Introduction: Introduction to Fermentation Technology MCQs With Answer is designed for M.Pharm students preparing for bioprocess engineering and industrial pharmacy exams. This set focuses on core concepts of fermentation technology: microbial metabolism, reactor types (batch, fed-batch, continuous), upstream operations (inoculum development, media, sterilization), mass transfer and oxygen transfer fundamentals (kLa, OUR), process control (pH, temperature, antifoam), scale-up challenges and basics of downstream processing. Each question highlights practical and theoretical aspects you will encounter in pharmaceutical fermentation development and manufacturing. Practicing these MCQs will strengthen conceptual understanding and application skills needed for coursework, research projects, and industry roles.
Q1. What best defines fermentation technology in a pharmaceutical context?
- Use of chemical catalysts to convert substrates into products
- Process using microorganisms to produce desired products under controlled conditions
- Sterile distillation of plant extracts for drug production
- Mechanical separation of biomolecules without biological agents
Correct Answer: Process using microorganisms to produce desired products under controlled conditions
Q2. Which statement correctly distinguishes primary from secondary metabolites?
- Primary metabolites are produced mainly during stationary phase; secondary during exponential phase
- Primary metabolites are produced during exponential growth and are essential for cell growth
- Secondary metabolites are simple sugars and organic acids used for growth
- Primary metabolites are always toxic and used for biocontrol
Correct Answer: Primary metabolites are produced during exponential growth and are essential for cell growth
Q3. Which fermentation mode is characterized by no addition or removal of medium once the run has started?
- Continuous culture
- Fed-batch culture
- Batch culture
- Perfusion culture
Correct Answer: Batch culture
Q4. In an aerobic stirred-tank bioreactor, which component primarily introduces gas into the liquid phase?
- Impeller
- Sparger
- Baffle
- Foam breaker
Correct Answer: Sparger
Q5. What does the term kLa represent in bioprocess engineering?
- Equilibrium oxygen solubility in medium
- Volumetric oxygen mass transfer coefficient
- Specific growth rate constant
- Rate constant for substrate consumption
Correct Answer: Volumetric oxygen mass transfer coefficient
Q6. The Monod equation describes the relationship between which two variables?
- Biomass concentration and dissolved oxygen
- Specific growth rate and limiting substrate concentration
- pH and temperature optima for growth
- Product formation rate and agitation speed
Correct Answer: Specific growth rate and limiting substrate concentration
Q7. Which sterilization method is preferred for heat-labile media components and air gas streams?
- Autoclaving at 121°C
- Dry heat sterilization
- Membrane filtration
- Gamma irradiation
Correct Answer: Membrane filtration
Q8. What is the main objective of inoculum development in pharmaceutical fermentation?
- To produce finished product directly in the seed flask
- To generate a high-viability, physiologically active culture at the required volume and phase for inoculation
- To sterilize media components before scale-up
- To test downstream purification steps
Correct Answer: To generate a high-viability, physiologically active culture at the required volume and phase for inoculation
Q9. Which is the most common immediate control strategy for excessive foaming during fermentation?
- Increase aeration rate substantially
- Add antifoam agents or use mechanical foam breakers
- Decrease inoculum size
- Raise cultivation temperature above optimum
Correct Answer: Add antifoam agents or use mechanical foam breakers
Q10. Which biological indicator is commonly used to validate steam sterilization (autoclave) performance?
- Escherichia coli vegetative cells
- Geobacillus stearothermophilus spores
- Saccharomyces cerevisiae yeast cells
- Pseudomonas aeruginosa biofilm
Correct Answer: Geobacillus stearothermophilus spores
Q11. Oxygen uptake rate (OUR) refers to which process parameter?
- Rate at which oxygen dissolves into medium in the absence of cells
- Rate at which cells consume dissolved oxygen per unit time
- Maximum oxygen concentration achievable in the reactor
- Rate of oxygen generation by phototrophic organisms
Correct Answer: Rate at which cells consume dissolved oxygen per unit time
Q12. The biomass yield coefficient Yx/s quantifies what relationship?
- Volume of gas produced per gram biomass
- Biomass formed per unit substrate consumed
- Substrate concentration per unit time
- Product formed per unit biomass
Correct Answer: Biomass formed per unit substrate consumed
Q13. What is a principal advantage of immobilized cell systems in fermentation?
- They always eliminate the need for downstream processing
- Allow higher cell densities and repeated or continuous use of biocatalyst
- Prevent any mass transfer limitations
- Ensure sterile conditions without filtration
Correct Answer: Allow higher cell densities and repeated or continuous use of biocatalyst
Q14. During scale-up of an aerobic fermentation, which factor most commonly limits performance in larger reactors?
- Inability to maintain sterile air supply
- Oxygen transfer and mixing limitations (kLa and gradients)
- Excessive nutrient concentration at large scale
- Decreased viscosity of culture broth
Correct Answer: Oxygen transfer and mixing limitations (kLa and gradients)
Q15. How is pH typically controlled online during a pharmaceutical fermentation run?
- By periodic manual sampling and offline titration only
- Using a pH probe with automated addition of acid or base
- By altering the inoculum size mid-run
- By changing ambient room humidity
Correct Answer: Using a pH probe with automated addition of acid or base
Q16. Which practice ensures aseptic sampling from a production bioreactor?
- Opening the reactor headspace briefly to insert a syringe
- Using sterile sampling valves or ports with sterile syringes and trained technique
- Removing a handful of culture with bare hands and placing into sterile tube
- Sampling through an unclean glass flask
Correct Answer: Using sterile sampling valves or ports with sterile syringes and trained technique
Q17. What is generally the first unit operation in downstream processing after fermentation broth is harvested?
- Chromatographic polishing
- Cell separation (centrifugation or microfiltration)
- Lyophilization
- Spray drying
Correct Answer: Cell separation (centrifugation or microfiltration)
Q18. Secondary metabolite production in microorganisms is often triggered by which condition?
- Excess of easily metabolized nutrients and rapid exponential growth
- Nutrient limitation or stress leading to stationary phase physiology
- High dissolved oxygen and low cell density
- Continuous removal of biomass from the reactor
Correct Answer: Nutrient limitation or stress leading to stationary phase physiology
Q19. Increasing agitation speed in a stirred bioreactor typically leads to which direct effect?
- Decrease in shear forces experienced by cells
- Increase in volumetric oxygen transfer coefficient (kLa) and mixing rate
- Reduction in heat transfer from the vessel
- Complete elimination of oxygen gradients regardless of scale
Correct Answer: Increase in volumetric oxygen transfer coefficient (kLa) and mixing rate
Q20. In a continuous stirred tank reactor (CSTR) run at steady state, which relationship holds true?
- Specific growth rate is zero while dilution rate is high
- Specific growth rate equals the dilution rate at steady state
- Substrate concentration always equals feed concentration
- Biomass concentration increases indefinitely with time
Correct Answer: Specific growth rate equals the dilution rate at steady state
