Q.1 What is the primary purpose of a bioreactor in a bioprocess?
To separate cells from the product
To provide a controlled environment for biological reactions
To sterilize the feedstock
To convert electrical energy into chemical energy
Explanation - A bioreactor supplies optimal conditions (temperature, pH, oxygen) for microorganisms or cells to produce the desired product.
Correct answer is: To provide a controlled environment for biological reactions
Q.2 Which of the following is NOT a typical mode of operation for a bioreactor?
Batch
Fed‑batch
Continuous
Oscillatory
Explanation - Batch, fed‑batch, and continuous are standard operating modes; oscillatory is not a recognized mode for bioprocesses.
Correct answer is: Oscillatory
Q.3 In a stirred‑tank bioreactor, what is the main function of the impeller?
To heat the medium
To provide mixing and oxygen transfer
To sterilize the vessel
To measure pH
Explanation - The impeller creates turbulence that ensures homogeneous mixing and enhances gas‑liquid mass transfer.
Correct answer is: To provide mixing and oxygen transfer
Q.4 Which parameter is most critical for aerobic microbial growth in a bioreactor?
Dissolved oxygen concentration
Viscosity of the medium
Light intensity
Magnetic field strength
Explanation - Aerobic microbes require sufficient dissolved oxygen; it directly affects their metabolic rate and product formation.
Correct answer is: Dissolved oxygen concentration
Q.5 What does the term 'specific growth rate (μ)' represent?
The rate of product formation per gram of substrate
The rate of cell mass increase per unit cell mass
The rate of temperature change in the reactor
The rate of pH drift over time
Explanation - Specific growth rate (μ) is defined as (1/X)(dX/dt), describing how quickly cells grow relative to their current biomass.
Correct answer is: The rate of cell mass increase per unit cell mass
Q.6 In a fed‑batch process, why is the feed often added gradually?
To prevent substrate inhibition
To increase the reactor volume rapidly
To reduce the temperature
To sterilize the culture
Explanation - Gradual feeding maintains substrate concentration below inhibitory levels, allowing higher cell densities and product yields.
Correct answer is: To prevent substrate inhibition
Q.7 Which of the following is a common method for downstream separation of intracellular products?
Centrifugation followed by cell lysis
Distillation
Electrolysis
Membrane filtration without cell disruption
Explanation - Intracellular products require cell disruption; centrifugation separates the cell debris after lysis.
Correct answer is: Centrifugation followed by cell lysis
Q.8 What is the main advantage of using a continuous stirred‑tank reactor (CSTR) for microbial production?
It allows steady‑state operation with constant product quality
It eliminates the need for sterilization
It requires no agitation
It works only for anaerobic processes
Explanation - CSTRs can maintain a constant environment, leading to consistent productivity and product characteristics.
Correct answer is: It allows steady‑state operation with constant product quality
Q.9 Which kinetic model best describes microbial growth when substrate concentration is low?
Zero‑order kinetics
First‑order kinetics
Monod model
Michaelis‑Menten model
Explanation - The Monod equation relates specific growth rate to substrate concentration, analogous to Michaelis‑Menten but for cells.
Correct answer is: Monod model
Q.10 In bioprocess engineering, what does 'scale‑up' refer to?
Increasing the temperature of the process
Transferring a process from laboratory to industrial scale
Reducing the volume of the reactor
Changing the product type
Explanation - Scale‑up involves adapting conditions and equipment to maintain performance when moving to larger volumes.
Correct answer is: Transferring a process from laboratory to industrial scale
Q.11 Which of the following is a typical sterilization method for bioreactor media?
Filtration through a 0.22 µm membrane
Microwave irradiation
Autoclaving at 121 °C for 15–20 min
UV exposure for 5 seconds
Explanation - Autoclaving is the standard method to ensure sterility of heat‑stable media in bioprocesses.
Correct answer is: Autoclaving at 121 °C for 15–20 min
Q.12 What does the term 'biomass concentration' usually refer to in a fermentation broth?
Amount of dissolved oxygen per liter
Mass of cells per volume of broth (g/L)
Concentration of product per liter
pH of the medium
Explanation - Biomass concentration quantifies the amount of microbial cells present, commonly expressed as g/L.
Correct answer is: Mass of cells per volume of broth (g/L)
Q.13 Which gas is most commonly sparged into an aerobic bioreactor to supply oxygen?
Carbon dioxide
Nitrogen
Air
Helium
Explanation - Air contains about 21 % oxygen and is inexpensive, making it the typical gas for aeration.
Correct answer is: Air
Q.14 What is the purpose of using antifoam agents in bioprocesses?
To increase cell growth rate
To prevent excessive foam formation that can cause contamination or equipment damage
To sterilize the broth
To adjust pH
Explanation - Foam can block sensors and vent lines; antifoams reduce surface tension and limit foam.
