Q.1 What is a bioreactor?
A chemical reactor that produces electricity
A vessel that supports growth of biological cells or organisms
A type of battery
A computer processor
Explanation - A bioreactor is a closed system designed to provide optimal conditions for biological organisms to grow or produce desired products.
Correct answer is: A vessel that supports growth of biological cells or organisms
Q.2 Which of the following is a common microorganism used in bioreactors?
E. coli
Penicillin
Iron
Oxygen
Explanation - E. coli is a widely used bacterium for producing proteins and other biochemicals in bioreactors.
Correct answer is: E. coli
Q.3 What is the primary purpose of a bioreactor?
To generate electricity from fuel cells
To produce biological products like proteins or vaccines
To store water for irrigation
To cool down electronic circuits
Explanation - Bioreactors cultivate living cells to produce pharmaceuticals, enzymes, or other bio-products.
Correct answer is: To produce biological products like proteins or vaccines
Q.4 Which type of bioreactor uses a shaking motion to keep cells suspended?
Stirred Tank
Airlift
Shaking Flask
Microcarrier
Explanation - Stirred tank bioreactors mix contents mechanically, ensuring uniform distribution of cells and nutrients.
Correct answer is: Stirred Tank
Q.5 What component of a bioreactor maintains the temperature?
Inertial stirrer
Heat exchanger
Light source
Pressure gauge
Explanation - Heat exchangers transfer heat between the reactor and a coolant to regulate temperature.
Correct answer is: Heat exchanger
Q.6 Which sensor is commonly used to measure dissolved oxygen in a bioreactor?
pH probe
Oxygen sensor
Thermocouple
Pressure transducer
Explanation - Dissolved oxygen sensors monitor oxygen levels critical for aerobic cell growth.
Correct answer is: Oxygen sensor
Q.7 What parameter indicates the acidity or alkalinity of the bioreactor medium?
Temperature
pH
Dissolved oxygen
Viscosity
Explanation - pH measures hydrogen ion concentration, affecting enzyme activity and cell metabolism.
Correct answer is: pH
Q.8 Which of the following is NOT typically a control variable in a bioreactor?
Agitation speed
Nutrient feed rate
Lighting intensity
Temperature
Explanation - Bioreactors usually do not rely on light except for photosynthetic cultures; other parameters are actively controlled.
Correct answer is: Lighting intensity
Q.9 What is the function of a gas sparger in a bioreactor?
To measure temperature
To introduce gases like CO₂ or O₂
To stir the medium
To filter contaminants
Explanation - A sparger disperses gas bubbles into the liquid, improving mass transfer of oxygen or carbon dioxide.
Correct answer is: To introduce gases like CO₂ or O₂
Q.10 Which of these materials is commonly used for the construction of bioreactor vessels?
PVC
Stainless steel
Aluminum
Concrete
Explanation - Stainless steel resists corrosion, is sterilizable, and is standard in bioprocess equipment.
Correct answer is: Stainless steel
Q.11 In a stirred-tank bioreactor, what is the main purpose of the impeller?
To heat the culture
To maintain uniform mixing
To measure pressure
To filter solids
Explanation - The impeller agitates the liquid, ensuring cells receive nutrients and gases evenly.
Correct answer is: To maintain uniform mixing
Q.12 Which parameter is critical for the growth of aerobic microorganisms?
Dissolved oxygen
Nutrient concentration
Light intensity
Magnetic field strength
Explanation - Aerobic microbes require oxygen for respiration; low levels can limit growth.
Correct answer is: Dissolved oxygen
Q.13 What is the role of a feed pump in a bioreactor?
To remove waste gases
To add nutrients or media
To cool the reactor
To sterilize the culture
Explanation - Feed pumps deliver fresh nutrients or media to sustain cell growth during fed-batch operations.
Correct answer is: To add nutrients or media
Q.14 Which term describes the growth phase where cell division is fastest?
Lag phase
Log phase
Stationary phase
Death phase
Explanation - During the log (exponential) phase, cells divide rapidly, doubling at a constant rate.
Correct answer is: Log phase
Q.15 Which instrument would you use to measure the pH of a bioreactor culture?
pH meter
Thermometer
Spectrophotometer
Anemometer
Explanation - A pH meter provides precise readings of the medium’s acidity or alkalinity.
Correct answer is: pH meter
Q.16 Why is sterilization important in a bioreactor?
To improve mixing
To prevent contamination
To increase temperature
To reduce electricity usage
Explanation - Sterilization eliminates unwanted organisms that could outcompete or spoil the intended culture.
Correct answer is: To prevent contamination
Q.17 Which of these is an example of a fed-batch bioprocess?
Continuous feeding of fresh medium
Adding nutrients over time to a batch culture
Removing all cells after growth
Stirring without adding anything
Explanation - Fed-batch adds nutrients incrementally, extending growth beyond the initial batch phase.
Correct answer is: Adding nutrients over time to a batch culture
Q.18 What is the main advantage of a perfusion bioreactor over a batch system?
Higher oxygen transfer rate
Continuous removal of waste and addition of fresh media
Lower cost
Simpler control
Explanation - Perfusion maintains steady-state conditions and can achieve higher cell densities.
Correct answer is: Continuous removal of waste and addition of fresh media
Q.19 Which of the following best describes a wave bioreactor?
A reactor that uses a rotating wave to mix
A reactor with a wave-shaped impeller
A reactor that relies on microbubbles
A reactor with a wave of electric current
Explanation - Wave bioreactors employ rocking motions to create gentle mixing and oxygen transfer.
Correct answer is: A reactor that uses a rotating wave to mix
Q.20 How does a bioreactor’s agitation speed affect oxygen transfer?
Higher speed decreases transfer
Higher speed increases transfer
Speed has no effect
Speed only affects temperature
Explanation - Increased agitation improves mixing and surface area for gas exchange.
Correct answer is: Higher speed increases transfer
Q.21 Which of these is a key design criterion for scaling up a bioreactor?
Keeping the same volume
Maintaining the same power input per volume
Changing the shape completely
Using a different material
Explanation - Power input per volume is used to preserve mixing and shear conditions when scaling.
