Q.1 Which bioreactor type uses a rotating vessel to create a low-shear, low-oxygen environment for mammalian cells?
Stirred-tank bioreactor
Airlift bioreactor
Rotating Wall Vessel (RWV)
Packed-bed bioreactor
Explanation - The Rotating Wall Vessel (RWV) is designed to provide a microgravity-like, low-shear environment that is ideal for the cultivation of sensitive mammalian cells.
Correct answer is: Rotating Wall Vessel (RWV)
Q.2 In which bioreactor type is the liquid phase continuously stirred by a mechanical impeller?
Stirred-tank bioreactor
Wave bioreactor
Membrane bioreactor
Fluidized-bed bioreactor
Explanation - Stirred-tank bioreactors use a mechanical impeller to maintain homogenous mixing of the culture medium.
Correct answer is: Stirred-tank bioreactor
Q.3 Which bioreactor type employs a gas-phase circulation to create buoyancy-driven flow?
Stirred-tank
Airlift
Packed-bed
Continuous stirred tank
Explanation - An airlift bioreactor relies on the buoyancy of bubbles to induce circulation without mechanical stirrers.
Correct answer is: Airlift
Q.4 What is the primary advantage of a packed-bed bioreactor for enzyme immobilization?
High oxygen transfer rate
High shear environment
Easy product recovery
High surface area for attachment
Explanation - Packed-bed bioreactors provide a large surface area where immobilized enzymes can adhere, enhancing catalytic activity.
Correct answer is: High surface area for attachment
Q.5 Which bioreactor type uses a membrane for selective separation of cells from the culture medium?
Packed-bed
Microcarrier
Membrane bioreactor
Fluidized-bed
Explanation - Membrane bioreactors incorporate semi-permeable membranes to separate cells or products from the broth.
Correct answer is: Membrane bioreactor
Q.6 In a wave bioreactor, what motion primarily promotes mixing?
Rotational stirring
Continuous rocking
Impeller agitation
Gas sparging
Explanation - Wave bioreactors rely on a gentle rocking motion to create surface waves that mix the culture without mechanical agitation.
Correct answer is: Continuous rocking
Q.7 Which bioreactor type is best suited for high-density, suspended cell cultures with low shear sensitivity?
Stirred-tank
Microcarrier
Wave
Airlift
Explanation - Wave bioreactors offer low shear and good oxygen transfer, making them ideal for sensitive cells.
Correct answer is: Wave
Q.8 Which bioreactor type uses a fluidized bed of beads to provide cell attachment sites?
Packed-bed
Fluidized-bed
Microcarrier
Airlift
Explanation - Fluidized-bed bioreactors have a bed of beads that become fluidized by the flow, allowing cells to attach to the beads.
Correct answer is: Fluidized-bed
Q.9 In a continuous stirred-tank bioreactor, which parameter is critical for maintaining steady-state operation?
Inoculum size
Feed rate
Initial pH
Batch volume
Explanation - The feed rate determines the input of fresh nutrients and controls the dilution rate in continuous operation.
Correct answer is: Feed rate
Q.10 What distinguishes a fed-batch bioreactor from a batch bioreactor?
Continuous removal of product
Addition of substrates during cultivation
Use of gas sparging
Use of a mechanical stirrer
Explanation - Fed-batch systems add nutrients gradually to prolong growth phases, unlike batch systems that start with a fixed volume.
Correct answer is: Addition of substrates during cultivation
Q.11 Which bioreactor type is typically used for large-scale fermentation of yeast?
Stirred-tank
Packed-bed
Microcarrier
Membrane
Explanation - Stirred-tank bioreactors provide excellent mixing and oxygen transfer, essential for yeast fermentation at scale.
Correct answer is: Stirred-tank
Q.12 Which type of bioreactor uses a moving air column to create circulation without mechanical stirrers?
Stirred-tank
Airlift
Wave
Microcarrier
Explanation - Airlift bioreactors rely on buoyancy-driven flow of liquid and air within a tube to provide mixing.
Correct answer is: Airlift
Q.13 What is a primary limitation of packed-bed bioreactors for microbial cultures?
Low oxygen transfer
High shear stress
Difficulty in scale-up
Limited product recovery
Explanation - The dense packing reduces gas-liquid mass transfer, limiting oxygen availability for aerobic microbes.
Correct answer is: Low oxygen transfer
Q.14 Which bioreactor type employs a rotating disc to create a low-shear environment for 3D cell cultures?
Stirred-tank
Airlift
Rotating disc
Microcarrier
Explanation - Rotating disc (or rotary cell culture) systems use a disc that spins to mimic microgravity and reduce shear.
Correct answer is: Rotating disc
Q.15 In which bioreactor type is a gas sparger used to increase oxygen transfer by creating small bubbles?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Stirred-tank bioreactors incorporate gas spargers to introduce oxygen in a mixed environment.
Correct answer is: Stirred-tank
Q.16 Which bioreactor type is best suited for the cultivation of photosynthetic microorganisms?
