Q.1 Which electrical component is commonly used to maintain a constant temperature in a fermentation bioreactor?
Capacitive load
Thermostatic relay
Inductive choke
Resistive heater
Explanation - Resistive heaters convert electrical energy into heat, making them ideal for controlling the temperature in fermentation tanks.
Correct answer is: Resistive heater
Q.2 What type of sensor is typically used to monitor dissolved oxygen levels in a bioreactor?
Thermocouple
Optical fiber sensor
Clark-type electrode
Capacitance probe
Explanation - Clark-type oxygen electrodes use a membrane selective to oxygen, providing accurate dissolved oxygen readings essential for fermentation control.
Correct answer is: Clark-type electrode
Q.3 In a bioprocess control system, which protocol is most commonly used for communication between PLCs and SCADA?
Modbus RTU
USB
Bluetooth LE
HDMI
Explanation - Modbus RTU is a serial communication protocol widely adopted in industrial automation for linking PLCs and SCADA systems.
Correct answer is: Modbus RTU
Q.4 Which of the following is NOT an electrical safety concern in a fermentation facility?
Grounding of equipment
Water ingress into circuits
Proper labeling of voltage levels
Use of magnetic stirrers
Explanation - Magnetic stirrers themselves pose no electrical hazard; the other options directly affect electrical safety.
Correct answer is: Use of magnetic stirrers
Q.5 What is the primary function of a PID controller in a fermentation process?
Measure pH
Regulate agitation speed
Adjust feed rate
Stabilize temperature
Explanation - A PID controller uses error signals to adjust heating/cooling elements, maintaining the desired temperature during fermentation.
Correct answer is: Stabilize temperature
Q.6 Which power supply type is preferred for high-speed data acquisition in bioprocess monitoring?
AC line voltage
Uninterruptible Power Supply (UPS)
Battery backup
DC wall adapter
Explanation - UPS systems provide clean, uninterrupted DC power essential for reliable data acquisition in critical fermentation monitoring.
Correct answer is: Uninterruptible Power Supply (UPS)
Q.7 The use of which type of valve is common for controlling gas flow into a bioreactor?
Ball valve
Butterfly valve
Globe valve
Needle valve
Explanation - Globe valves allow fine control of gas flow, which is critical for maintaining proper dissolved oxygen and CO2 levels.
Correct answer is: Globe valve
Q.8 What does the acronym “SP” stand for in a fermentation control context?
Standard Parameter
Set Point
Sampling Point
Signal Path
Explanation - SP refers to the desired set point value that the controller attempts to maintain, such as temperature or pH.
Correct answer is: Set Point
Q.9 Which of the following is a key advantage of using a 4–20 mA loop in fermentation instrumentation?
Higher bandwidth
Lower power consumption
Robust against noise
Requires no calibration
Explanation - The 4–20 mA signal is resistant to electrical noise and allows for accurate analog transmission over long distances.
Correct answer is: Robust against noise
Q.10 Which electrical parameter is most critical for designing the agitation system of a 10‑L bioreactor?
Voltage rating
Power rating
Frequency
Insulation class
Explanation - The motor’s power rating determines its ability to provide sufficient torque and mixing speed for a given reactor volume.
Correct answer is: Power rating
Q.11 What role does a PID loop play when adjusting the feed of nutrients in a fed‑batch fermentation?
Maintains constant pH
Keeps feed valve open
Regulates nutrient concentration
Controls agitation speed
Explanation - The PID controller can modulate the feed pump to keep the concentration of nutrients at the desired set point.
Correct answer is: Regulates nutrient concentration
Q.12 Which type of relay is commonly used to switch high‑current pumps in a bioprocess?
Solid‑state relay
Thermal overload relay
Mechanical relay
Micro‑switch
Explanation - Mechanical relays can handle the high inrush currents and continuous load of bioprocess pumps.
Correct answer is: Mechanical relay
Q.13 Which electrical safety standard is relevant for instrumentation in a wet fermentation environment?
IEC 60204-1
IEC 60529
IEC 61000-4-4
IEC 61508
Explanation - IEC 60529 defines the IP (Ingress Protection) rating, which indicates the protection level against water and dust for electrical equipment.
Correct answer is: IEC 60529
Q.14 Why are Hall‑effect sensors preferred over mechanical switches for measuring stirring speed?
They are cheaper
They require no calibration
They have no moving parts
They can be mounted underwater
Explanation - Hall‑effect sensors measure magnetic fields without physical contact, reducing wear and the need for maintenance.
Correct answer is: They have no moving parts
Q.15 Which electrical component is used to isolate a bioprocess control circuit from the main supply for safety?
Fuse
Isolation transformer
Resistor
Diode array
Explanation - Isolation transformers provide galvanic isolation, preventing hazardous voltages from reaching the control system.