Correct answer is: Maintaining the same power input per volume
Q.22 What is the purpose of a bioreactor’s off-gas monitoring system?
To measure CO₂ and O₂ levels
To sterilize the air
To keep temperature constant
To add nutrients
Explanation - Monitoring gases informs on metabolic activity and allows process adjustments.
Correct answer is: To measure CO₂ and O₂ levels
Q.23 In a fed-batch process, which parameter is typically monitored to decide when to add feed?
Cell density
pH level
Temperature
Light intensity
Explanation - As cell density rises, nutrient demand increases; feed addition is triggered by density or metabolite levels.
Correct answer is: Cell density
Q.24 What is the significance of the Reynolds number in bioreactor design?
It predicts gas flow velocity
It indicates mixing regime (laminar vs turbulent)
It measures temperature
It calculates power consumption
Explanation - Reynolds number helps assess flow characteristics, influencing mixing and shear stress.
Correct answer is: It indicates mixing regime (laminar vs turbulent)
Q.25 Which component of a bioreactor is responsible for sterility?
Baffle plates
Sterilization jacket
Agitator blade
Inert gas inlet
Explanation - The jacket supplies hot steam or chemicals to sterilize the vessel interior.
Correct answer is: Sterilization jacket
Q.26 Which of the following is a typical product produced in a bioreactor?
Polystyrene beads
Insulin
Steel rods
Photovoltaic cells
Explanation - Bioreactors are used to produce insulin via recombinant DNA technology.
Correct answer is: Insulin
Q.27 Why is mixing important in a bioreactor?
To keep temperature constant
To ensure uniform nutrient distribution and gas exchange
To reduce power usage
To sterilize the medium
Explanation - Mixing eliminates concentration gradients, improving cell growth and product yield.
Correct answer is: To ensure uniform nutrient distribution and gas exchange
Q.28 What is the role of a baffle in a stirred tank bioreactor?
To increase mixing efficiency
To reduce power input
To control temperature
To measure pH
Explanation - Baffles disrupt vortex formation, improving turbulence and mixing.
Correct answer is: To increase mixing efficiency
Q.29 Which parameter is directly affected by changing the impeller speed?
Oxygen transfer rate
Light intensity
Magnetic field
Electric potential
Explanation - Higher impeller speeds increase turbulence, enhancing oxygen dissolution.
Correct answer is: Oxygen transfer rate
Q.30 Which sensor would you use to measure the pressure inside a bioreactor?
Pressure transducer
Thermocouple
pH probe
Oxygen sensor
Explanation - Pressure transducers convert pressure into electrical signals for monitoring.
Correct answer is: Pressure transducer
Q.31 What is the main difference between batch and continuous bioreactors?
Batch uses electricity, continuous does not
Continuous adds fresh medium while batch does not
Batch has a fixed volume; continuous does not
Batch is for plants, continuous is for animals
Explanation - Continuous systems maintain constant operation with continuous feed and harvest.
Correct answer is: Continuous adds fresh medium while batch does not
Q.32 Which type of bioreactor is commonly used for large-scale yeast fermentation?
Stirred tank
Packed bed
Airlift
Microcarrier
Explanation - Stirred tanks provide high oxygen transfer rates suitable for yeast growth.
Correct answer is: Stirred tank
Q.33 What is the primary function of a temperature probe in a bioreactor?
Measure nutrient concentration
Detect oxygen levels
Record temperature changes
Count cell density
Explanation - Temperature probes monitor the culture temperature to maintain optimal conditions.
Correct answer is: Record temperature changes
Q.34 Which control strategy is often used to maintain dissolved oxygen levels?
Open-loop control
PID control
Manual adjustment only
Random sampling
Explanation - PID controllers adjust aeration and agitation based on oxygen sensor feedback.
Correct answer is: PID control
Q.35 In bioreactor design, what is the purpose of a gas sparger plate?
To heat the liquid
To evenly disperse gas bubbles
To stir the culture
To filter the medium
Explanation - The sparger plate increases gas-liquid contact, enhancing oxygen transfer.
Correct answer is: To evenly disperse gas bubbles
Q.36 Which of the following is NOT a typical bioreactor medium component?
Glucose
Yeast extract
Silicon dioxide
Mineral salts
Explanation - Silicon dioxide is not commonly used in microbial culture media.
Correct answer is: Silicon dioxide
Q.37 What does the term 'bioreactor' imply about the contents inside?
It contains only metal
It contains living cells or organisms
It stores chemicals
It generates electricity
Explanation - Bioreactors support biological processes using living cells.
Correct answer is: It contains living cells or organisms
Q.38 Which parameter is typically measured in a bioreactor to gauge cell metabolism?
Electric current
Glucose concentration
Wind speed
Light intensity
Explanation - Glucose consumption indicates metabolic activity and cell growth.
Correct answer is: Glucose concentration
Q.39 Why is the impeller design important in a bioreactor?
It affects heat transfer only
It influences mixing and shear stress
It determines the color of the medium
It controls the pH directly
Explanation - Impeller shape and speed affect turbulence, which impacts cell viability.
Correct answer is: It influences mixing and shear stress
Q.40 Which type of bioreactor uses a rotating magnetic field for stirring?
Stirred tank
Magnetic stirrer
Airlift
Wave bioreactor
Explanation - Magnetic stirrers embed a magnetic stir bar within the culture, avoiding impellers.
Correct answer is: Magnetic stirrer
Q.41 What is the main advantage of using a wave bioreactor?
It provides high shear
It offers gentle mixing and low oxygen transfer rates
It is very expensive
It requires no control
Explanation - Wave bioreactors are suitable for shear-sensitive cells like mammalian cells.
Correct answer is: It offers gentle mixing and low oxygen transfer rates
Q.42 Which of the following best describes a perfusion bioreactor?
A reactor with continuous flow of fresh medium and removal of waste
A batch reactor that is never turned off
A reactor that uses air only for oxygenation
A reactor that does not require mixing
Explanation - Perfusion systems maintain steady-state conditions for high cell density cultures.
Correct answer is: A reactor with continuous flow of fresh medium and removal of waste
Q.43 Which parameter is directly influenced by the agitator speed?