Stirred-tank
Wave
Airlift
Microcarrier
Explanation - Wave bioreactors provide good light penetration and gentle mixing, ideal for photosynthetic cultures.
Correct answer is: Wave
Q.17 What is the main advantage of a microcarrier-based bioreactor for cell culture?
High oxygen transfer rate
Large surface area for cell attachment
Low shear stress
Easy sterilization
Explanation - Microcarriers provide a high surface area-to-volume ratio, allowing cells to grow in suspension while attached.
Correct answer is: Large surface area for cell attachment
Q.18 Which bioreactor type is characterized by a vertical tube with a gas and liquid inlet at the bottom and outlet at the top?
Stirred-tank
Airlift
Packed-bed
Fluidized-bed
Explanation - The airlift design features a vertical tube with gas and liquid inlets, creating upward flow and circulation.
Correct answer is: Airlift
Q.19 In a membrane bioreactor, what is the typical purpose of the membrane?
To provide a surface for cell attachment
To separate cells from the medium
To increase mixing speed
To increase temperature control
Explanation - The semi-permeable membrane in MBRs selectively retains cells while allowing permeate to pass.
Correct answer is: To separate cells from the medium
Q.20 Which bioreactor type can operate with a continuous inlet of fresh medium and removal of excess fluid while maintaining a fixed volume?
Batch
Fed-batch
Continuous stirred-tank
Airlift
Explanation - Continuous stirred-tank bioreactors (CSTRs) sustain a steady state by balancing inflow and outflow volumes.
Correct answer is: Continuous stirred-tank
Q.21 What is the main design feature of a fluidized-bed bioreactor?
Fixed bed of solid supports
Liquid circulation via sparging
Fluidization of solid support by liquid flow
Rotating disc for microgravity
Explanation - Fluidized-bed bioreactors use a high liquid velocity to make solid supports behave as a fluid, enhancing mass transfer.
Correct answer is: Fluidization of solid support by liquid flow
Q.22 Which bioreactor type is commonly used for the production of monoclonal antibodies in mammalian cell culture?
Stirred-tank
Wave
Microcarrier
Airlift
Explanation - Microcarrier-based stirred-tank systems allow high cell densities while providing attachment sites for mammalian cells.
Correct answer is: Microcarrier
Q.23 What distinguishes a wave bioreactor from a stirred-tank bioreactor?
Presence of an impeller
Use of a rocking motion
Higher shear stress
Higher oxygen transfer rate
Explanation - Wave bioreactors rely on rocking motion instead of mechanical impellers for mixing.
Correct answer is: Use of a rocking motion
Q.24 Which bioreactor type is most suitable for scaling up by increasing impeller diameter proportionally to vessel size?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank design allows scale-up through geometrically similar scaling laws involving impeller diameter.
Correct answer is: Stirred-tank
Q.25 In a packed-bed bioreactor, what is the main cause of high pressure drop across the bed?
High liquid velocity
Large particle size
Low bed height
High gas flow rate
Explanation - Increasing liquid velocity through a packed bed raises the pressure drop due to resistance to flow.
Correct answer is: High liquid velocity
Q.26 Which bioreactor type uses a rotating cylinder with a small air inlet to create a wave-like motion?
Wave
Stirred-tank
Airlift
Rotating disc
Explanation - Wave bioreactors have a cylindrical vessel that rocks, generating waves for mixing.
Correct answer is: Wave
Q.27 Which bioreactor type typically has the highest gas-liquid mass transfer coefficient (kLa)?
Airlift
Stirred-tank
Wave
Membrane
Explanation - Stirred-tank bioreactors can achieve high kLa due to efficient gas sparging and mechanical mixing.
Correct answer is: Stirred-tank
Q.28 Which bioreactor type is most suitable for culturing adherent plant cells?
Microcarrier
Airlift
Packed-bed
Wave
Explanation - Microcarriers provide a substrate for plant cells to attach and grow in suspension cultures.
Correct answer is: Microcarrier
Q.29 What is the main challenge when scaling up a microcarrier bioreactor?
Maintaining adequate mixing
Controlling temperature
Preventing microcarrier aggregation
Providing sufficient light
Explanation - As scale increases, ensuring uniform suspension and preventing clumping of microcarriers becomes difficult.
Correct answer is: Preventing microcarrier aggregation
Q.30 Which bioreactor type uses a bubble column to provide mixing and oxygen transfer?
Stirred-tank
Bubble column
Airlift
Packed-bed
Explanation - Bubble column reactors rely on rising gas bubbles for mixing and oxygen supply without mechanical agitation.
Correct answer is: Bubble column
Q.31 In a wave bioreactor, what is the typical depth of the liquid during rocking?
10 mm
20 mm
30 mm
40 mm
Explanation - Wave bioreactors generally maintain a liquid depth of about 30 mm to promote efficient mixing while preventing splashing.
Correct answer is: 30 mm
Q.32 Which bioreactor type is commonly used for the production of recombinant proteins in E. coli?
Stirred-tank
Airlift
Microcarrier
Packed-bed
Explanation - Stirred-tank bioreactors offer excellent control over temperature and oxygen, which are critical for E. coli cultures.