Correct answer is: Isolation transformer
Q.16 What is the purpose of a back‑flush valve in a bioreactor?
Regulate gas flow
Remove dead‑volume liquid
Adjust agitation speed
Control temperature
Explanation - The back‑flush valve is used to empty the dead‑volume of the reactor, ensuring accurate volume measurements.
Correct answer is: Remove dead‑volume liquid
Q.17 Which type of power supply is recommended for high‑voltage sterilizers used in bioprocessing?
Linear regulated supply
Switch‑mode supply
Battery supply
Transformer‑less supply
Explanation - Switch‑mode supplies offer high efficiency and can handle the high voltage and current needed for sterilization units.
Correct answer is: Switch‑mode supply
Q.18 Why is grounding critical in a fermentation laboratory?
To reduce electromagnetic interference
To keep the floor dry
To provide a reference for potential
To improve ventilation
Explanation - Grounding establishes a safe reference voltage, preventing electrical shock and ensuring accurate sensor readings.
Correct answer is: To provide a reference for potential
Q.19 What is the main reason for using a 3‑phase supply in a large bioreactor?
To reduce voltage drop
To allow higher torque motors
To increase resistance
To simplify wiring
Explanation - Three‑phase motors provide higher starting torque and smoother operation, essential for large‑scale agitation.
Correct answer is: To allow higher torque motors
Q.20 Which sensor type would you use to detect CO₂ levels in a bioreactor?
Electrochemical sensor
pH electrode
Temperature probe
Humidity sensor
Explanation - Electrochemical CO₂ sensors measure the concentration of CO₂ gas, helping regulate the dissolved CO₂ in fermentation.
Correct answer is: Electrochemical sensor
Q.21 A 5‑V, 1‑mA reference voltage is used in a bioprocess control loop. Which component ensures stability?
Zener diode
Voltage regulator
Resistor network
Capacitor
Explanation - A voltage regulator maintains a steady output voltage regardless of load variations, critical for sensitive instrumentation.
Correct answer is: Voltage regulator
Q.22 Which of the following is a key design consideration for the power cable of a bioreactor stirrer?
Cable length
Cable color
Cable flexibility
Cable rating (kVA)
Explanation - The cable must support the motor’s kVA rating to prevent overheating and voltage drop during operation.
Correct answer is: Cable rating (kVA)
Q.23 The use of which of these techniques improves the accuracy of pH measurement in a bioreactor?
Automatic calibration routine
Manual adjustment only
Temperature compensation
High‑frequency noise filtering
Explanation - Automatic calibration ensures that pH probes remain accurate over time, compensating for drift and electrode aging.
Correct answer is: Automatic calibration routine
Q.24 What is the purpose of a limit switch on a bioreactor fill line?
To stop the pump when full
To measure temperature
To monitor pressure
To regulate agitation speed
Explanation - Limit switches provide a mechanical cutoff to prevent over‑filling and potential spills.
Correct answer is: To stop the pump when full
Q.25 In a fermentation process, which electrical parameter is directly controlled to maintain pH?
Voltage to a pH probe
Current through a titrant pump
Power to the heater
Frequency of the stirrer motor
Explanation - The controller adjusts the pump current to add acid or base, thereby controlling the pH.
Correct answer is: Current through a titrant pump
Q.26 Which type of cable is best suited for interconnecting sensors in a humid fermentation environment?
Standard copper wire
Water‑proof shielded cable
Plastic insulated wire
Fiber‑optic cable
Explanation - Water‑proof shielding prevents moisture ingress and electromagnetic interference, protecting sensor signals.
Correct answer is: Water‑proof shielded cable
Q.27 What is a primary benefit of using a variable frequency drive (VFD) on a bioreactor motor?
Reduced noise
Precise speed control
Increased power consumption
Simpler wiring
Explanation - A VFD allows the operator to adjust motor speed precisely, optimizing mixing and oxygen transfer.
Correct answer is: Precise speed control
Q.28 Which of the following best describes a 'PID' controller?
Proportional, Integral, Derivative
Power, Insulation, Density
Pulse, Inertia, Delay
Phase, Impedance, Dynamic
Explanation - PID stands for Proportional–Integral–Derivative, the three components of a classic feedback control algorithm.
Correct answer is: Proportional, Integral, Derivative
Q.29 A 24‑V DC motor is used to stir a bioreactor. What is the most suitable type of switch to control it?
DPDT toggle switch
SPST toggle switch
DPDT rotary switch
Three‑way switch
Explanation - A DPDT switch allows reversing the motor direction or connecting/disconnecting the motor in a safe way.
Correct answer is: DPDT toggle switch
Q.30 What is the main electrical consideration when designing an automated sampling system?