Power consumption
Light intensity
Magnetic field
Cell size
Explanation - Higher speeds increase power usage due to higher hydrodynamic resistance.
Correct answer is: Power consumption
Q.44 In a stirred tank, what is the function of the baffle?
To block gas from entering
To promote mixing and reduce vortex formation
To measure temperature
To sterilize the medium
Explanation - Baffles break up swirling motion, improving turbulence and mixing uniformity.
Correct answer is: To promote mixing and reduce vortex formation
Q.45 Which of these is an example of a gas used for oxygenation in a bioreactor?
Nitrogen
Oxygen
Carbon Dioxide
Helium
Explanation - Oxygen gas is sparged to provide the required dissolved oxygen for aerobic cells.
Correct answer is: Oxygen
Q.46 What does a dissolved oxygen probe measure?
The amount of oxygen dissolved in the liquid
The temperature of the liquid
The pH of the liquid
The electrical conductivity
Explanation - Dissolved oxygen probes monitor oxygen levels to ensure cells receive enough oxygen.
Correct answer is: The amount of oxygen dissolved in the liquid
Q.47 Which of the following is a key design consideration for small-scale bioreactors?
Cost of materials
Electricity usage only
Color of the vessel
None of the above
Explanation - Budget constraints are critical in designing small-scale bioreactors for research.
Correct answer is: Cost of materials
Q.48 What is the typical range of temperatures used for mammalian cell culture?
4-10°C
25-30°C
37-40°C
60-70°C
Explanation - Mammalian cells thrive near body temperature, usually between 37°C and 40°C.
Correct answer is: 37-40°C
Q.49 Which component of a bioreactor is responsible for controlling the agitation speed?
Stirrer motor
Temperature probe
pH sensor
Pressure transducer
Explanation - The motor drives the stirrer to set agitation speed for mixing.
Correct answer is: Stirrer motor
Q.50 Which of the following is an example of a control loop used in bioreactor operations?
Proportional-Integral-Derivative (PID) loop
Manual adjustment loop
Random control loop
No loop at all
Explanation - PID controllers automatically adjust inputs like aeration based on sensor feedback.
Correct answer is: Proportional-Integral-Derivative (PID) loop
Q.51 What is the purpose of the sterilization jacket in a bioreactor?
To provide electric power
To sterilize the vessel using steam
To measure temperature
To add nutrients
Explanation - The jacket circulates hot steam, sterilizing the internal surfaces before use.
Correct answer is: To sterilize the vessel using steam
Q.52 Which of these is NOT a typical gas used in bioreactor aeration?
Oxygen
Nitrogen
Carbon Dioxide
Helium
Explanation - Helium is rarely used for aeration due to low solubility and lack of metabolic role.
Correct answer is: Helium
Q.53 Which of the following best describes a fed-batch operation?
The culture is fed continuously at a constant rate
The culture is fed intermittently to maintain substrate levels
No nutrients are added during operation
The culture is completely sealed with no gas exchange
Explanation - Fed-batch adds nutrients in pulses or gradually to control growth and product formation.
Correct answer is: The culture is fed intermittently to maintain substrate levels
Q.54 What is the main challenge when scaling up a bioreactor from lab to industrial size?
Maintaining consistent temperature
Ensuring uniform mixing and shear conditions
Changing the color of the vessel
Adding more lights
Explanation - Scaling up can alter flow patterns; preserving hydrodynamics is essential for process consistency.
Correct answer is: Ensuring uniform mixing and shear conditions
Q.55 Which sensor is typically used to monitor temperature in a bioreactor?
Thermocouple
pH probe
Oxygen sensor
Pressure sensor
Explanation - Thermocouples provide accurate temperature readings critical for cell growth.
Correct answer is: Thermocouple
Q.56 In a bioreactor, what is the effect of increasing agitation speed on shear stress?
Shear stress decreases
Shear stress increases
Shear stress remains unchanged
Shear stress becomes zero
Explanation - Higher agitation produces greater shear forces, which can damage shear-sensitive cells.
Correct answer is: Shear stress increases
Q.57 Which of the following is a typical purpose of a pH controller in a bioreactor?
To maintain cell viability by regulating acidity
To heat the medium
To stir the culture
To measure dissolved oxygen
Explanation - pH affects enzyme activity and cell metabolism, so it is tightly controlled.
Correct answer is: To maintain cell viability by regulating acidity
Q.58 What is the main difference between a stirred-tank and an airlift bioreactor?
Stirred tanks use mechanical stirring; airlifts use buoyancy-driven flow
Stirred tanks are used for plants only
Airlifts have no impellers
They are identical in design
Explanation - Stirred tanks mix mechanically, while airlifts rely on gas bubbles to generate circulation.
Correct answer is: Stirred tanks use mechanical stirring; airlifts use buoyancy-driven flow
Q.59 Which parameter is NOT typically measured in a standard bioreactor process?
Dissolved oxygen
pH
Cell density
Ambient light intensity
Explanation - Light intensity is irrelevant unless phototrophic organisms are grown.
Correct answer is: Ambient light intensity
Q.60 Why is sterilization important before starting a bioreactor run?
To improve mixing speed
To eliminate unwanted microbes that could contaminate the culture
To increase oxygen transfer
To reduce electricity consumption
Explanation - Contamination can outcompete the intended culture, ruining the batch.
Correct answer is: To eliminate unwanted microbes that could contaminate the culture
Q.61 What does a bioreactor’s gas inlet typically deliver?
CO₂ only
O₂ or air
Water vapor
Nitrogen only
Explanation - Aerobic cultures require oxygen or air for respiration.
Correct answer is: O₂ or air
Q.62 Which of the following is a typical indicator of cell metabolic activity in a bioreactor?
Glucose consumption
Light intensity
Temperature changes only
Pressure fluctuations only
Explanation - Glucose uptake is directly linked to cell metabolism and growth.
Correct answer is: Glucose consumption
Q.63 Which of the following is a benefit of using a wave bioreactor for mammalian cells?
High shear stress
Gentle mixing and low oxygen transfer
High temperature
No gas exchange
Explanation - Wave bioreactors provide gentle agitation, preserving fragile mammalian cells.
Correct answer is: Gentle mixing and low oxygen transfer
Q.64 In a continuous bioreactor, what is typically removed from the reactor?