Correct answer is: Stirred-tank
Q.33 What is the purpose of using a gas-permeable membrane in a membrane bioreactor?
To retain cells
To increase mixing speed
To allow gas transfer
To provide a support surface
Explanation - Gas-permeable membranes enable oxygen to diffuse directly into the culture while retaining cells.
Correct answer is: To allow gas transfer
Q.34 Which bioreactor type can be operated in a continuous mode with a constant dilution rate?
Batch
Fed-batch
CSTR
Airlift
Explanation - Continuous stirred-tank reactors (CSTRs) maintain a constant dilution rate by balancing inflow and outflow.
Correct answer is: CSTR
Q.35 What is a key design parameter for a packed-bed bioreactor?
Impeller speed
Bed porosity
Sparger design
Wave frequency
Explanation - Bed porosity affects flow distribution and oxygen transfer efficiency in packed-bed systems.
Correct answer is: Bed porosity
Q.36 Which bioreactor type is often used for the production of biopharmaceuticals at industrial scale?
Wave
Microcarrier
Stirred-tank
Airlift
Explanation - Stirred-tank bioreactors provide the necessary control and scalability for large-scale biopharma production.
Correct answer is: Stirred-tank
Q.37 In a fluidized-bed bioreactor, what happens to the solid support when the liquid velocity exceeds a critical value?
They settle at the bottom
They become fluidized
They clump together
They dissolve
Explanation - Exceeding the critical liquid velocity turns the solid support into a fluidized state, enhancing mass transfer.
Correct answer is: They become fluidized
Q.38 Which bioreactor type is best for low-shear, microgravity-like environments?
Airlift
Rotating Wall Vessel
Packed-bed
Stirred-tank
Explanation - The RWV provides a low-shear environment mimicking microgravity, ideal for sensitive cells.
Correct answer is: Rotating Wall Vessel
Q.39 Which type of bioreactor is characterized by a single tank with a continuous feed and effluent, but without a mechanical stirrer?
Stirred-tank
Airlift
Packed-bed
Bubble column
Explanation - Bubble column bioreactors rely on gas bubbles for mixing and do not use mechanical agitation.
Correct answer is: Bubble column
Q.40 What is the main advantage of a wave bioreactor for cell culture?
High shear stress
Low shear stress
High oxygen transfer rate
Ease of sterilization
Explanation - Wave bioreactors offer gentle mixing, reducing shear damage to delicate cells.
Correct answer is: Low shear stress
Q.41 Which bioreactor type is commonly used for the cultivation of fungi in submerged fermentation?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank bioreactors provide efficient mixing and oxygen transfer essential for fungal growth.
Correct answer is: Stirred-tank
Q.42 In a membrane bioreactor, what is the typical pore size range for cell retention?
0.1–0.5 µm
0.5–2 µm
2–5 µm
5–10 µm
Explanation - Membrane pore sizes of 0.5–2 µm are common for retaining mammalian cells while allowing permeate.
Correct answer is: 0.5–2 µm
Q.43 Which bioreactor type can be scaled up by increasing the number of impellers proportionally to the vessel size?
Stirred-tank
Airlift
Microcarrier
Wave
Explanation - Stirred-tank designs can be scaled by adding more impellers while maintaining geometric similarity.
Correct answer is: Stirred-tank
Q.44 What is the main drawback of using a packed-bed bioreactor for mammalian cell culture?
High oxygen transfer
Difficulty in cell harvesting
High shear stress
Large footprint
Explanation - Packed beds trap cells, making recovery for downstream processing more challenging.
Correct answer is: Difficulty in cell harvesting
Q.45 Which bioreactor type uses a vertical tube with an inner and outer column to separate gas and liquid flows?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - The airlift design features an inner gas column and outer liquid column to create circulation.
Correct answer is: Airlift
Q.46 Which type of bioreactor is most commonly used for the production of insulin using bacterial fermentation?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Stirred-tank reactors provide precise control over temperature and aeration, essential for insulin production.
Correct answer is: Stirred-tank
Q.47 What is a key design consideration for a microcarrier bioreactor?
Surface area of the vessel
Surface area of the microcarrier
Number of impellers
Volume of the gas sparger
Explanation - The surface area of microcarriers directly influences cell attachment and growth capacity.
Correct answer is: Surface area of the microcarrier
Q.48 Which bioreactor type is specifically designed for cell therapy production requiring high cell densities?
Stirred-tank
Wave
Microcarrier
Airlift
Explanation - Microcarrier systems enable high cell densities while allowing gentle culture conditions for cell therapy.
Correct answer is: Microcarrier
Q.49 In a wave bioreactor, which parameter primarily controls the mixing intensity?
Rocking frequency
Impeller speed
Gas flow rate
Temperature
Explanation - The rocking frequency determines how fast the waves propagate, thus controlling mixing strength.
Correct answer is: Rocking frequency
Q.50 Which type of bioreactor can be used for the cultivation of algae in photobioreactors?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Airlift reactors provide efficient gas exchange and gentle mixing, suitable for algae growth.