Number of ports
Signal amplification
Power supply isolation
Ventilation
Explanation - Isolation prevents hazardous voltages from reaching the sampling mechanism and protects against contamination.
Correct answer is: Power supply isolation
Q.31 Which component is used to filter electrical noise from a 4–20 mA signal line?
Capacitor
Inductor
Ferrite bead
Transformer
Explanation - Ferrite beads suppress high‑frequency noise, ensuring signal integrity over long distances.
Correct answer is: Ferrite bead
Q.32 The term 'dead‑volume' in a bioreactor refers to:
The unused headspace
The volume that cannot be stirred
The volume of the liquid not affected by mixing
The volume that must be discarded
Explanation - Dead‑volume is the portion of the reactor where mixing is ineffective, affecting process uniformity.
Correct answer is: The volume of the liquid not affected by mixing
Q.33 What is the primary purpose of a 'bleed valve' in a bioreactor gas line?
To release excess pressure
To add oxygen
To measure temperature
To control agitation
Explanation - A bleed valve allows controlled venting of gas to maintain safe pressure levels inside the reactor.
Correct answer is: To release excess pressure
Q.34 Which type of sensor provides a digital output for temperature measurement in a bioprocess?
Thermocouple
RTD with ADC
Thermistor
Infrared thermometer
Explanation - An RTD (Resistance Temperature Detector) combined with an ADC converts resistance to a digital signal.
Correct answer is: RTD with ADC
Q.35 What is the advantage of using a 2‑wire sensor configuration in bioprocess monitoring?
Simpler wiring
Higher accuracy
Reduced noise
No need for power supply
Explanation - 2‑wire sensors reduce cabling complexity but may suffer from lead resistance errors.
Correct answer is: Simpler wiring
Q.36 In an automated fermentation system, what is the function of a 'PID loop' on the pH controller?
Measure pH
Maintain a constant pH by controlling the addition of acid/base
Record data
Display set point
Explanation - The PID loop adjusts the flow of acid or base to keep the measured pH at the set point.
Correct answer is: Maintain a constant pH by controlling the addition of acid/base
Q.37 Which of the following is a typical feature of a process safety instrument system (PSI) in bioprocessing?
Alarm only
Manual shut‑off valves
Automatic shutdown on parameter violation
Single‑point monitoring
Explanation - PSI systems automatically act to protect equipment and personnel when process parameters exceed limits.
Correct answer is: Automatic shutdown on parameter violation
Q.38 Which of the following best describes 'process analytical technology' (PAT) in bioprocessing?
Post‑process analysis
Real‑time monitoring of critical quality attributes
Statistical quality control
Manual sampling
Explanation - PAT enables real‑time data acquisition and decision making, improving product quality and process efficiency.
Correct answer is: Real‑time monitoring of critical quality attributes
Q.39 What does 'IP65' signify for an electrical device used in a fermentation lab?
Operable at 65°C
Protected against water splashes
Dust tight, protected against water jets
Insulated to 6500 V
Explanation - IP65 rating indicates dust‑tight protection and resistance to water jets, suitable for wet environments.
Correct answer is: Dust tight, protected against water jets
Q.40 Which element of the control loop is responsible for correcting steady‑state error over time?
Proportional term
Derivative term
Integral term
Reset term
Explanation - The integral action accumulates error over time, eliminating residual steady‑state error.
Correct answer is: Integral term
Q.41 Which type of sensor is preferred for measuring turbidity in a bioreactor?
Optical sensor
pH electrode
Temperature probe
Pressure transducer
Explanation - Optical sensors detect light scattering, providing a reliable turbidity measurement.
Correct answer is: Optical sensor
Q.42 What is the function of a 'bleed port' in a pressure‑controlled bioreactor?
Vent excess gas
Measure pressure
Control temperature
Add nutrients
Explanation - Bleed ports allow safe release of gas to maintain desired pressure and avoid over‑pressurization.
Correct answer is: Vent excess gas
Q.43 Which electrical device ensures that a pump only starts when its motor is properly connected?
Inrush current limiter
Relay
Check valve
Pressure sensor
Explanation - A check valve prevents back‑flow, ensuring the pump runs only when the system is primed.
Correct answer is: Check valve
Q.44 What is the main purpose of a 'thermostat' in a fermentation process?
To adjust agitation speed
To maintain a fixed temperature
To measure pH
To control pressure
Explanation - A thermostat controls heating or cooling elements, keeping the reactor at the desired temperature.
Correct answer is: To maintain a fixed temperature
Q.45 Why is a 'solid‑state relay' (SSR) preferred for controlling a heater in a bioreactor?
It is cheaper
It has no mechanical wear
It can handle high temperatures
It requires no external power
Explanation - SSR's lack of moving parts allows reliable operation in high‑temperature or high‑frequency switching scenarios.