Correct answer is: To prevent excessive foam formation that can cause contamination or equipment damage
Q.15 Which analytical technique is most widely used for quantifying glucose concentration in fermentation broth?
High‑performance liquid chromatography (HPLC)
Gas chromatography (GC)
Spectrophotometric glucose oxidase assay
Mass spectrometry
Explanation - The glucose oxidase method provides rapid, specific measurement of glucose in liquid samples.
Correct answer is: Spectrophotometric glucose oxidase assay
Q.16 In a bioprocess, the term 'downstream processing' refers to:
Cell cultivation and growth
Product recovery and purification
Medium preparation
Sterilization of equipment
Explanation - Downstream processing involves separating and purifying the target product after the bioreaction.
Correct answer is: Product recovery and purification
Q.17 Which type of membrane is most suitable for ultrafiltration of proteins from a fermentation broth?
Nanofiltration membrane
Reverse osmosis membrane
Microfiltration membrane
Ultrafiltration membrane
Explanation - Ultrafiltration membranes have pore sizes that retain macromolecules like proteins while allowing smaller solutes to pass.
Correct answer is: Ultrafiltration membrane
Q.18 What is the main reason for controlling pH in a bioreactor?
To prevent corrosion of metal parts
To maintain optimal enzyme activity and cell metabolism
To increase the temperature
To reduce viscosity
Explanation - Enzyme kinetics and cellular processes are highly pH‑dependent, influencing growth and product formation.
Correct answer is: To maintain optimal enzyme activity and cell metabolism
Q.19 Which of the following is a typical product of a yeast fermentation?
Acetone
Ethanol
Lactic acid
Butanol
Explanation - Saccharomyces cerevisiae converts sugars to ethanol and CO₂ under anaerobic conditions.
Correct answer is: Ethanol
Q.20 During a fermentation, a sudden drop in dissolved oxygen (DO) typically indicates:
Overheating of the reactor
Increase in cell density and metabolic activity
Failure of the antifoam system
Loss of sterility
Explanation - More cells consume more oxygen, causing DO to fall if aeration is unchanged.
Correct answer is: Increase in cell density and metabolic activity
Q.21 What does the term 'titer' refer to in bioprocessing?
The concentration of product in the fermentation broth
The speed of agitation
The temperature of the reactor
The volume of the bioreactor
Explanation - Titer is a measure of how much product (e.g., g/L) is present at a given time.
Correct answer is: The concentration of product in the fermentation broth
Q.22 Which of the following is a key advantage of using recombinant DNA technology in bioprocesses?
It eliminates the need for sterilization
It allows the production of proteins that are otherwise difficult to obtain
It reduces the need for oxygen
It increases the size of the bioreactor
Explanation - Recombinant techniques enable expression of foreign genes in host cells, producing valuable proteins like insulin.
Correct answer is: It allows the production of proteins that are otherwise difficult to obtain
Q.23 In a bioprocess, what does the term 'yield' usually denote?
The amount of product formed per unit of substrate consumed
The speed of agitation
The temperature rise over time
The volume of the reactor
Explanation - Yield (Y_P/S) measures process efficiency, indicating how much product is generated from a given substrate.
Correct answer is: The amount of product formed per unit of substrate consumed
Q.24 Which of the following is an example of a downstream purification technique based on size?
Ion‑exchange chromatography
Affinity chromatography
Gel filtration (size‑exclusion) chromatography
Hydrophobic interaction chromatography
Explanation - Gel filtration separates molecules according to size, with larger molecules eluting first.
Correct answer is: Gel filtration (size‑exclusion) chromatography
Q.25 What is the typical range of operating temperature for mesophilic bacterial fermentations?
0‑10 °C
15‑45 °C
50‑70 °C
80‑100 °C
Explanation - Mesophiles grow optimally between ~30‑37 °C, but many processes operate within 15‑45 °C.
Correct answer is: 15‑45 °C
Q.26 Which parameter is most directly affected by changing the agitation speed in a stirred bioreactor?
pH
Dissolved oxygen transfer rate
Substrate concentration
Product molecular weight
Explanation - Higher agitation improves gas‑liquid mass transfer, raising the dissolved oxygen transfer rate.
Correct answer is: Dissolved oxygen transfer rate
Q.27 In a fed‑batch culture, the 'feed strategy' is chosen to:
Maintain a constant pH
Control the rate of substrate addition to optimize growth and product formation
Increase the reactor temperature gradually
Reduce the agitation speed over time
Explanation - Feed strategies (e.g., exponential, constant) are designed to keep substrate levels at desired concentrations.
Correct answer is: Control the rate of substrate addition to optimize growth and product formation
Q.28 Which of the following is NOT a typical step in cell harvesting?
Centrifugation
Filtration
Autoclaving
Flocculation
Explanation - Autoclaving sterilizes but destroys cells; harvesting aims to collect viable cells or biomass.