Cells only
Products and waste only
Fresh medium only
Both product and cells, while fresh medium is added
Explanation - Continuous systems maintain a steady-state by constantly adding and removing material.
Correct answer is: Both product and cells, while fresh medium is added
Q.65 What is the purpose of a bioreactor’s agitation system?
To cool down the culture
To provide uniform mixing and oxygen transfer
To increase pressure
To sterilize the medium
Explanation - Agitation ensures even distribution of nutrients, cells, and gases.
Correct answer is: To provide uniform mixing and oxygen transfer
Q.66 Which sensor measures the pH value inside a bioreactor?
pH probe
Temperature probe
Pressure sensor
Oxygen sensor
Explanation - pH probes directly measure hydrogen ion concentration in the culture medium.
Correct answer is: pH probe
Q.67 What is a typical target range for dissolved oxygen in many bioprocesses?
0-5%
5-10%
10-20%
20-30%
Explanation - Oxygen levels between 5% and 10% are commonly maintained for aerobic cultures.
Correct answer is: 5-10%
Q.68 Which component in a bioreactor is used to measure pressure differential?
Pressure transducer
Temperature probe
pH probe
Oxygen sensor
Explanation - Pressure transducers convert mechanical pressure differences into electrical signals.
Correct answer is: Pressure transducer
Q.69 What is the effect of increasing dissolved oxygen levels in an aerobic bioreactor?
It can increase cell growth up to a point
It decreases cell growth
It has no effect
It always kills the cells
Explanation - Higher dissolved oxygen supports respiration but can also cause oxidative stress if too high.
Correct answer is: It can increase cell growth up to a point
Q.70 What type of control is typically used to keep temperature constant in a bioreactor?
Open-loop
Closed-loop with temperature sensor
Manual control only
No control required
Explanation - Temperature sensors provide feedback for automatic heating or cooling.
Correct answer is: Closed-loop with temperature sensor
Q.71 Which of the following is NOT typically a component of a stirred-tank bioreactor?
Impeller
Baffles
Light source
Aeration inlet
Explanation - Stirred-tank bioreactors generally do not require light unless growing photosynthetic cells.
Correct answer is: Light source
Q.72 What is a typical use for a perfusion bioreactor?
High-volume protein production with continuous cell harvesting
Small-scale single-use experiments
Drying of biomass
Electrical power generation
Explanation - Perfusion allows sustained high-density cultures and continuous product collection.
Correct answer is: High-volume protein production with continuous cell harvesting
Q.73 What is the role of a baffle in a bioreactor?
Increase mixing efficiency and reduce vortex formation
Reduce temperature
Sterilize the medium
Measure pH
Explanation - Baffles interrupt swirling motion, enhancing turbulence and mixing.
Correct answer is: Increase mixing efficiency and reduce vortex formation
Q.74 Which of the following is an example of a sensor used in bioprocess monitoring?
Thermometer
Oxygen sensor
Anemometer
Barometer
Explanation - Oxygen sensors measure dissolved oxygen critical for aerobic processes.
Correct answer is: Oxygen sensor
Q.75 Which of these is a common material used for constructing a bioreactor vessel?
Glass
Stainless steel
PVC
All of the above
Explanation - Bioreactors can be made from various materials depending on the application.
Correct answer is: All of the above
Q.76 Which of the following is a typical sensor in a bioreactor?
pH probe
Light meter
Sound detector
Wind speed gauge
Explanation - pH probes monitor acidity, essential for cell culture conditions.
Correct answer is: pH probe
Q.77 What is the purpose of a sparger in a bioreactor?
Introduce gas bubbles for oxygen transfer
Filter the medium
Heat the culture
Measure pressure
Explanation - Spargers distribute gas into the liquid to enhance oxygen dissolution.
Correct answer is: Introduce gas bubbles for oxygen transfer
Q.78 Which parameter is most directly affected by changing the agitation speed?
Oxygen transfer rate
Light intensity
Magnetic field
Electrical voltage
Explanation - Higher agitation increases turbulence, boosting gas transfer into the liquid.
Correct answer is: Oxygen transfer rate
Q.79 What is a common method for sterilizing a bioreactor before use?
Sterile filtration
Steam sterilization
UV light only
Dry heat only
Explanation - Steam provides high temperature and pressure to kill microorganisms.
Correct answer is: Steam sterilization
Q.80 Which of the following is not typically monitored in a bioreactor?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is generally not monitored unless photosynthetic organisms are grown.
Correct answer is: Light intensity
Q.81 Which of the following best describes the function of a baffle in a stirred tank?
Reduces vortex formation
Increases temperature
Provides structural support
Measures pH
Explanation - Baffles promote turbulence, improving mixing and reducing shear at the center.
Correct answer is: Reduces vortex formation
Q.82 What is a typical feed rate control strategy in a fed-batch bioreactor?
Constant feed rate
Glucose concentration based feed
No feed
Random feed schedule
Explanation - Feed is often triggered by monitoring substrate concentration to avoid depletion.
Correct answer is: Glucose concentration based feed
Q.83 Which of the following is a common product produced in bioreactors?
Vaccine
Concrete
Insulin
Batteries
Explanation - Bioreactors are used to produce various biopharmaceuticals, including vaccines.
Correct answer is: Vaccine
Q.84 What does a PID controller do in a bioreactor system?
Adjusts inputs like temperature or oxygen based on error
Measures cell density only
Operates the motor only
None of the above
Explanation - PID controllers automatically correct deviations from setpoints in process variables.
Correct answer is: Adjusts inputs like temperature or oxygen based on error
Q.85 Which of these is a key advantage of using a wave bioreactor?
High shear environment
Low shear and gentle mixing
High oxygen transfer
Large scale only
Explanation - Wave bioreactors are ideal for sensitive mammalian cells due to gentle mixing.
Correct answer is: Low shear and gentle mixing
Q.86 Which type of bioreactor uses a rotating motion to create mixing?
Stirred tank
Wave bioreactor
Airlift
Microcarrier
Explanation - Wave bioreactors rely on rocking motion to induce fluid movement.