Correct answer is: It has no mechanical wear
Q.46 Which of these is a typical parameter measured by a 'pH probe' in fermentation?
Electrical conductivity
Volatile acidity
pH value
Oxygen concentration
Explanation - pH probes directly measure the acidity or alkalinity of the fermentation broth.
Correct answer is: pH value
Q.47 The 'set‑point' (SP) for dissolved oxygen is usually expressed in terms of:
Parts per million (ppm)
Percentage saturation
Voltage
Temperature
Explanation - Dissolved oxygen set points are commonly expressed as a percentage of the saturation concentration at a given temperature.
Correct answer is: Percentage saturation
Q.48 Which type of transformer is used to step down a 220‑V AC supply to 24‑V DC for a bioprocess controller?
Isolation transformer
Power transformer
Audio transformer
Signal transformer
Explanation - An isolation transformer provides both voltage step‑down and safety isolation for the control circuitry.
Correct answer is: Isolation transformer
Q.49 What is the purpose of a 'proportional band' in a PID controller?
To define the range of error for proportional action
To set the maximum output
To limit the integral term
To adjust the derivative response
Explanation - The proportional band determines how much the controller output changes in response to error within a specified range.
Correct answer is: To define the range of error for proportional action
Q.50 Which safety feature is essential for electrical equipment in a bioreactor that has high humidity?
Waterproof enclosure
High‑voltage rating
Low resistance path
Fast‑acting fuse
Explanation - A waterproof enclosure protects the internals from moisture, preventing corrosion and electrical shorts.
Correct answer is: Waterproof enclosure
Q.51 What does the acronym 'HMI' stand for in a bioprocess control system?
High‑Speed Monitor Interface
Human‑Machine Interface
Hardware Maintenance Indicator
Hydraulic Monitoring Instrument
Explanation - HMI is the interface that allows operators to monitor and control process parameters via a graphical display.
Correct answer is: Human‑Machine Interface
Q.52 Which component is used to convert a high‑frequency AC signal to a low‑frequency DC signal for sensor output?
Rectifier
Inverter
Filter
Oscillator
Explanation - A rectifier converts AC to DC, enabling stable sensor signal transmission.
Correct answer is: Rectifier
Q.53 In a fed‑batch fermentation, what is the primary purpose of a 'titration loop'?
To control agitation speed
To add nutrients gradually
To measure pH
To control temperature
Explanation - The titration loop ensures that nutrients are added in a controlled manner, preventing nutrient shock.
Correct answer is: To add nutrients gradually
Q.54 Which electrical safety device is critical when wiring a bioprocess controller to the mains?
Thermal cut‑off
Ground fault circuit interrupter (GFCI)
Fuse
Pressure relief valve
Explanation - GFCI monitors current imbalance, protecting against electric shock in moist environments.
Correct answer is: Ground fault circuit interrupter (GFCI)
Q.55 What is the main advantage of using an 'optical fiber sensor' for monitoring pH?
High temperature tolerance
No electrical interference
Low cost
Simple calibration
Explanation - Optical fiber sensors are immune to electromagnetic interference, providing accurate readings in noisy industrial settings.
Correct answer is: No electrical interference
Q.56 Which of the following is a typical method for cleaning a bioreactor without disassembly?
Sterile filtration
Cavitation cleaning
Ultrasonic cleaning
Chemical soaking
Explanation - Ultrasonic waves can remove bio‑films and residues from surfaces while the reactor remains in place.
Correct answer is: Ultrasonic cleaning
Q.57 Which parameter is usually monitored to prevent over‑oxygenation in a fermentation?
Temperature
pH
Dissolved oxygen (DO)
Pressure
Explanation - High DO can cause oxidative stress; sensors monitor DO to keep it within optimal ranges.
Correct answer is: Dissolved oxygen (DO)
Q.58 What does the 'critical quality attribute' (CQA) refer to in pharmaceutical biotechnology?
A property that determines product safety
The color of the product
The batch number
The expiration date
Explanation - CQAs are measurable properties that must be controlled to ensure product quality and safety.
Correct answer is: A property that determines product safety
Q.59 Which of these is a common failure mode for a pH electrode in a bioprocess?
Overheating
Electrode drift
Mechanical breakage
Signal overload
Explanation - Electrode drift refers to gradual changes in sensor response, requiring regular calibration.
Correct answer is: Electrode drift
Q.60 What type of filter is most appropriate for protecting a 4–20 mA sensor line from electrical noise?
Low‑pass filter
High‑pass filter
Band‑stop filter
Band‑pass filter
Explanation - A low‑pass filter allows low‑frequency signals to pass while attenuating high‑frequency noise.