Correct answer is: Autoclaving
Q.29 What does the term 'biocatalyst' refer to in bioprocess engineering?
A chemical catalyst that speeds up reactions
A microorganism or enzyme that accelerates a biochemical reaction
A heating element in the reactor
A type of filter membrane
Explanation - Biocatalysts are biological entities that lower activation energy, enabling specific transformations under mild conditions.
Correct answer is: A microorganism or enzyme that accelerates a biochemical reaction
Q.30 Which of the following statements about 'sterile filtration' is true?
It removes all dissolved gases from the medium
It can be used to sterilize heat‑sensitive liquids
It sterilizes by heating to 121 °C
It always requires a pore size of 0.45 µm
Explanation - Sterile filtration through 0.22 µm membranes removes microorganisms without applying heat.
Correct answer is: It can be used to sterilize heat‑sensitive liquids
Q.31 What is the main function of a pH probe in a bioreactor control system?
Measure dissolved oxygen
Detect temperature fluctuations
Monitor and maintain the acidity/alkalinity of the culture
Control agitation speed
Explanation - A pH probe provides real‑time data allowing automatic addition of acid/base to keep pH within set limits.
Correct answer is: Monitor and maintain the acidity/alkalinity of the culture
Q.32 Which of the following is a common by‑product of lactic acid fermentation?
Ethanol
Acetone
Lactate
Butyrate
Explanation - Lactic acid bacteria convert sugars primarily into lactic acid (lactate) as the main fermentation product.
Correct answer is: Lactate
Q.33 In a bioprocess, 'mass balance' calculations are essential for:
Determining the mechanical strength of the reactor
Ensuring the conservation of mass of substrates, cells, and products
Adjusting the temperature profile
Setting the alarm thresholds
Explanation - Mass balances track inputs, outputs, and accumulation, crucial for process design and optimization.
Correct answer is: Ensuring the conservation of mass of substrates, cells, and products
Q.34 Which of the following microorganisms is commonly used for recombinant protein production?
Escherichia coli
Streptococcus pneumoniae
Clostridium botulinum
Mycobacterium tuberculosis
Explanation - E. coli is a workhorse host due to its rapid growth, well‑characterized genetics, and ability to express heterologous proteins.
Correct answer is: Escherichia coli
Q.35 What does 'specific productivity (qP)' measure in a bioprocess?
Product formed per unit of time per unit of biomass
Oxygen uptake per hour
Temperature change per minute
pH variation per liter
Explanation - qP = (dP/dt)/X, indicating how efficiently each cell produces the desired product.
Correct answer is: Product formed per unit of time per unit of biomass
Q.36 Which of the following is a typical advantage of using a membrane bioreactor (MBR) over a conventional suspended‑growth system?
Higher oxygen transfer rates without agitation
In‑situ solid‑liquid separation and higher cell densities
Elimination of the need for sterilization
Ability to run at temperatures above 100 °C
Explanation - MBRs combine bioreaction with membrane filtration, retaining cells and enabling high biomass concentrations.
Correct answer is: In‑situ solid‑liquid separation and higher cell densities
Q.37 During a bioprocess, a rise in viscosity is most likely caused by:
Increased temperature
Accumulation of high‑molecular‑weight extracellular polymers
Decrease in agitation speed
Addition of antifoam
Explanation - Polysaccharides or proteins secreted by microbes can increase broth viscosity, affecting mass transfer.
Correct answer is: Accumulation of high‑molecular‑weight extracellular polymers
Q.38 Which type of chromatography relies on the specific binding between an antigen and an antibody?
Ion‑exchange chromatography
Affinity chromatography
Size‑exclusion chromatography
Hydrophobic interaction chromatography
Explanation - Affinity chromatography exploits highly specific interactions, such as antigen‑antibody binding, for purification.
Correct answer is: Affinity chromatography
Q.39 In the context of bioprocesses, the term 'critical quality attribute (CQA)' refers to:
A parameter that directly impacts product safety and efficacy
The temperature setting of the reactor
The brand of equipment used
The cost of raw materials
Explanation - CQAs are defined during product development to ensure the final biopharmaceutical meets required specifications.
Correct answer is: A parameter that directly impacts product safety and efficacy
Q.40 Which of the following best describes the principle of 'oxygen transfer coefficient (kLa)'?
Rate of heat removal from the reactor
Coefficient describing the rate of oxygen diffusion from gas to liquid phase
Measure of pH stability
Ratio of substrate to product
Explanation - kLa quantifies how efficiently oxygen moves from the sparged gas into the liquid, influencing aerobic growth.
Correct answer is: Coefficient describing the rate of oxygen diffusion from gas to liquid phase
Q.41 Which of the following statements about 'autotrophic' microorganisms is true?