Correct answer is: Airlift
Q.51 What is a significant advantage of a bubble column bioreactor?
High shear stress
Low oxygen transfer
Simple design with no moving parts
High cost
Explanation - Bubble column reactors have a straightforward design, reducing maintenance and operating costs.
Correct answer is: Simple design with no moving parts
Q.52 Which bioreactor type relies on a gas-permeable membrane for oxygen transfer while maintaining a sterile environment?
Stirred-tank
Membrane bioreactor
Packed-bed
Microcarrier
Explanation - Membrane bioreactors use oxygen-permeable membranes to supply oxygen directly into the culture.
Correct answer is: Membrane bioreactor
Q.53 Which of the following is NOT a typical feature of a stirred-tank bioreactor?
Mechanical impeller
Gas sparger
Wave motion
Temperature control
Explanation - Stirred-tank reactors use impellers for mixing; wave motion is characteristic of wave bioreactors.
Correct answer is: Wave motion
Q.54 Which type of bioreactor is best suited for large-scale production of recombinant viruses?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank reactors provide high oxygen transfer and uniform mixing, critical for virus replication.
Correct answer is: Stirred-tank
Q.55 In a fluidized-bed bioreactor, what is the typical range of liquid velocity used to maintain fluidization?
0.01–0.05 m/s
0.05–0.2 m/s
0.2–1.0 m/s
1.0–5.0 m/s
Explanation - Fluidization typically occurs within the 0.05–0.2 m/s range, balancing fluid support with particle stability.
Correct answer is: 0.05–0.2 m/s
Q.56 Which bioreactor type is commonly used in pilot-scale studies for microbial fermentation?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Stirred-tank reactors are versatile and scalable, making them standard in pilot-scale fermentations.
Correct answer is: Stirred-tank
Q.57 What is the primary purpose of adding a gas-permeable membrane in a membrane bioreactor?
To provide a support surface
To allow gas exchange without mixing
To increase impeller speed
To reduce temperature
Explanation - The membrane permits gas diffusion while maintaining a clear separation from the liquid phase.
Correct answer is: To allow gas exchange without mixing
Q.58 Which type of bioreactor provides a high surface-to-volume ratio for cell attachment?
Packed-bed
Microcarrier
Wave
Stirred-tank
Explanation - Microcarriers significantly increase the available surface area for adherent cell growth.
Correct answer is: Microcarrier
Q.59 In a wave bioreactor, what typically limits the maximum cell density that can be achieved?
Shear stress
Oxygen transfer
Nutrient limitation
Temperature control
Explanation - The low kLa in wave bioreactors can limit cell proliferation at high densities.
Correct answer is: Oxygen transfer
Q.60 Which bioreactor type uses a rotating cylinder to create a low-shear, microgravity environment for cell culture?
Rotating Wall Vessel
Stirred-tank
Airlift
Packed-bed
Explanation - The RWV provides a low-shear, microgravity-like environment using a rotating cylinder.
Correct answer is: Rotating Wall Vessel
Q.61 Which of the following is a typical disadvantage of a bubble column reactor?
High shear stress
Poor oxygen transfer
Large capital cost
Complex mechanical parts
Explanation - Bubble columns may suffer from lower kLa compared to stirred-tank reactors.
Correct answer is: Poor oxygen transfer
Q.62 In a packed-bed bioreactor, what is the main factor that limits the maximum achievable biomass?
Heat transfer
Shear stress
Oxygen transfer
Light penetration
Explanation - Limited oxygen transfer in packed beds restricts aerobic biomass accumulation.
Correct answer is: Oxygen transfer
Q.63 Which bioreactor type typically requires the least mechanical maintenance?
Stirred-tank
Airlift
Wave
Packed-bed
Explanation - Airlift reactors have no impellers, reducing mechanical wear and maintenance.
Correct answer is: Airlift
Q.64 What is the main advantage of using a fluidized-bed bioreactor for biofuel production?
High oxygen transfer
Low shear stress
Large surface area for immobilized enzymes
Easy product recovery
Explanation - Fluidized beds provide high surface area for enzyme attachment, enhancing biofuel conversion efficiency.
Correct answer is: Large surface area for immobilized enzymes
Q.65 In a membrane bioreactor, which parameter is most important for controlling the permeate flux?
Temperature
Pore size
Transmembrane pressure
pH
Explanation - Transmembrane pressure drives the flux across the membrane and is critical for operation.
Correct answer is: Transmembrane pressure
Q.66 Which bioreactor type is used for the production of vaccines that require adherent cell lines?
Stirred-tank
Microcarrier
Packed-bed
Wave
Explanation - Microcarriers allow adherent cell lines to grow in suspension, facilitating vaccine production.
Correct answer is: Microcarrier
Q.67 Which type of bioreactor provides a low-shear environment suitable for stem cell culture?
Stirred-tank
Airlift
Rotating Wall Vessel
Packed-bed
Explanation - The RWV offers a gentle, microgravity-like environment, ideal for delicate stem cells.