Correct answer is: Wave bioreactor
Q.87 What is the main reason to use a gas sparger in a bioreactor?
To create turbulence for mixing
To introduce gas for oxygen transfer
To reduce temperature
To add nutrients
Explanation - Gas spargers disperse gas bubbles, improving gas-liquid mass transfer.
Correct answer is: To introduce gas for oxygen transfer
Q.88 Which of the following is an example of an operating parameter in a bioreactor?
Temperature
Color
Sound level
Wind speed
Explanation - Operating parameters include temperature, pH, dissolved oxygen, agitation speed, etc.
Correct answer is: Temperature
Q.89 Which component of a bioreactor provides heat for sterilization?
Steam jacket
Cooling coils
Light bulb
Pressure gauge
Explanation - A steam jacket circulates hot steam to sterilize the vessel before use.
Correct answer is: Steam jacket
Q.90 Which of the following best describes a fed-batch process?
Adding fresh nutrients intermittently during the batch operation
Removing all cells at once
No feeding at all
Continuous feed only
Explanation - Fed-batch involves feeding nutrients to extend growth without fully continuous operation.
Correct answer is: Adding fresh nutrients intermittently during the batch operation
Q.91 Which of the following is used to measure dissolved oxygen in a bioreactor?
Oxygen probe
Temperature probe
Pressure sensor
pH probe
Explanation - An oxygen probe monitors dissolved oxygen levels for process control.
Correct answer is: Oxygen probe
Q.92 Which of the following is NOT typically a component of a stirred-tank bioreactor?
Impeller
Baffles
Light source
Aeration inlet
Explanation - Stirred tanks rarely use light unless specifically required for phototrophic cultures.
Correct answer is: Light source
Q.93 Which of the following is a typical use for a bioreactor in industrial settings?
Production of vaccines
Manufacturing of steel
Food seasoning
Solar panel fabrication
Explanation - Bioreactors are crucial for producing biopharmaceuticals such as vaccines.
Correct answer is: Production of vaccines
Q.94 What is the main function of the agitator in a bioreactor?
Mixing the culture for uniform distribution
Measuring pH
Providing power supply
Stirring the air only
Explanation - Agitators ensure cells, nutrients, and gases are evenly distributed.
Correct answer is: Mixing the culture for uniform distribution
Q.95 Which component of a bioreactor is used to monitor temperature?
Thermocouple
pH probe
Oxygen sensor
Pressure gauge
Explanation - Thermocouples provide accurate temperature readings essential for cell growth.
Correct answer is: Thermocouple
Q.96 Which of the following is a key parameter for scaling up a bioreactor?
Maintaining same power input per volume
Changing shape randomly
Using a different material
Increasing size only
Explanation - Scaling often relies on preserving hydrodynamic conditions, such as power per volume.
Correct answer is: Maintaining same power input per volume
Q.97 Which of the following best describes a perfusion bioreactor?
Continuous removal of culture and addition of fresh medium
Batch process with no feed
Open system with no control
Dry fermentation only
Explanation - Perfusion maintains a steady state by continuously perfusing the culture.
Correct answer is: Continuous removal of culture and addition of fresh medium
Q.98 Which type of bioreactor uses a rocking motion to mix the culture?
Wave bioreactor
Stirred tank
Airlift
Packed bed
Explanation - Wave bioreactors rock to generate gentle mixing and gas transfer.
Correct answer is: Wave bioreactor
Q.99 What is the purpose of the sterilization jacket on a bioreactor?
Sterilize the vessel using hot steam
Provide cooling only
Add nutrients
Measure oxygen
Explanation - The jacket circulates steam to sterilize the interior of the reactor.
Correct answer is: Sterilize the vessel using hot steam
Q.100 What is a common method for measuring cell density in a bioreactor?
Optical density at 600 nm
Light intensity
Temperature
Pressure
Explanation - OD600 is a quick way to estimate cell concentration in liquid cultures.
Correct answer is: Optical density at 600 nm
Q.101 Which component is used to control the pH of a bioreactor?
pH controller with acid/base addition
Temperature controller
Light controller
Pressure controller
Explanation - A pH controller automatically adds acid or base to maintain target pH.
Correct answer is: pH controller with acid/base addition
Q.102 What is the main purpose of a gas inlet in a bioreactor?
Introduce gases like O₂ or CO₂ for cell metabolism
Heat the culture
Add nutrients
Measure temperature
Explanation - Aeration gases supply essential gases for cell respiration and growth.
Correct answer is: Introduce gases like O₂ or CO₂ for cell metabolism
Q.103 Which of the following is a typical sensor used to measure dissolved oxygen?
Oxygen probe
pH probe
Temperature probe
Pressure sensor
Explanation - Oxygen probes provide real-time measurements of dissolved oxygen.
Correct answer is: Oxygen probe
Q.104 Which of the following describes the function of the agitator motor?
To rotate the impeller for mixing
To sterilize the vessel
To measure temperature
To add nutrients
Explanation - The motor drives the impeller to create circulation in the bioreactor.
Correct answer is: To rotate the impeller for mixing
Q.105 What is a typical target dissolved oxygen level for aerobic cell cultures?
5-10%
10-20%
20-30%
30-40%
Explanation - Aerobic cultures usually aim for 5-10% dissolved oxygen to sustain growth.
Correct answer is: 5-10%
Q.106 Which parameter is usually monitored to prevent contamination in a bioreactor?
Temperature
pH
Sterilization status
Lighting
Explanation - Ensuring sterilization eliminates unwanted microbes that could contaminate the culture.
Correct answer is: Sterilization status
Q.107 What is the main function of the baffle in a stirred-tank bioreactor?
Reduce vortex formation and improve mixing
Add nutrients
Cool the medium
Increase temperature
Explanation - Baffles disrupt swirling and promote turbulence, enhancing mixing.
Correct answer is: Reduce vortex formation and improve mixing
Q.108 Which of the following is a common bioprocess product?
Vaccine
Concrete
Solar panels
Batteries
Explanation - Bioreactors are used to produce vaccines and other biopharmaceuticals.
Correct answer is: Vaccine
Q.109 What does a PID controller adjust in a bioreactor?