They require organic carbon sources for growth
They obtain carbon from CO₂ and use inorganic energy sources
They only grow in the presence of light
They cannot be cultured in bioreactors
Explanation - Autotrophs fix CO₂ into biomass, often using light (photoautotrophs) or inorganic chemicals (chemoautotrophs).
Correct answer is: They obtain carbon from CO₂ and use inorganic energy sources
Q.42 In bioprocess monitoring, which sensor is typically used to measure dissolved oxygen?
Thermocouple
pH electrode
Clark‑type oxygen electrode
Refractometer
Explanation - Clark electrodes are electrochemical sensors that provide accurate real‑time dissolved oxygen readings.
Correct answer is: Clark‑type oxygen electrode
Q.43 What is the primary purpose of a 'seed train' in large‑scale fermentation?
To gradually increase the volume of culture while maintaining cell health
To sterilize the inoculum
To reduce the pH of the medium
To add antifoam agents
Explanation - The seed train scales up inoculum from shake flasks to larger fermenters, ensuring robust growth before production.
Correct answer is: To gradually increase the volume of culture while maintaining cell health
Q.44 Which of the following is an example of a heterologous expression system?
A yeast strain naturally producing ethanol
A plant cell line expressing a bacterial enzyme
A bacterial strain growing on glucose
A mammalian cell line producing its own growth factors
Explanation - Heterologous expression involves producing a gene product in a host different from the original organism.
Correct answer is: A plant cell line expressing a bacterial enzyme
Q.45 During downstream processing, 'diafiltration' is primarily used to:
Increase the concentration of the product
Exchange the buffer or remove low‑molecular‑weight impurities
Sterilize the solution
Adjust the temperature
Explanation - Diafiltration adds fresh solvent while filtering, facilitating buffer exchange or impurity removal.
Correct answer is: Exchange the buffer or remove low‑molecular‑weight impurities
Q.46 Which of the following best describes a 'bioprocess model'?
A diagram of the laboratory layout
A mathematical representation of biological and engineering phenomena in a process
A list of equipment manufacturers
A regulatory compliance checklist
Explanation - Models integrate kinetics, mass transfer, and equipment design to predict process behavior.
Correct answer is: A mathematical representation of biological and engineering phenomena in a process
Q.47 What is the typical purpose of adding a carbon source like glucose to a fed‑batch culture after the exponential growth phase?
To induce product formation in a recombinant system
To lower the pH
To sterilize the broth
To increase agitation speed
Explanation - In many recombinant processes, a carbon source is added after growth to trigger expression of the target protein.
Correct answer is: To induce product formation in a recombinant system
Q.48 Which of the following is a key consideration when selecting a bioreactor material?
Magnetic permeability
Chemical compatibility and sterility
Electrical conductivity
Transparency to visible light
Explanation - Materials must resist corrosion, allow cleaning/sterilization, and not leach contaminants.
Correct answer is: Chemical compatibility and sterility
Q.49 In a bioprocess, 'product inhibition' refers to:
The product increasing the growth rate of cells
The product slowing or stopping its own formation by affecting the cells or enzymes
The product causing the reactor temperature to rise
The product making the broth more viscous
Explanation - High concentrations of product can feedback‑inhibit enzymes or be toxic to cells, reducing yields.
Correct answer is: The product slowing or stopping its own formation by affecting the cells or enzymes
Q.50 Which analytical method is most suitable for determining the molecular weight distribution of a protein product?
Gas chromatography (GC)
Size‑exclusion chromatography (SEC)
Ion‑exchange chromatography
UV‑Vis spectrophotometry
Explanation - SEC separates proteins based on size, allowing estimation of molecular weight and aggregation state.
Correct answer is: Size‑exclusion chromatography (SEC)
Q.51 What is the main purpose of using a 'bioreactor control algorithm' like PID?
To manually adjust temperature
To automatically regulate variables such as pH, temperature, and DO
To calculate the cost of raw materials
To design the reactor geometry
Explanation - PID controllers continuously calculate error and adjust actuators to maintain setpoints.
Correct answer is: To automatically regulate variables such as pH, temperature, and DO
Q.52 Which of the following is a major environmental concern associated with large‑scale bioprocessing?
High CO₂ emissions from combustion
Generation of large volumes of waste broth and spent media
Use of radioactive isotopes
Excessive noise pollution
Explanation - Waste streams require treatment or disposal; reducing them is a key sustainability goal.
Correct answer is: Generation of large volumes of waste broth and spent media
Q.53 In recombinant protein production, which tag is commonly added to facilitate purification?
His‑tag (poly‑histidine)
GFP‑tag
Beta‑lactamase tag
Ribosomal tag
Explanation - His‑tags bind to nickel or cobalt affinity resins, simplifying downstream purification.
Correct answer is: His‑tag (poly‑histidine)
Q.54 What is the typical purpose of a 'temperature ramp' during protein expression in E. coli?