Correct answer is: Low‑pass filter
Q.61 Which component of a bioreactor is used to maintain the appropriate shear environment for sensitive cells?
Stir bar
Agitator shaft
Propeller
Paddle
Explanation - Stir bars create controlled shear forces suitable for delicate cell cultures.
Correct answer is: Stir bar
Q.62 What is the function of a 'pressure‑sensing differential gauge' in a fermentation system?
Measure temperature
Control agitation speed
Detect pressure differences
Regulate pH
Explanation - Differential gauges measure the pressure difference between two points, aiding in monitoring gas-liquid balance.
Correct answer is: Detect pressure differences
Q.63 Which electrical measurement is essential for determining the power factor of a bioreactor motor?
Voltage and current phasors
Temperature and speed
Frequency and duty cycle
Resistance and inductance
Explanation - Power factor is calculated from the phase relationship between voltage and current phasors.
Correct answer is: Voltage and current phasors
Q.64 Which of the following is NOT a typical requirement for an electrode used in a bioprocess?
Chemical compatibility
Electrical insulation
Mechanical strength
High temperature tolerance
Explanation - Electrodes must be electrically active; insulation would prevent them from functioning.
Correct answer is: Electrical insulation
Q.65 What type of current is generated by a 'thermocouple' for temperature measurement?
Alternating current
Direct current
Pulse current
Neutral current
Explanation - Thermocouples generate a small DC voltage proportional to temperature difference.
Correct answer is: Direct current
Q.66 Which component provides a safety function in case of an over‑temperature condition in a bioreactor?
Pressure relief valve
Thermal cut‑off
Inrush current limiter
Pressure gauge
Explanation - A thermal cut‑off shuts off power when the temperature exceeds a set limit, preventing overheating.
Correct answer is: Thermal cut‑off
Q.67 The 'set‑point' (SP) of a bioreactor pH controller is usually adjusted by:
Changing the reference voltage
Repositioning the pH electrode
Programming the controller
Altering the gas flow
Explanation - The set point is defined within the controller’s software or firmware.
Correct answer is: Programming the controller
Q.68 Which device converts AC to DC for use in bioprocess electronics?
Transformers
Rectifiers
Inverters
Oscillators
Explanation - Rectifiers are used to supply DC power to control circuits from an AC mains supply.
Correct answer is: Rectifiers
Q.69 What is the primary benefit of using a 'balanced pair' of wires for sensor signals?
Improved speed
Reduced crosstalk
Simplified wiring
Increased voltage drop
Explanation - Balanced wiring cancels common‑mode noise, improving signal integrity.
Correct answer is: Reduced crosstalk
Q.70 Which of the following is a key advantage of using a digital temperature probe in a fermentation process?
Low cost
High accuracy
No calibration needed
Easy to replace
Explanation - Digital probes provide precise, stable temperature readings crucial for process control.
Correct answer is: High accuracy
Q.71 In a bioprocess, a 'feedback loop' primarily controls which parameter?
Time
Parameter being monitored (e.g., temperature)
Electrical supply voltage
Ambient light
Explanation - A feedback loop uses real‑time measurements to adjust the system and maintain the desired parameter.
Correct answer is: Parameter being monitored (e.g., temperature)
Q.72 Which type of sensor is used to measure the level of liquid in a fermenter?
Temperature probe
Level sensor
pH electrode
Pressure transducer
Explanation - Level sensors detect the liquid height, enabling volume control and monitoring.
Correct answer is: Level sensor
Q.73 What is the purpose of a 'safety interlock' in a bioreactor control system?
To enable faster stirring
To prevent operation under unsafe conditions
To reduce power consumption
To increase temperature set points
Explanation - Safety interlocks halt the process if any parameter exceeds safe limits, protecting equipment and personnel.
Correct answer is: To prevent operation under unsafe conditions
Q.74 Which electrical device is commonly used to provide a clean and stable 48‑V DC supply for PLCs?
Transformer
Voltage regulator
Power supply
Resistor divider
Explanation - A regulated power supply ensures a constant DC voltage for reliable PLC operation.
Correct answer is: Power supply
Q.75 The 'critical process parameter' (CPP) in fermentation typically refers to:
pH and temperature
Color of the broth
Batch number
Expiration date
Explanation - CPPs are the parameters that must be tightly controlled to achieve desired product quality.
Correct answer is: pH and temperature
Q.76 What is the main function of a 'differential pressure transmitter' in a bioreactor?
Measure temperature
Measure the pressure difference between two points
Measure flow rate
Control agitation speed
Explanation - It provides a signal proportional to the pressure difference, useful for monitoring gas-liquid interactions.
Correct answer is: Measure the pressure difference between two points
Q.77 Which type of electrical circuit breaker is most suitable for protecting a bioprocess pump?