Aeration and agitation based on sensor feedback
Temperature only
Pressure only
Lighting only
Explanation - PID controllers use error signals to adjust process variables like aeration.
Correct answer is: Aeration and agitation based on sensor feedback
Q.110 Which component provides heat for sterilization in a bioreactor?
Steam jacket
Cooling coils
Light source
Pressure sensor
Explanation - The steam jacket circulates hot steam for sterilization purposes.
Correct answer is: Steam jacket
Q.111 Which of the following is not a typical operating parameter in a bioreactor?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is irrelevant unless the culture is phototrophic.
Correct answer is: Light intensity
Q.112 What is a key advantage of a wave bioreactor?
Gentle mixing suitable for shear-sensitive cells
High shear environment
No gas exchange
Large scale only
Explanation - Wave bioreactors provide gentle mixing, ideal for mammalian cell culture.
Correct answer is: Gentle mixing suitable for shear-sensitive cells
Q.113 What is the primary role of a sparger?
Disperse gas bubbles for oxygen transfer
Add nutrients
Cool the medium
Measure pH
Explanation - Spargers introduce gas into the liquid, enhancing oxygen dissolution.
Correct answer is: Disperse gas bubbles for oxygen transfer
Q.114 Which parameter is directly affected by increasing agitation speed?
Oxygen transfer rate
Temperature
Cell size
Pressure gauge reading
Explanation - Higher agitation increases turbulence, improving oxygen transfer.
Correct answer is: Oxygen transfer rate
Q.115 Which of the following best describes a fed-batch process?
Adding nutrients intermittently during the batch operation
Continuous feeding without stopping the batch
No feeding at all
Only initial feeding
Explanation - Fed-batch involves periodic addition of feed to sustain growth.
Correct answer is: Adding nutrients intermittently during the batch operation
Q.116 What is a common method to sterilize a bioreactor?
Steam sterilization
UV light only
Dry heat only
No sterilization needed
Explanation - Steam sterilization provides high temperatures and pressure to kill microbes.
Correct answer is: Steam sterilization
Q.117 Which sensor monitors dissolved oxygen levels?
Oxygen probe
pH probe
Temperature probe
Pressure sensor
Explanation - Oxygen probes measure the amount of dissolved oxygen in the medium.
Correct answer is: Oxygen probe
Q.118 Which component is responsible for mixing in a stirred-tank bioreactor?
Impeller
Baffles
Aeration inlet
Light source
Explanation - The impeller provides mechanical mixing for uniform culture conditions.
Correct answer is: Impeller
Q.119 What is the typical temperature range for mammalian cell culture?
4-10°C
25-30°C
37-40°C
50-55°C
Explanation - Mammalian cells thrive near body temperature, typically between 37°C and 40°C.
Correct answer is: 37-40°C
Q.120 Which of the following is NOT a typical sensor in a bioreactor?
pH probe
Temperature probe
Light meter
Dissolved oxygen sensor
Explanation - Light meters are rarely used unless culturing photosynthetic organisms.
Correct answer is: Light meter
Q.121 Which of the following best describes a perfusion bioreactor?
Continuous removal of culture and addition of fresh medium
Batch operation only
No aeration
Dry fermentation
Explanation - Perfusion maintains a steady state by constantly perfusing the culture.
Correct answer is: Continuous removal of culture and addition of fresh medium
Q.122 What is the primary purpose of a temperature probe?
Measure temperature
Measure pH
Measure dissolved oxygen
Measure pressure
Explanation - Temperature probes provide accurate readings to keep the culture at the desired temperature.
Correct answer is: Measure temperature
Q.123 Which parameter is commonly adjusted to control the pH of a bioreactor?
Addition of acid/base
Temperature changes
Agitation speed
Light intensity
Explanation - Acid or base is added to maintain the desired pH setpoint.
Correct answer is: Addition of acid/base
Q.124 Which of the following is a key advantage of using a wave bioreactor?
Gentle mixing suitable for sensitive cells
High shear
No gas transfer
High cost
Explanation - Wave bioreactors provide low-shear mixing ideal for mammalian cells.
Correct answer is: Gentle mixing suitable for sensitive cells
Q.125 Which component provides heat for sterilization in a bioreactor?
Steam jacket
Cooling coils
Light source
Pressure sensor
Explanation - Steam jackets circulate hot steam to sterilize the vessel.
Correct answer is: Steam jacket
Q.126 Which of the following is a typical operating parameter in a bioreactor?
Temperature
Color
Light intensity
Wind speed
Explanation - Temperature is a critical variable that must be maintained for optimal cell growth.
Correct answer is: Temperature
Q.127 What is the purpose of the agitator motor?
Rotate the impeller for mixing
Sterilize the vessel
Add nutrients
Cool the medium
Explanation - The motor drives the impeller to stir the culture.
Correct answer is: Rotate the impeller for mixing
Q.128 Which of the following sensors measures dissolved oxygen?
Oxygen probe
pH probe
Temperature probe
Pressure sensor
Explanation - Oxygen probes provide real-time data on oxygen levels in the medium.
Correct answer is: Oxygen probe
Q.129 Which of the following best describes the role of the sparger in a bioreactor?
Distribute gas bubbles for oxygen transfer
Add nutrients
Cool the liquid
Measure pressure
Explanation - Spargers improve gas-liquid mass transfer by creating small bubbles.
Correct answer is: Distribute gas bubbles for oxygen transfer
Q.130 Which of the following is a typical product produced in a bioreactor?
Vaccine
Concrete
Solar panels
Battery cells
Explanation - Bioreactors are used to produce biopharmaceuticals such as vaccines.
Correct answer is: Vaccine
Q.131 Which of the following is not a common operating parameter in bioprocesses?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is seldom monitored unless growing photosynthetic cells.
Correct answer is: Light intensity
Q.132 Which component is responsible for mixing in a stirred-tank bioreactor?
Impeller
Baffles
Aeration inlet
Light source
Explanation - The impeller provides mechanical agitation to homogenize the culture.
Correct answer is: Impeller
Q.133 Which of the following is NOT a typical sensor in a bioreactor?
pH probe
Temperature probe
Light meter
Dissolved oxygen sensor
Explanation - Light meters are rarely used unless culturing light-dependent organisms.