To increase cell viability
To improve protein folding and solubility by lowering temperature after induction
To sterilize the culture
To accelerate substrate consumption
Explanation - Reducing temperature after induction often reduces inclusion body formation and yields more soluble protein.
Correct answer is: To improve protein folding and solubility by lowering temperature after induction
Q.55 Which of the following best describes 'process validation' in biomanufacturing?
Testing the final product for potency only
Demonstrating that the process consistently produces a product meeting its specifications
Measuring the temperature of the reactor
Designing a new bioreactor
Explanation - Validation provides documented evidence that the process is reliable, reproducible, and compliant.
Correct answer is: Demonstrating that the process consistently produces a product meeting its specifications
Q.56 Which term describes the ratio of the volume of the feed added per unit time to the reactor volume in a continuous process?
Dilution rate (D)
Specific growth rate (μ)
Yield coefficient (Y)
Productivity (qP)
Explanation - D = F/V (feed flow rate divided by reactor volume) determines residence time in continuous culture.
Correct answer is: Dilution rate (D)
Q.57 In the context of bioprocess safety, what does 'containment level' refer to?
The temperature range of operation
The biosafety level (BSL) required to handle the organism
The size of the bioreactor
The amount of antifoam added
Explanation - Containment levels (BSL‑1 to BSL‑4) define safety practices based on organism pathogenicity.
Correct answer is: The biosafety level (BSL) required to handle the organism
Q.58 Which of the following is a primary benefit of using a 'single‑use' (disposable) bioreactor?
Higher pressure tolerance
Elimination of cleaning and sterilization steps between batches
Ability to run at temperatures above 200 °C
Improved magnetic properties
Explanation - Single‑use systems reduce turnaround time, cross‑contamination risk, and labor associated with cleaning.
Correct answer is: Elimination of cleaning and sterilization steps between batches
Q.59 What does the term 'critical process parameter (CPP)' refer to?
A variable that has a direct impact on a critical quality attribute
The cost of raw materials
The brand of sensors used
The color of the reactor vessel
Explanation - CPPs are controlled during manufacturing to ensure CQAs are met.
Correct answer is: A variable that has a direct impact on a critical quality attribute
Q.60 In a fermentation, why might a researcher add a 'co‑factor' such as NAD⁺ to the medium?
To act as an antifoam agent
To provide a necessary component for enzyme activity and metabolic pathways
To increase the temperature
To change the pH
Explanation - Co‑factors are essential for certain enzymatic reactions; adding them can enhance productivity.
Correct answer is: To provide a necessary component for enzyme activity and metabolic pathways
Q.61 Which method is most appropriate for measuring the concentration of a recombinant protein in the supernatant?
Bradford assay
BOD test
Gravimetric analysis
Titration
Explanation - The Bradford assay provides rapid, colorimetric quantification of total protein, suitable for recombinant products.
Correct answer is: Bradford assay
Q.62 Which of the following describes the 'lag phase' in microbial growth curves?
Rapid exponential increase in cell numbers
Period of adaptation where cells prepare for division
Decline in cell numbers due to nutrient depletion
Stationary phase where growth ceases
Explanation - During lag, cells adjust to new conditions before entering exponential growth.
Correct answer is: Period of adaptation where cells prepare for division
Q.63 In bioprocess scale‑up, maintaining constant 'oxygen transfer rate (OTR)' often requires:
Increasing reactor volume without changing agitation
Adjusting agitation speed and sparge rate to match the larger volume
Reducing temperature
Adding more antifoam
Explanation - OTR depends on kLa, which is influenced by agitation and gas flow; both must be scaled appropriately.
Correct answer is: Adjusting agitation speed and sparge rate to match the larger volume
Q.64 Which of the following is a common strategy to reduce proteolytic degradation of a secreted recombinant protein?
Increasing the temperature to 45 °C
Using host strains deficient in proteases
Adding more glucose to the medium
Increasing agitation speed
Explanation - Protease‑deficient strains limit degradation, enhancing product stability.
Correct answer is: Using host strains deficient in proteases
Q.65 What is the main function of a 'peristaltic pump' in a fed‑batch bioreactor?
To provide sterile filtration
To deliver precise volumes of feed medium into the reactor
To measure pH
To control temperature
Explanation - Peristaltic pumps can accurately and aseptically add feed without contaminating the culture.
Correct answer is: To deliver precise volumes of feed medium into the reactor
Q.66 Which of the following statements about 'bioreactor scale‑down models' is correct?
They are larger than the production reactor
They replicate key phenomena of the large‑scale system for testing and optimization
They are only used for waste treatment
They do not require any sensors
Explanation - Scale‑down models mimic gradients, mixing, and mass transfer of the full‑scale plant to study performance.