Miniature circuit breaker
Ground fault circuit breaker
Fuse
Thermal‑magnetic circuit breaker
Explanation - It protects against overloads and short circuits, ensuring safe operation of the pump.
Correct answer is: Thermal‑magnetic circuit breaker
Q.78 What is the primary advantage of using 'phase‑locked loop' (PLL) in a bioprocess instrumentation system?
Simplify wiring
Improve signal timing
Reduce power consumption
Lower cost
Explanation - PLL synchronizes signals, reducing jitter and enhancing measurement accuracy.
Correct answer is: Improve signal timing
Q.79 Which parameter is typically monitored to detect foam build‑up in a fermentation?
pH
Dissolved oxygen
Foam sensor
Temperature
Explanation - Foam sensors detect excessive foam, triggering defoaming actions.
Correct answer is: Foam sensor
Q.80 What is the role of an 'auto‑cleaning cycle' (ACC) in a bioreactor?
Automate stirring
Sterilize the vessel without disassembly
Add nutrients automatically
Control temperature
Explanation - ACC uses steam and cleaning agents to disinfect the reactor between batches.
Correct answer is: Sterilize the vessel without disassembly
Q.81 Which type of sensor is best for measuring the conductivity of a fermentation broth?
Optical sensor
Thermocouple
Conductivity probe
Pressure transducer
Explanation - Conductivity probes measure the electrical conductivity, indicating ion concentration.
Correct answer is: Conductivity probe
Q.82 What is the purpose of a 'bleed valve' in a pressure‑controlled bioprocess?
To vent excess gas
To add nutrients
To measure temperature
To control agitation speed
Explanation - Bleed valves release pressure safely, preventing over‑pressurization.
Correct answer is: To vent excess gas
Q.83 Which of the following is a key safety requirement for a bioprocess instrument in a wet environment?
High voltage rating
Low current rating
Waterproof enclosure (IP65+)
High temperature tolerance
Explanation - Waterproof enclosures protect electronics from moisture and accidental splashes.
Correct answer is: Waterproof enclosure (IP65+)
Q.84 The term 'dead‑volume' refers to the portion of a bioreactor that:
Is not stirred
Is not sterilized
Contains excess gas
Is always filled with liquid
Explanation - Dead‑volume is the part of the reactor where mixing is ineffective, affecting uniformity.
Correct answer is: Is not stirred
Q.85 In a fermentation process, which parameter is adjusted by adding acid or base to maintain a specific value?
Temperature
pH
Dissolved oxygen
Pressure
Explanation - Adding acid/base changes the pH, allowing the controller to maintain the set point.
Correct answer is: pH
Q.86 Which of these devices is used to measure the rotation speed of a bioreactor agitator?
Anemometer
Tachometer
Barometer
Calorimeter
Explanation - A tachometer reads the RPM of the agitator, ensuring proper mixing.
Correct answer is: Tachometer
Q.87 The 'process variable' (PV) in a control loop is:
The desired set point
The measured value of a process parameter
The maximum allowed value
The time delay
Explanation - PV is the real‑time measurement that the controller uses to determine error.
Correct answer is: The measured value of a process parameter
Q.88 Which of the following is a common failure mode for a dissolved oxygen probe?
High temperature tolerance
Signal drift
Fast response time
High mechanical strength
Explanation - Dissolved oxygen probes can drift over time, requiring recalibration.
Correct answer is: Signal drift
Q.89 Which component is used to isolate a 24‑V control circuit from a 230‑V mains supply?
Transformer
Rectifier
Fuse
Inductor
Explanation - A transformer steps down the voltage and provides galvanic isolation.
Correct answer is: Transformer
Q.90 What is the main benefit of using a 'balanced pair' of wires for sensor signals?
Simpler wiring
Reduced crosstalk
Higher voltage drop
Lower cost
Explanation - Balanced wiring cancels common‑mode noise, improving signal integrity.
Correct answer is: Reduced crosstalk
Q.91 Which of the following sensors is used to monitor the level of liquid in a fermenter?
Temperature probe
Level sensor
pH electrode
Pressure transducer
Explanation - Level sensors detect the liquid height, enabling volume control and monitoring.
Correct answer is: Level sensor
Q.92 What is the purpose of a 'safety interlock' in a bioreactor control system?
To enable faster stirring
To prevent operation under unsafe conditions
To reduce power consumption
To increase temperature set points
Explanation - Safety interlocks halt the process if any parameter exceeds safe limits, protecting equipment and personnel.
Correct answer is: To prevent operation under unsafe conditions
Q.93 Which device is commonly used to provide a clean and stable 48‑V DC supply for PLCs?
Transformer
Voltage regulator
Power supply
Resistor divider
Explanation - A regulated power supply ensures a constant DC voltage for reliable PLC operation.