Correct answer is: Light meter
Q.134 Which component of a bioreactor is used to measure temperature?
Thermocouple
pH probe
Oxygen sensor
Pressure gauge
Explanation - Thermocouples provide accurate temperature readings for process control.
Correct answer is: Thermocouple
Q.135 What is the typical target dissolved oxygen for most aerobic cell cultures?
5-10%
10-20%
20-30%
30-40%
Explanation - Maintaining 5-10% dissolved oxygen supports aerobic cell metabolism.
Correct answer is: 5-10%
Q.136 Which of the following best describes the purpose of a sparger?
Introduce gas bubbles for oxygen transfer
Add nutrients
Cool the culture
Measure temperature
Explanation - The sparger disperses gas into the liquid, improving oxygen dissolution.
Correct answer is: Introduce gas bubbles for oxygen transfer
Q.137 Which of the following is a common type of bioreactor?
Stirred tank
Wave bioreactor
Airlift
All of the above
Explanation - Stirred tanks, wave bioreactors, and airlift bioreactors are all widely used.
Correct answer is: All of the above
Q.138 Which component is responsible for maintaining temperature in a bioreactor?
Steam jacket
Cooling coils
Light source
Pressure gauge
Explanation - The steam jacket circulates hot steam to keep the vessel at the desired temperature.
Correct answer is: Steam jacket
Q.139 Which of the following best describes a perfusion bioreactor?
Continuous removal of culture and addition of fresh medium
Batch operation only
No aeration
Dry fermentation
Explanation - Perfusion bioreactors maintain a steady state by continuously perfusing the culture.
Correct answer is: Continuous removal of culture and addition of fresh medium
Q.140 Which parameter is directly affected by increasing agitation speed?
Dissolved oxygen transfer
Temperature
pH
Cell size
Explanation - Higher agitation increases turbulence, which enhances oxygen dissolution.
Correct answer is: Dissolved oxygen transfer
Q.141 What is the main purpose of a baffle in a stirred-tank bioreactor?
Reduce vortex formation and improve mixing
Add nutrients
Cool the culture
Increase temperature
Explanation - Baffles break up swirling motion, creating more uniform mixing.
Correct answer is: Reduce vortex formation and improve mixing
Q.142 Which of the following is not a typical sensor in a bioreactor?
pH probe
Temperature probe
Light meter
Dissolved oxygen sensor
Explanation - Light meters are not generally needed unless culturing phototrophic organisms.
Correct answer is: Light meter
Q.143 What is the primary function of the agitator motor?
Rotate the impeller for mixing
Sterilize the vessel
Add nutrients
Cool the medium
Explanation - The motor drives the impeller to stir the culture uniformly.
Correct answer is: Rotate the impeller for mixing
Q.144 Which of the following is a common method to sterilize a bioreactor?
Steam sterilization
UV only
Dry heat only
No sterilization needed
Explanation - Steam sterilization provides high temperatures and pressure to eliminate microbes.
Correct answer is: Steam sterilization
Q.145 Which of the following describes the function of a sparger in a bioreactor?
Introduce gas bubbles for oxygen transfer
Add nutrients
Cool the culture
Measure temperature
Explanation - Spargers disperse gas into the liquid, improving gas-liquid mass transfer.
Correct answer is: Introduce gas bubbles for oxygen transfer
Q.146 Which parameter is typically monitored to maintain optimal cell growth?
Temperature
pH
Dissolved oxygen
All of the above
Explanation - All three parameters are crucial for maintaining healthy cell culture.
Correct answer is: All of the above
Q.147 Which of the following is NOT a typical component of a stirred-tank bioreactor?
Impeller
Baffles
Light source
Aeration inlet
Explanation - Stirred tanks rarely use light unless culturing light-dependent organisms.
Correct answer is: Light source
Q.148 Which of the following best describes a perfusion bioreactor?
Continuous removal of culture and addition of fresh medium
Batch operation only
No aeration
Dry fermentation
Explanation - Perfusion bioreactors maintain a steady state by continuously perfusing the culture.
Correct answer is: Continuous removal of culture and addition of fresh medium
Q.149 Which parameter is directly affected by increasing agitation speed?
Dissolved oxygen transfer
Temperature
pH
Cell size
Explanation - Higher agitation improves mixing and oxygen transfer.
Correct answer is: Dissolved oxygen transfer
Q.150 Which of the following best describes a wave bioreactor?
Uses rocking motion for gentle mixing
Uses high-speed stirring
No gas transfer
Large scale only
Explanation - Wave bioreactors rock to create fluid movement, suitable for shear-sensitive cells.
Correct answer is: Uses rocking motion for gentle mixing
Q.151 Which component is responsible for maintaining temperature in a bioreactor?
Steam jacket
Cooling coils
Light source
Pressure gauge
Explanation - The steam jacket circulates hot steam to control temperature.
Correct answer is: Steam jacket
Q.152 Which of the following is a common type of bioreactor?
Stirred tank
Wave bioreactor
Airlift
All of the above
Explanation - These are all widely used bioreactor designs.
Correct answer is: All of the above
Q.153 Which of the following is a key advantage of using a wave bioreactor?
Gentle mixing for shear-sensitive cells
High shear environment
No gas transfer
High cost
Explanation - Wave bioreactors provide low-shear environments ideal for mammalian cells.
Correct answer is: Gentle mixing for shear-sensitive cells
Q.154 Which of the following is NOT a typical operating parameter in a bioreactor?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is irrelevant unless the culture is phototrophic.
Correct answer is: Light intensity
Q.155 Which sensor measures temperature in a bioreactor?
Thermocouple
pH probe
Oxygen sensor
Pressure sensor
Explanation - Thermocouples give accurate temperature readings for process control.
Correct answer is: Thermocouple
Q.156 Which parameter is directly affected by increasing agitation speed?
Dissolved oxygen transfer
Temperature
pH
Cell size
Explanation - Higher agitation enhances mixing and oxygen transfer.
Correct answer is: Dissolved oxygen transfer
Q.157 Which component is responsible for mixing in a stirred-tank bioreactor?
Impeller
Baffles
Aeration inlet
Light source
Explanation - The impeller provides mechanical mixing for uniform culture conditions.