Correct answer is: They replicate key phenomena of the large‑scale system for testing and optimization
Q.67 In bioprocess engineering, the term 'holdup' refers to:
The amount of solid material that remains in the reactor at any time
The temperature increase due to agitation
The electrical power consumed
The amount of light absorbed by the culture
Explanation - Holdup is the inventory of material (cells, substrate, product) present inside the reactor.
Correct answer is: The amount of solid material that remains in the reactor at any time
Q.68 Which of the following is a typical reason to use a 'temperature‑controlled' (cryogenic) bioreactor?
To grow thermophilic organisms
To maintain low temperatures for psychrophilic microorganisms or enzyme stability
To increase the rate of foam formation
To sterilize the reactor
Explanation - Cold‑adapted processes require precise temperature control below ambient levels.
Correct answer is: To maintain low temperatures for psychrophilic microorganisms or enzyme stability
Q.69 What does the term 'substrate inhibition' mean in microbial kinetics?
Growth rate increases indefinitely with substrate concentration
High substrate concentrations decrease the specific growth rate
Substrate is completely consumed within minutes
Substrate changes the pH of the medium
Explanation - Excess substrate can be toxic or cause metabolic imbalances, reducing growth.
Correct answer is: High substrate concentrations decrease the specific growth rate
Q.70 In a chromatography step, a 'gradient elution' is used to:
Maintain a constant buffer composition
Gradually change the buffer composition to improve separation of compounds
Increase the temperature linearly
Reduce the flow rate over time
Explanation - Gradient elution alters mobile‑phase strength, allowing differential elution of bound species.
Correct answer is: Gradually change the buffer composition to improve separation of compounds
Q.71 Which of the following is an advantage of using a 'continuous perfusion' system over traditional batch culture?
Higher cell densities and steady product formation
No need for sterilization
Simpler equipment design
Lower energy consumption
Explanation - Perfusion continuously removes product while retaining cells, enabling high productivity.
Correct answer is: Higher cell densities and steady product formation
Q.72 What is the primary reason for performing a 'sterility test' on a final biopharmaceutical product?
To verify the product's color
To ensure no viable microorganisms are present, guaranteeing safety
To measure the product's pH
To determine the viscosity
Explanation - Regulatory standards require proof that injectable products are free of contaminating microbes.
Correct answer is: To ensure no viable microorganisms are present, guaranteeing safety
Q.73 Which of the following is a typical feature of 'high‑cell‑density fermentation' (HCDF)?
Operation at very low substrate concentrations
Use of fed‑batch or perfusion strategies to achieve cell densities >100 g/L
Running at temperatures above 80 °C
Eliminating the need for oxygen
Explanation - HCDF employs controlled feeding or cell retention to reach very high biomass levels.
Correct answer is: Use of fed‑batch or perfusion strategies to achieve cell densities >100 g/L
Q.74 In the context of bioprocesses, what does 'glycosylation' refer to?
Addition of phosphate groups to proteins
Attachment of carbohydrate chains to proteins, influencing stability and activity
Removal of amino acids from a peptide
Denaturation of enzymes
Explanation - Glycosylation is a post‑translational modification crucial for many therapeutic proteins.
Correct answer is: Attachment of carbohydrate chains to proteins, influencing stability and activity
Q.75 Which of the following is a common indicator that a fermentation has entered the stationary phase?
Rapid increase in dissolved oxygen
Plateau in biomass concentration despite continued substrate consumption
Sharp rise in temperature
Sudden drop in pH
Explanation - In stationary phase, growth ceases while metabolic activity may persist, leading to product formation.
Correct answer is: Plateau in biomass concentration despite continued substrate consumption
Q.76 What is the purpose of a 'blank' sample in analytical assays such as HPLC?
To calibrate the temperature sensor
To correct for background signal and ensure accurate quantification
To increase the flow rate
To sterilize the column
Explanation - A blank contains all reagents except the analyte, allowing subtraction of baseline noise.
Correct answer is: To correct for background signal and ensure accurate quantification
Q.77 In a bioprocess, why might a researcher choose to operate at a higher pH (e.g., pH 8) for a specific enzyme reaction?
The enzyme exhibits optimal activity at that pH
Higher pH always increases cell growth
It reduces the need for antifoam
It increases the temperature automatically
Explanation - Enzyme kinetics are pH‑dependent; operating at the optimal pH maximizes catalytic efficiency.
Correct answer is: The enzyme exhibits optimal activity at that pH
Q.78 Which of the following best describes the term 'bioprocess economics'?
The study of electrical power consumption in a plant
Analysis of costs, yields, and profitability of biotechnological production
The calculation of reactor dimensions only
The design of laboratory safety protocols
Explanation - Bioprocess economics evaluates the financial feasibility of scaling and operating a biomanufacturing process.
Correct answer is: Analysis of costs, yields, and profitability of biotechnological production
Q.79 Which of the following is a typical characteristic of a 'thermophilic' microorganism used in industrial bioprocesses?