Correct answer is: Power supply
Q.94 The 'critical process parameter' (CPP) in fermentation typically refers to:
pH and temperature
Color of the broth
Batch number
Expiration date
Explanation - CPPs are the parameters that must be tightly controlled to achieve desired product quality.
Correct answer is: pH and temperature
Q.95 Which electrical device is most suitable for protecting a bioprocess pump?
Miniature circuit breaker
Ground fault circuit breaker
Fuse
Thermal‑magnetic circuit breaker
Explanation - It protects against overloads and short circuits, ensuring safe operation of the pump.
Correct answer is: Thermal‑magnetic circuit breaker
Q.96 What is the role of an 'auto‑cleaning cycle' (ACC) in a bioreactor?
Automate stirring
Sterilize the vessel without disassembly
Add nutrients automatically
Control temperature
Explanation - ACC uses steam and cleaning agents to disinfect the reactor between batches.
Correct answer is: Sterilize the vessel without disassembly
Q.97 Which of the following is a typical failure mode for a dissolved oxygen probe?
High temperature tolerance
Signal drift
Fast response time
High mechanical strength
Explanation - Dissolved oxygen probes can drift over time, requiring recalibration.
Correct answer is: Signal drift
Q.98 In a bioprocess, what is the main advantage of using a 'digital temperature probe'?
Low cost
High accuracy
No calibration needed
Easy to replace
Explanation - Digital probes provide precise, stable temperature readings crucial for process control.
Correct answer is: High accuracy
Q.99 Which of these is a key advantage of using a 'balanced pair' of wires for sensor signals?
Simplified wiring
Reduced crosstalk
Increased voltage drop
Higher cost
Explanation - Balanced wiring cancels common‑mode noise, improving signal integrity.
Correct answer is: Reduced crosstalk
Q.100 What type of sensor is best for measuring turbidity in a bioreactor?
Optical sensor
pH electrode
Temperature probe
Pressure transducer
Explanation - Optical sensors detect light scattering, providing a reliable turbidity measurement.
Correct answer is: Optical sensor
Q.101 Which type of voltage is used for the main power supply of a 4‑phase bioreactor agitator?
110 VAC
220 VAC
48 VDC
400 VAC
Explanation - Large industrial motors typically run on high‑voltage AC, such as 400 VAC.
Correct answer is: 400 VAC
Q.102 In a fermentation process, which parameter is monitored to prevent over‑oxygenation?
Temperature
pH
Dissolved oxygen (DO)
Pressure
Explanation - High DO can cause oxidative stress; sensors monitor DO to keep it within optimal ranges.
Correct answer is: Dissolved oxygen (DO)
Q.103 What is the function of an 'inrush current limiter' in a bioprocess pump?
Prevent overheating during start‑up
Increase speed
Reduce power consumption
Control pressure
Explanation - It limits the surge current that occurs when a motor starts, protecting the power supply.
Correct answer is: Prevent overheating during start‑up
Q.104 Which electrical component ensures that a bioprocess control circuit operates at a lower voltage than the mains?
Voltage regulator
Transformer
Inductor
Capacitor
Explanation - A transformer steps down the mains voltage and provides isolation.
Correct answer is: Transformer
Q.105 What does the acronym 'HMI' stand for in a bioprocess control system?
High‑Speed Monitor Interface
Human‑Machine Interface
Hardware Maintenance Indicator
Hydraulic Monitoring Instrument
Explanation - HMI is the interface that allows operators to monitor and control process parameters via a graphical display.
Correct answer is: Human‑Machine Interface
Q.106 Which of the following sensors provides a digital output for temperature measurement in a bioprocess?
Thermocouple
RTD with ADC
Thermistor
Infrared thermometer
Explanation - An RTD (Resistance Temperature Detector) combined with an ADC converts resistance to a digital signal.
Correct answer is: RTD with ADC
Q.107 The 'set‑point' (SP) of a bioreactor pH controller is usually adjusted by:
Changing the reference voltage
Repositioning the pH electrode
Programming the controller
Altering the gas flow
Explanation - The set point is defined within the controller’s software or firmware.
Correct answer is: Programming the controller
Q.108 Which of the following is a typical failure mode for a pH electrode in a bioprocess?
Overheating
Electrode drift
Mechanical breakage
Signal overload
Explanation - Electrode drift refers to gradual changes in sensor response, requiring regular calibration.
Correct answer is: Electrode drift
Q.109 What is the purpose of a 'bleed port' in a pressure‑controlled bioprocess?
Vent excess gas
Measure pressure
Control temperature
Add nutrients
Explanation - Bleed ports allow safe release of pressure, preventing over‑pressurization.
Correct answer is: Vent excess gas
Q.110 Which of these components is most commonly used to isolate a bioprocess control circuit from the mains?
