore the microbes show exponential growth. This is the phase of the maximum growth rate where the growth of cells usually increases.
8. What is the dilution rate (D)?
a) D = F/V
b) D = V/F
c) D = µF
d) D = µD
Explanation: The flow of medium into the vessel is called dilution rate, and is defined as,
D = F/V
where V is volume and F is the flow rate.
9. What is the unit of flow rate (F)?
a) dm3 h-1
b) km3 h-1
c) ml3 h-2
d) dm2 h-2
Explanation: Flow rate is the product of dilution rate and volume of the vessel. The unit of dilution rate is h-1 and that of the volume of the vessel is dm3. Therefore, the unit of flow rate is dm3 h-1.
10. The chemostat and turbidostat are the types of bioreactors that are used in which of the following culture?
a) Batch culture
b) Continuous culture
c) Fed-Batch culture
d) Solid State culture
Explanation: Turbidostat is a microbiological culture device, similar to a chemostat, which has feedback between the turbidity of the culture vessel and the dilution rate. Continuous fermentation is useful in the production of potentially more important products than batch fermentation.