Optimal growth temperature between 45–80 °C
Requires light for growth
Produces large amounts of lactic acid at low pH
Cannot survive in the presence of oxygen
Explanation - Thermophiles thrive at high temperatures, offering advantages such as reduced contamination risk.
Correct answer is: Optimal growth temperature between 45–80 °C
Q.80 What is the main advantage of using a 'dual‑stage' fermentation strategy?
It allows separate optimization of growth and product formation phases
It eliminates the need for pH control
It reduces the need for sterilization
It increases the reactor’s volume automatically
Explanation - Dual‑stage processes can first maximize biomass, then shift conditions to favor product synthesis.
Correct answer is: It allows separate optimization of growth and product formation phases
Q.81 Which of the following is an example of a 'bio‑catalytic' process?
Catalytic cracking of petroleum
Enzymatic conversion of starch to glucose
Electroplating of metals
Thermal cracking of polymers
Explanation - Bio‑catalysis uses enzymes or whole cells to drive chemical transformations under mild conditions.
Correct answer is: Enzymatic conversion of starch to glucose
Q.82 In bioprocess scale‑up, which similarity criterion is most often maintained for mixing?
Constant Reynolds number (Re)
Constant temperature
Constant pH
Constant oxygen concentration
Explanation - Maintaining Re helps ensure comparable flow regimes and mixing characteristics across scales.
Correct answer is: Constant Reynolds number (Re)
Q.83 Which of the following statements about 'cell line development' for biopharmaceutical production is correct?
It involves selecting a host that can produce high yields of the desired protein with appropriate post‑translational modifications
It always uses bacterial cells
It does not affect downstream purification
It only concerns the color of the cells
Explanation - Choosing the right cell line (e.g., CHO, HEK293) is critical for product quality and yield.
Correct answer is: It involves selecting a host that can produce high yields of the desired protein with appropriate post‑translational modifications
Q.84 What is the purpose of performing a 'mass balance' on a fed‑batch fermentation after the run?
To calculate the total amount of substrate, biomass, and product to assess efficiency
To determine the color of the broth
To adjust the temperature for the next batch
To change the reactor material
Explanation - Post‑run mass balances verify material accounting and identify losses or deviations.
Correct answer is: To calculate the total amount of substrate, biomass, and product to assess efficiency
Q.85 Which of the following is a common method for removing endotoxins from a protein product?
Ion‑exchange chromatography
Gel filtration chromatography
Ultrafiltration with a 0.22 µm membrane
Distillation
Explanation - Ion‑exchange can effectively bind negatively charged endotoxins, separating them from the target protein.
Correct answer is: Ion‑exchange chromatography
Q.86 In a bioprocess, a high 'specific oxygen uptake rate (qO₂)' indicates:
Low metabolic activity of cells
High metabolic activity and demand for oxygen
Excessive temperature
Insufficient mixing
Explanation - qO₂ measures oxygen consumption per unit biomass; higher values reflect vigorous aerobic metabolism.
Correct answer is: High metabolic activity and demand for oxygen
Q.87 Which of the following is a typical reason to add a 'metal chelator' such as EDTA to a fermentation medium?
To increase viscosity
To bind trace metals that might inhibit cell growth or cause unwanted side reactions
To raise the pH dramatically
To sterilize the medium
Explanation - Chelators sequester metal ions, preventing toxicity or interference with enzymes.
Correct answer is: To bind trace metals that might inhibit cell growth or cause unwanted side reactions
Q.88 Which of the following best describes the term 'bioprocess integration'?
Connecting upstream and downstream steps to streamline the overall process
Installing more sensors in the reactor
Increasing the reactor size
Changing the color of the product
Explanation - Integration seeks to reduce time, cost, and waste by coordinating all stages of production.
Correct answer is: Connecting upstream and downstream steps to streamline the overall process
Q.89 In bioprocess control, what does the term 'setpoint' refer to?
The maximum temperature the reactor can reach
The desired target value for a process variable (e.g., pH, temperature)
The volume of the bioreactor
The speed of the agitator
Explanation - Control systems aim to keep variables at their setpoints for optimal operation.
Correct answer is: The desired target value for a process variable (e.g., pH, temperature)
Q.90 Which of the following is a primary challenge when scaling up a membrane‑based separation step?
Increasing the reactor pressure
Maintaining flux and avoiding fouling at larger membrane areas
Changing the pH of the feed
Reducing the temperature
Explanation - Scale‑up can lead to reduced flux and higher fouling; design must address these issues.
Correct answer is: Maintaining flux and avoiding fouling at larger membrane areas
Q.91 What is the main advantage of using a 'synthetic' medium over a 'complex' medium in recombinant protein production?
It is cheaper to produce
It provides defined composition, facilitating reproducibility and downstream purification
It contains more nutrients
It eliminates the need for sterilization
Explanation - Defined media reduce variability and simplify purification by eliminating unknown components.