Transformer
Capacitor
Inductor
Resistor
Explanation - A transformer steps down voltage and provides electrical isolation.
Correct answer is: Transformer
Q.111 Which of the following is a key advantage of using a digital temperature probe in a fermentation process?
Low cost
High accuracy
No calibration needed
Easy to replace
Explanation - Digital probes provide precise, stable temperature readings crucial for process control.
Correct answer is: High accuracy
Q.112 What type of sensor is used to measure the level of liquid in a fermenter?
Temperature probe
Level sensor
pH electrode
Pressure transducer
Explanation - Level sensors detect the liquid height, enabling volume control and monitoring.
Correct answer is: Level sensor
Q.113 Which of the following is a typical failure mode for a dissolved oxygen probe?
High temperature tolerance
Signal drift
Fast response time
High mechanical strength
Explanation - Dissolved oxygen probes can drift over time, requiring recalibration.
Correct answer is: Signal drift
Q.114 The 'critical process parameter' (CPP) in fermentation typically refers to:
pH and temperature
Color of the broth
Batch number
Expiration date
Explanation - CPPs are the parameters that must be tightly controlled to achieve desired product quality.
Correct answer is: pH and temperature
Q.115 What is the main advantage of using a 'solid‑state relay' (SSR) for controlling a heater in a bioreactor?
It is cheaper
It has no mechanical wear
It can handle high temperatures
It requires no external power
Explanation - SSR's lack of moving parts allows reliable operation in high‑temperature or high‑frequency switching scenarios.
Correct answer is: It has no mechanical wear
Q.116 Which of the following sensors is best for measuring the conductivity of a fermentation broth?
Optical sensor
Thermocouple
Conductivity probe
Pressure transducer
Explanation - Conductivity probes measure the electrical conductivity, indicating ion concentration.
Correct answer is: Conductivity probe
Q.117 Which type of transformer is used to step down a 220‑V AC supply to 24‑V DC for a bioprocess controller?
Isolation transformer
Power transformer
Audio transformer
Signal transformer
Explanation - An isolation transformer provides both voltage step‑down and safety isolation for the control circuitry.
Correct answer is: Isolation transformer
Q.118 In a fed‑batch fermentation, the primary purpose of a titration loop is to:
Control agitation speed
Add nutrients gradually
Measure pH
Control temperature
Explanation - The titration loop ensures that nutrients are added in a controlled manner, preventing nutrient shock.
Correct answer is: Add nutrients gradually
Q.119 What type of sensor is best for detecting foam build‑up in a fermentation?
pH sensor
Temperature probe
Foam sensor
Conductivity probe
Explanation - Foam sensors detect excessive foam, triggering defoaming actions.
Correct answer is: Foam sensor
Q.120 Which of these devices is most suitable for protecting a bioprocess pump?
Miniature circuit breaker
Ground fault circuit breaker
Fuse
Thermal‑magnetic circuit breaker
Explanation - It protects against overloads and short circuits, ensuring safe operation of the pump.
Correct answer is: Thermal‑magnetic circuit breaker
Q.121 The term 'IP65' signifies for an electrical device used in a fermentation lab:
Operable at 65°C
Protected against water splashes
Dust tight, protected against water jets
Insulated to 6500 V
Explanation - IP65 rating indicates dust‑tight protection and resistance to water jets, suitable for wet environments.
Correct answer is: Dust tight, protected against water jets
Q.122 Which component of a bioprocess control loop is primarily responsible for correcting steady‑state error over time?
Proportional term
Derivative term
Integral term
Reset term
Explanation - The integral action accumulates error over time, eliminating residual steady‑state error.
Correct answer is: Integral term
Q.123 Which of the following is a key advantage of using a digital temperature probe in a fermentation process?
Low cost
High accuracy
No calibration needed
Easy to replace
Explanation - Digital probes provide precise, stable temperature readings crucial for process control.
Correct answer is: High accuracy
Q.124 In a bioprocess, the main advantage of using a 'digital temperature probe' is:
Lower cost
Higher accuracy
No calibration needed
Simple installation
Explanation - Digital probes deliver highly accurate, stable readings essential for precise temperature control.
Correct answer is: Higher accuracy
Q.125 Which of the following sensors is used to monitor the level of liquid in a fermenter?
Temperature probe
Level sensor
pH electrode
Pressure transducer
Explanation - Level sensors detect the liquid height, enabling volume control and monitoring.
Correct answer is: Level sensor
Q.126 In a fed‑batch fermentation, the titration loop is responsible for:
Increasing agitation speed
Adding nutrients gradually
Measuring temperature
Controlling pressure
Explanation - The titration loop ensures a controlled feed of nutrients to maintain growth rates.
Correct answer is: Adding nutrients gradually