Correct answer is: Rotating Wall Vessel
Q.68 What is the primary function of the sparger in a bubble column reactor?
To stir the liquid
To introduce gas bubbles
To maintain temperature
To add nutrients
Explanation - The sparger releases gas into the liquid to promote mixing and oxygen transfer.
Correct answer is: To introduce gas bubbles
Q.69 Which bioreactor type is considered the gold standard for scale-up of recombinant protein production?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Stirred-tank reactors offer robust control over culture conditions, essential for recombinant protein yields.
Correct answer is: Stirred-tank
Q.70 In a wave bioreactor, what is typically the volume-to-surface-area ratio?
High
Low
Moderate
Variable
Explanation - Wave bioreactors maintain a low volume-to-surface-area ratio to maximize surface exposure.
Correct answer is: Low
Q.71 Which type of bioreactor uses a rotating disc to create a low-shear environment for cell growth?
Rotating Wall Vessel
Stirred-tank
Airlift
Packed-bed
Explanation - The rotating disc of a RWV mimics microgravity, providing low-shear conditions.
Correct answer is: Rotating Wall Vessel
Q.72 Which bioreactor type is best suited for the cultivation of anaerobic bacteria?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Packed-bed reactors can be designed to maintain anoxic conditions suitable for anaerobes.
Correct answer is: Packed-bed
Q.73 What is a key design parameter for a bubble column reactor?
Impeller speed
Gas flow rate
Temperature control
Wave frequency
Explanation - Gas flow rate controls bubble size and oxygen transfer in bubble column systems.
Correct answer is: Gas flow rate
Q.74 In a fluidized-bed bioreactor, what is the main advantage over a packed-bed system?
Higher pressure drop
Better mixing and mass transfer
Lower cost
Simpler design
Explanation - Fluidized beds provide uniform mixing and improved mass transfer compared to static packed beds.
Correct answer is: Better mixing and mass transfer
Q.75 Which type of bioreactor is typically used for large-scale production of monoclonal antibodies?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Microcarrier systems in stirred-tank reactors support high-density mammalian cell cultures for antibody production.
Correct answer is: Microcarrier
Q.76 What is the primary mechanism of mixing in a wave bioreactor?
Impeller agitation
Rocking motion
Gas sparging
Fluidized flow
Explanation - Wave bioreactors mix cultures by rocking the vessel, creating surface waves.
Correct answer is: Rocking motion
Q.77 Which bioreactor type is characterized by a single vertical column where gas and liquid flow through separate pathways?
Airlift
Stirred-tank
Packed-bed
Microcarrier
Explanation - The airlift reactor has distinct gas and liquid columns facilitating circulation.
Correct answer is: Airlift
Q.78 What is a significant challenge when scaling up a microcarrier bioreactor?
Maintaining cell viability
Providing sufficient oxygen
Avoiding microcarrier aggregation
Controlling temperature
Explanation - Aggregation can limit nutrient diffusion and complicate downstream processing.
Correct answer is: Avoiding microcarrier aggregation
Q.79 Which bioreactor type typically has the highest oxygen transfer rates?
Stirred-tank
Bubble column
Airlift
Packed-bed
Explanation - Stirred-tank bioreactors achieve high kLa due to efficient sparging and mechanical mixing.
Correct answer is: Stirred-tank
Q.80 In a packed-bed bioreactor, which component is crucial for ensuring even distribution of the liquid phase?
Impeller
Sparger
Distributer plate
Wave plate
Explanation - A distributor plate at the inlet helps spread the liquid evenly across the packed bed.
Correct answer is: Distributer plate
Q.81 Which type of bioreactor is best suited for the cultivation of adherent mammalian cells in a large-scale, low-shear environment?
Rotating Wall Vessel
Stirred-tank
Airlift
Packed-bed
Explanation - The RWV offers a low-shear, microgravity-like environment ideal for adherent mammalian cells.
Correct answer is: Rotating Wall Vessel
Q.82 What is the main advantage of an airlift bioreactor over a stirred-tank reactor?
Higher shear stress
Lower oxygen transfer
No mechanical agitation
Higher cost
Explanation - Airlift reactors use buoyancy-driven flow, eliminating mechanical stirrers and reducing shear.
Correct answer is: No mechanical agitation
Q.83 Which type of bioreactor is commonly used for the production of industrial enzymes using immobilized cells?
Packed-bed
Stirred-tank
Airlift
Membrane
Explanation - Packed-bed reactors provide a fixed support for immobilized cells, enhancing enzyme production.
Correct answer is: Packed-bed
Q.84 In a wave bioreactor, what is the typical maximum rocking amplitude used to avoid splashing?
2°
4°
6°
8°
Explanation - Rocking amplitudes around 4° are common to provide sufficient mixing while preventing splashing.
Correct answer is: 4°
Q.85 Which bioreactor type is most suitable for high-throughput screening of microbial strains?
Stirred-tank
Airlift
Microcarrier
Packed-bed
Explanation - Stirred-tank reactors are scalable and provide uniform conditions ideal for high-throughput assays.