Correct answer is: It provides defined composition, facilitating reproducibility and downstream purification
Q.92 In the context of bioprocess monitoring, what does the acronym 'PAT' stand for?
Process Analytical Technology
Protein Activity Test
Pressure and Temperature
Partial Air Transfer
Explanation - PAT refers to systems for real‑time monitoring and control of critical process parameters.
Correct answer is: Process Analytical Technology
Q.93 Which of the following is an example of a 'low‑cost' downstream technique suitable for pilot‑scale purification?
Affinity chromatography
Ammonium sulfate precipitation
Supercritical fluid extraction
High‑performance liquid chromatography (HPLC)
Explanation - Salting‑out is inexpensive and can concentrate proteins before finer purification steps.
Correct answer is: Ammonium sulfate precipitation
Q.94 Which parameter is most directly influenced by the 'sparge rate' in an aerobic bioreactor?
pH stability
Dissolved oxygen concentration
Agitation speed
Viscosity of the broth
Explanation - Increasing sparge rate delivers more gas bubbles, raising dissolved oxygen levels.
Correct answer is: Dissolved oxygen concentration
Q.95 What is the purpose of adding a 'buffer' to the fermentation medium?
To provide a carbon source
To maintain pH stability during metabolic activity
To increase temperature
To generate foam
Explanation - Buffers resist pH changes caused by acid or base production during growth.
Correct answer is: To maintain pH stability during metabolic activity
Q.96 Which of the following best describes 'bioprocess intensification'?
Running processes at larger volumes only
Increasing productivity per unit volume through higher cell densities, faster rates, or improved yields
Decreasing the number of steps in downstream processing
Using only renewable energy sources
Explanation - Intensification aims to get more product from the same equipment footprint.
Correct answer is: Increasing productivity per unit volume through higher cell densities, faster rates, or improved yields
Q.97 In a bioprocess, what does 'glycolysis' refer to?
The conversion of glucose to pyruvate with the generation of ATP
The synthesis of proteins from amino acids
The breakdown of lipids into fatty acids
The conversion of CO₂ into glucose
Explanation - Glycolysis is the central pathway for carbohydrate catabolism in most cells.
Correct answer is: The conversion of glucose to pyruvate with the generation of ATP
Q.98 Which of the following is a key reason to use a 'perfusion' bioreactor for monoclonal antibody production?
It eliminates the need for a seed train
It allows continuous removal of product, reducing degradation and increasing overall yield
It works only at low temperatures
It does not require oxygen
Explanation - Perfusion keeps product fresh and reduces residence time, improving quality and yield.
Correct answer is: It allows continuous removal of product, reducing degradation and increasing overall yield
Q.99 What is the main advantage of using a 'microbial cell factory' over a plant‑based system for small‑molecule production?
Higher growth rates and easier genetic manipulation
Ability to grow in the dark
Lower oxygen requirements
Production of larger proteins
Explanation - Microbes reproduce quickly and can be engineered straightforwardly, making them efficient production platforms.
Correct answer is: Higher growth rates and easier genetic manipulation
Q.100 Which of the following is an example of a 'critical raw material' in bioprocess manufacturing?
The stainless‑steel reactor
The water used for cleaning
The defined growth medium components like amino acids
The paint on the facility walls
Explanation - Raw materials that directly affect product quality, such as nutrients, are considered critical and must be controlled.
Correct answer is: The defined growth medium components like amino acids
Q.101 What is the primary function of a 'heat exchanger' in a downstream purification train?
To sterilize the product
To control temperature during chromatography or crystallization steps
To increase viscosity
To adjust pH
Explanation - Temperature influences solubility and binding; heat exchangers maintain desired conditions.
Correct answer is: To control temperature during chromatography or crystallization steps
Q.102 In a fed‑batch process, the term 'exponential feeding' means:
Feeding at a constant rate
Increasing feed rate exponentially to match the exponential growth of cells
Feeding only at the start of the batch
Stopping feed after a fixed time
Explanation - Exponential feeding supplies substrate at a rate that keeps its concentration relatively constant during exponential growth.
Correct answer is: Increasing feed rate exponentially to match the exponential growth of cells
Q.103 Which of the following is a common method for monitoring cell viability during a fermentation?
Measuring dissolved oxygen
Using a trypan blue exclusion assay
Measuring temperature
Measuring reactor pressure
Explanation - Trypan blue stains dead cells, allowing viability assessment via microscopy or flow cytometry.
Correct answer is: Using a trypan blue exclusion assay
Q.104 What is the main purpose of a 'sterile vent filter' on a bioreactor?
To allow gas exchange while preventing microbial ingress
To filter the product stream
To sterilize the liquid medium
To reduce foam formation
Explanation - Vent filters maintain pressure balance and enable aeration while protecting the culture from contamination.
Correct answer is: To allow gas exchange while preventing microbial ingress