Correct answer is: Impeller
Q.158 Which of the following is NOT a typical sensor in a bioreactor?
pH probe
Temperature probe
Light meter
Dissolved oxygen sensor
Explanation - Light meters are rarely used unless culturing light-dependent organisms.
Correct answer is: Light meter
Q.159 What is the main purpose of a bioreactor?
To cultivate living cells for product generation
To produce electricity
To store water
To cool electronics
Explanation - Bioreactors provide controlled environments for biological production.
Correct answer is: To cultivate living cells for product generation
Q.160 Which of the following is a typical output of a bioreactor process?
Insulin
Concrete
Solar panels
Batteries
Explanation - Bioreactors can produce biopharmaceuticals like insulin.
Correct answer is: Insulin
Q.161 Which component of a bioreactor is used to measure dissolved oxygen?
Oxygen sensor
pH sensor
Thermocouple
Pressure gauge
Explanation - Oxygen sensors measure dissolved oxygen levels critical for cell growth.
Correct answer is: Oxygen sensor
Q.162 Which of the following is NOT a common operating parameter in a bioreactor?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is not typically monitored unless cells are photosynthetic.
Correct answer is: Light intensity
Q.163 What is the primary role of the agitator motor?
Rotate the impeller for mixing
Sterilize the vessel
Add nutrients
Cool the medium
Explanation - The motor drives the impeller to provide uniform mixing.
Correct answer is: Rotate the impeller for mixing
Q.164 Which of the following best describes a perfusion bioreactor?
Continuous removal of culture and addition of fresh medium
Batch operation only
No aeration
Dry fermentation
Explanation - Perfusion maintains a steady state by continuously perfusing the culture.
Correct answer is: Continuous removal of culture and addition of fresh medium
Q.165 Which parameter is directly affected by increasing agitation speed?
Dissolved oxygen transfer
Temperature
pH
Cell size
Explanation - Higher agitation increases turbulence, improving oxygen transfer.
Correct answer is: Dissolved oxygen transfer
Q.166 Which of the following is a typical sensor used in a bioreactor?
pH probe
Temperature probe
All of the above
Dissolved oxygen sensor
Explanation - All these sensors are commonly used to monitor bioreactor conditions.
Correct answer is: All of the above
Q.167 What is the main function of the impeller in a stirred-tank bioreactor?
Mix the culture uniformly
Measure temperature
Add nutrients
Measure pressure
Explanation - The impeller agitates the liquid to ensure uniform distribution of cells and nutrients.
Correct answer is: Mix the culture uniformly
Q.168 Which of the following is NOT a typical component of a bioreactor vessel?
Stainless steel
Glass
PVC
Concrete
Explanation - Bioreactor vessels are typically made of stainless steel, glass, or PVC, not concrete.
Correct answer is: Concrete
Q.169 Which of the following is a typical use for a bioreactor?
Production of vaccines
Concrete manufacturing
Solar panel fabrication
Battery recycling
Explanation - Bioreactors are used in biopharmaceutical production such as vaccines.
Correct answer is: Production of vaccines
Q.170 What is the purpose of a temperature probe?
Measure temperature
Measure pH
Measure dissolved oxygen
Measure pressure
Explanation - Temperature probes provide accurate readings of the culture temperature.
Correct answer is: Measure temperature
Q.171 Which of the following is a typical sensor in a bioreactor?
pH probe
Temperature probe
All of the above
Dissolved oxygen sensor
Explanation - All these sensors are commonly used for monitoring bioreactor conditions.
Correct answer is: All of the above
Q.172 What is the main purpose of the baffles in a stirred-tank bioreactor?
Prevent vortex formation and improve mixing
Add nutrients
Cool the medium
Increase temperature
Explanation - Baffles improve turbulence and mixing by disrupting swirling motion.
Correct answer is: Prevent vortex formation and improve mixing
Q.173 Which of the following best describes a wave bioreactor?
Uses rocking motion for gentle mixing
Uses high-speed stirring
No gas transfer
Large scale only
Explanation - Wave bioreactors rock to create fluid movement suitable for shear-sensitive cells.
Correct answer is: Uses rocking motion for gentle mixing
Q.174 What is the primary role of the steam jacket in a bioreactor?
Sterilize the vessel
Cool the medium
Add nutrients
Measure temperature
Explanation - The steam jacket circulates hot steam for sterilization and temperature control.
Correct answer is: Sterilize the vessel
Q.175 Which of the following is NOT a typical operating parameter in bioprocessing?
Temperature
pH
Light intensity
Dissolved oxygen
Explanation - Light is not normally monitored unless the culture is photosynthetic.
Correct answer is: Light intensity
Q.176 Which component of a bioreactor is used to measure temperature?
Thermocouple
pH probe
Oxygen sensor
Pressure gauge
Explanation - Thermocouples provide accurate temperature readings for process control.
Correct answer is: Thermocouple
Q.177 What is the main advantage of using a perfusion bioreactor?
Continuous removal and addition of medium for high cell density
Batch operation only
No aeration
Dry fermentation
Explanation - Perfusion supports sustained high cell densities and product yield.
Correct answer is: Continuous removal and addition of medium for high cell density
Q.178 Which of the following is a typical type of bioreactor?
Stirred tank
Wave bioreactor
Airlift
All of the above
Explanation - These are all common bioreactor designs used in industry.
Correct answer is: All of the above
Q.179 What is the main purpose of a sparger in a bioreactor?
Introduce gas bubbles for oxygen transfer
Add nutrients
Cool the medium
Measure temperature
Explanation - The sparger disperses gas, improving oxygen dissolution into the culture.
Correct answer is: Introduce gas bubbles for oxygen transfer
Q.180 Which sensor measures dissolved oxygen levels in a bioreactor?
Oxygen sensor
pH probe
Temperature probe
Pressure sensor
Explanation - Oxygen sensors provide real-time monitoring of dissolved oxygen.
Correct answer is: Oxygen sensor
Q.181 Which component is responsible for stirring in a bioreactor?
Impeller
Baffles
Aeration inlet
Light source
Explanation - The impeller provides mechanical agitation for uniform mixing.
Correct answer is: Impeller