Correct answer is: Stirred-tank
Q.86 Which bioreactor type uses a gas-permeable membrane to allow gas exchange while maintaining a sterile liquid phase?
Stirred-tank
Membrane bioreactor
Packed-bed
Microcarrier
Explanation - Membrane bioreactors facilitate gas transfer through a permeable membrane without contaminating the culture.
Correct answer is: Membrane bioreactor
Q.87 What is a key design consideration for an airlift bioreactor?
Impeller speed
Baffle arrangement
Gas flow distribution
Wave frequency
Explanation - Uniform gas distribution ensures efficient circulation and oxygen transfer in an airlift system.
Correct answer is: Gas flow distribution
Q.88 Which bioreactor type is most commonly used for the production of recombinant DNA viruses?
Stirred-tank
Airlift
Microcarrier
Packed-bed
Explanation - Stirred-tank reactors offer precise control of culture conditions, essential for virus replication.
Correct answer is: Stirred-tank
Q.89 In a fluidized-bed bioreactor, what is the typical range of liquid velocity required to maintain fluidization?
0.01–0.05 m/s
0.05–0.2 m/s
0.2–1.0 m/s
1.0–5.0 m/s
Explanation - Fluidization occurs within the 0.05–0.2 m/s range, balancing support of particles without causing blow-down.
Correct answer is: 0.05–0.2 m/s
Q.90 Which of the following bioreactors is best for low-cost, small-scale production of probiotics?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Airlift reactors are inexpensive, have low mechanical parts, and provide adequate mixing for probiotic cultures.
Correct answer is: Airlift
Q.91 What is the primary benefit of using a rotating disc bioreactor for cell culture?
High shear stress
Low shear stress
High oxygen transfer
Easy product recovery
Explanation - The rotating disc creates a low-shear environment, protecting sensitive cells.
Correct answer is: Low shear stress
Q.92 Which bioreactor type typically uses a single tank with no moving parts for mixing?
Bubble column
Stirred-tank
Wave
Packed-bed
Explanation - Bubble column reactors rely on gas bubbles for mixing, eliminating moving parts.
Correct answer is: Bubble column
Q.93 In a membrane bioreactor, which parameter most directly affects the rate of cell retention?
Membrane pore size
Temperature
pH
Light intensity
Explanation - The pore size determines whether cells are retained or pass through the membrane.
Correct answer is: Membrane pore size
Q.94 What is the typical operating temperature range for mammalian cell culture in a stirred-tank bioreactor?
25–30°C
30–37°C
37–40°C
40–45°C
Explanation - Mammalian cells usually grow best between 30–37°C in a controlled bioreactor environment.
Correct answer is: 30–37°C
Q.95 Which bioreactor type is best suited for high-throughput fermentation of yeast?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank reactors can be easily adapted to small-scale, high-throughput screening.
Correct answer is: Stirred-tank
Q.96 Which type of bioreactor is characterized by a rotating vessel that provides a low-shear, low-oxygen environment?
Stirred-tank
Airlift
Rotating Wall Vessel
Packed-bed
Explanation - RWV reactors mimic microgravity, creating low-shear conditions suitable for sensitive cultures.
Correct answer is: Rotating Wall Vessel
Q.97 In a bubble column reactor, what is the main driver of liquid movement?
Mechanical impeller
Gas bubbles
Waterfall effect
Rocking motion
Explanation - Rising gas bubbles cause liquid circulation in bubble column systems.
Correct answer is: Gas bubbles
Q.98 Which bioreactor type is most commonly used for the production of monoclonal antibodies in mammalian cells?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Microcarrier systems in stirred-tank bioreactors provide high surface area for adherent mammalian cells.
Correct answer is: Microcarrier
Q.99 What is the main advantage of using a packed-bed reactor for enzyme immobilization?
High shear stress
High surface area for immobilization
Low oxygen transfer
Easy product recovery
Explanation - Packed beds provide a large surface for immobilized enzymes to attach and function.
Correct answer is: High surface area for immobilization
Q.100 Which bioreactor type typically has the lowest oxygen transfer rate among the options listed?
Stirred-tank
Airlift
Packed-bed
Wave
Explanation - Packed-bed reactors often exhibit lower kLa due to limited gas-liquid contact.
Correct answer is: Packed-bed
Q.101 In a membrane bioreactor, what is the purpose of the permeate?
To supply nutrients
To remove waste
To supply oxygen
To remove cells
Explanation - The permeate is the clear liquid that passes through the membrane, free of cells.
Correct answer is: To remove cells
Q.102 Which type of bioreactor provides a low-shear environment suitable for stem cell culture?
Stirred-tank
Airlift
Rotating Wall Vessel
Packed-bed
Explanation - The RWV mimics microgravity, reducing shear forces on stem cells.
Correct answer is: Rotating Wall Vessel
Q.103 Which bioreactor type typically uses a rotating disc to create a microgravity environment for cells?
Rotating Wall Vessel
Stirred-tank
Airlift
Packed-bed
Explanation - The rotating disc of the RWV provides a low-shear, low-oxygen environment.
Correct answer is: Rotating Wall Vessel
Q.104 What is the main advantage of a wave bioreactor for scale-up of cell cultures?
High shear stress
Low shear stress
High oxygen transfer rate
Large footprint
Explanation - Wave bioreactors maintain gentle mixing, enabling larger volumes without damaging cells.
Correct answer is: Low shear stress
Q.105 Which type of bioreactor uses a gas-permeable membrane to provide oxygen without mechanical agitation?
Stirred-tank
Airlift
Membrane bioreactor
Packed-bed
Explanation - The membrane allows oxygen diffusion directly into the culture while preventing mixing.
Correct answer is: Membrane bioreactor
Q.106 In a bubble column reactor, which parameter is critical for controlling gas distribution?
Impeller speed
Gas flow rate
Temperature
pH
Explanation - Gas flow rate determines bubble size and distribution, affecting oxygen transfer.
Correct answer is: Gas flow rate
Q.107 Which bioreactor type is commonly used for the production of recombinant proteins in yeast?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank bioreactors provide the necessary control over temperature and aeration for yeast cultures.
Correct answer is: Stirred-tank
Q.108 What is a key disadvantage of a packed-bed bioreactor for large-scale production?
Low oxygen transfer
High shear stress
High capital cost
Large footprint
Explanation - Packed beds often suffer from limited oxygen transfer, limiting cell growth at large scale.
Correct answer is: Low oxygen transfer
Q.109 Which bioreactor type is best suited for continuous fermentation of lactic acid bacteria?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank reactors allow precise control of pH and oxygen for continuous processes.
Correct answer is: Stirred-tank
Q.110 In a microcarrier bioreactor, what is the main factor influencing cell attachment?
Impeller speed
Surface chemistry of carriers
Gas flow rate
Light intensity
Explanation - The chemical properties of microcarriers affect how well cells can attach and grow.
Correct answer is: Surface chemistry of carriers
Q.111 Which type of bioreactor provides a high surface-to-volume ratio for cell attachment in suspension culture?
Microcarrier
Stirred-tank
Airlift
Packed-bed
Explanation - Microcarriers dramatically increase available surface area for adherent cells.
Correct answer is: Microcarrier
Q.112 In a wave bioreactor, which parameter primarily limits the maximum cell density?
Oxygen transfer
Shear stress
Nutrient limitation
Temperature control
Explanation - The low kLa of wave bioreactors limits how many cells can be supported at high densities.
Correct answer is: Oxygen transfer
Q.113 Which bioreactor type is most commonly used for the production of monoclonal antibodies at industrial scale?
Microcarrier in stirred-tank
Stirred-tank alone
Airlift
Packed-bed
Explanation - The combination provides high cell density and excellent oxygen transfer for antibody production.
Correct answer is: Microcarrier in stirred-tank
Q.114 What is the primary mode of mixing in a packed-bed bioreactor?
Impeller agitation
Bubbles rising through the bed
Wave motion
Rotating disc
Explanation - Liquid and gas bubbles provide mixing by rising through the packed bed.
Correct answer is: Bubbles rising through the bed
Q.115 Which bioreactor type is best suited for the cultivation of anaerobic microbes?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - Packed-bed reactors can be operated anaerobically and provide a stable environment for anaerobes.
Correct answer is: Packed-bed
Q.116 In a bubble column reactor, which design element influences bubble size?
Sparger diameter
Temperature
pH
Light intensity
Explanation - The sparger hole size determines the size of bubbles released into the column.
Correct answer is: Sparger diameter
Q.117 Which bioreactor type typically has the highest shear stress among the options listed?
Stirred-tank
Airlift
Wave
Packed-bed
Explanation - Mechanical impellers in stirred-tank reactors generate the highest shear forces.
Correct answer is: Stirred-tank
Q.118 What is a key design consideration for scaling up a microcarrier bioreactor?
Maintaining low shear
Increasing oxygen transfer
Preventing microcarrier aggregation
Reducing temperature
Explanation - Aggregation can reduce effective surface area and hinder product recovery.
Correct answer is: Preventing microcarrier aggregation
Q.119 Which bioreactor type is best suited for large-scale production of vaccines using mammalian cell lines?
Stirred-tank with microcarriers
Airlift
Packed-bed
Wave
Explanation - Stirred-tank systems with microcarriers provide high cell densities and good control for vaccine production.
Correct answer is: Stirred-tank with microcarriers
Q.120 What is the main benefit of an airlift bioreactor in bioprocessing?
High oxygen transfer rate
Low shear stress
High pressure drop
Low cost of operation
Explanation - Airlift reactors avoid mechanical agitators, reducing shear stress on sensitive cells.
Correct answer is: Low shear stress
Q.121 Which type of bioreactor typically requires a distributor plate to ensure even liquid flow?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - A distributor plate at the inlet of a packed-bed distributes liquid uniformly across the bed.
Correct answer is: Packed-bed
Q.122 In a fluidized-bed bioreactor, which phenomenon helps enhance mass transfer?
Shear-induced turbulence
Gas-liquid contact
Particle fluidization
Light scattering
Explanation - Fluidization of particles creates a highly mixed environment, improving mass transfer.
Correct answer is: Particle fluidization
Q.123 Which bioreactor type is most suitable for the cultivation of algae in photobioreactors?
Airlift
Stirred-tank
Packed-bed
Wave
Explanation - Airlift reactors provide gentle mixing and efficient gas exchange, ideal for algae.
Correct answer is: Airlift
Q.124 Which bioreactor type typically has the lowest oxygen transfer rate in large scale?
Stirred-tank
Packed-bed
Airlift
Wave
Explanation - Packed beds limit gas-liquid contact, resulting in lower kLa compared to other types.
Correct answer is: Packed-bed
Q.125 What is the primary advantage of using a wave bioreactor for stem cell expansion?
High shear stress
Low shear stress
High oxygen transfer
Large footprint
Explanation - The gentle rocking motion in wave bioreactors protects fragile stem cells.
Correct answer is: Low shear stress
Q.126 Which bioreactor type is commonly used for the production of recombinant enzymes using immobilized cells?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - Packed-bed reactors provide a surface for immobilized cells to attach, enhancing enzyme production.
Correct answer is: Packed-bed
Q.127 What is a key challenge when scaling up a microcarrier bioreactor?
Maintaining low shear
Preventing aggregation
Increasing oxygen transfer
Reducing temperature
Explanation - Aggregation can limit mass transfer and complicate downstream processing.
Correct answer is: Preventing aggregation
Q.128 Which bioreactor type typically requires no mechanical agitators for mixing?
Airlift
Stirred-tank
Wave
Packed-bed
Explanation - Airlift reactors use buoyancy-driven flow, eliminating the need for mechanical stirrers.
Correct answer is: Airlift
Q.129 In a bubble column reactor, what is the typical range of gas flow rate for optimal mixing?
0.01–0.05 L/min
0.05–0.2 L/min
0.2–1.0 L/min
1.0–5.0 L/min
Explanation - This range balances adequate bubble production with manageable gas-liquid contact.
Correct answer is: 0.05–0.2 L/min
Q.130 Which bioreactor type is best suited for continuous fermentation of lactic acid bacteria?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank reactors provide precise control of pH and oxygen for continuous processes.
Correct answer is: Stirred-tank
Q.131 What is a major disadvantage of a wave bioreactor for high-density mammalian cell culture?
Low oxygen transfer
High shear stress
Complex operation
High cost
Explanation - Wave bioreactors generally have lower kLa values, limiting cell density.
Correct answer is: Low oxygen transfer
Q.132 Which bioreactor type is commonly used for the production of recombinant proteins in yeast?
Stirred-tank
Airlift
Packed-bed
Microcarrier
Explanation - Stirred-tank reactors provide robust control of temperature and aeration for yeast cultures.
Correct answer is: Stirred-tank
Q.133 What is the primary function of a gas sparger in a bubble column bioreactor?
To stir the liquid
To introduce gas bubbles
To maintain temperature
To add nutrients
Explanation - The sparger releases gas into the liquid to promote mixing and oxygen transfer.
Correct answer is: To introduce gas bubbles
Q.134 Which bioreactor type is most suitable for the production of monoclonal antibodies in mammalian cell lines?
Stirred-tank with microcarriers
Stirred-tank alone
Airlift
Packed-bed
Explanation - This configuration allows high cell density and good oxygen transfer for antibody production.
Correct answer is: Stirred-tank with microcarriers
Q.135 What is the main advantage of a rotating wall vessel (RWV) for cell culture?
High shear stress
Low shear stress
High oxygen transfer
Large footprint
Explanation - The RWV provides a low-shear, microgravity-like environment ideal for sensitive cells.
Correct answer is: Low shear stress
Q.136 In which bioreactor type is cell recovery generally more difficult due to cell attachment to the reactor wall?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - Packed-bed reactors trap cells in the fixed bed, complicating harvesting.
Correct answer is: Packed-bed
Q.137 Which bioreactor type is best suited for the cultivation of anaerobic fungi?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - Packed-bed reactors can be operated under anaerobic conditions suitable for fungi.
Correct answer is: Packed-bed
Q.138 Which bioreactor type typically requires a distributor plate to ensure even liquid distribution?
Packed-bed
Stirred-tank
Airlift
Microcarrier
Explanation - The distributor plate at the inlet of a packed-bed ensures uniform liquid flow across the bed.
Correct answer is: Packed-bed
Q.139 What is the main disadvantage of using a packed-bed bioreactor for large-scale production?
Low oxygen transfer
High shear stress
Low capital cost
Large footprint
Explanation - Limited gas-liquid contact in packed beds restricts oxygen availability at scale.
Correct answer is: Low oxygen transfer
Q.140 Which bioreactor type is most commonly used for the production of recombinant proteins in mammalian cell cultures?
Stirred-tank with microcarriers
Stirred-tank alone
Airlift
Packed-bed
Explanation - Stirred-tank reactors with microcarriers provide high surface area for adherent mammalian cells.
Correct answer is: Stirred-tank with microcarriers