I85PREP
⌘ K
Craftsman Bio Process study materials
Craftsman Bio Process study resources

Craftsman Bio Process practice questions

One question at a time. Build your Craftsman Bio Process understanding.

First 50 of 199 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Preparation

In a bioprocess, which term describes the vessel in which cells or microorganisms are cultivated under controlled conditions to produce a product?

  1. Centrifuge
  2. Chromatography column
  3. Bioreactor Correct answer.
  4. Lyophilizer

Explanation

A bioreactor is the controlled cultivation vessel where cells or microorganisms grow and generate product; temperature, pH, aeration, and agitation are regulated inside it. The other listed devices are downstream separation or drying units, not cultivation vessels.

Question 2Preparation

Which parameter is most directly controlled to maintain dissolved oxygen at a setpoint in an aerobic stirred-tank bioreactor?

  1. Harvest valve position
  2. Buffer pH after clarification
  3. Column bed height
  4. Agitation rate and inlet gas composition Correct answer.

Explanation

Dissolved oxygen depends on oxygen transfer rate, which is governed by agitation and sparged gas composition. Increasing agitation or enriching inlet gas with oxygen raises the transfer rate to hold the DO setpoint. The other options are downstream or unrelated variables.

Question 3Preparation

What is the primary purpose of a seed train in a bioprocess?

  1. To concentrate the harvested broth
  2. To expand cell mass through successive stages before inoculating the production bioreactor Correct answer.
  3. To sterilize the production vessel with steam
  4. To purify the product using affinity resin

Explanation

A seed train sequentially scales up viable cell mass in progressively larger vessels so the production bioreactor receives an adequate, healthy inoculum. Each stage shortens the growth time needed at production scale and reduces risk of contamination.

Question 4Preparation

During a fed-batch run, glucose is added gradually rather than charged all at once at inoculation. What is the main reason for this feeding strategy?

  1. To shorten the batch by removing the need for a growth phase
  2. To keep the vessel pressure below atmospheric
  3. To eliminate the requirement for pH control
  4. To limit substrate concentration and avoid overflow metabolism such as acetate accumulation Correct answer.

Explanation

Fed-batch feeding keeps residual substrate low, preventing overflow metabolism and byproduct accumulation such as acetate in E. coli, while still supplying carbon for growth and product formation. It also extends productive culture time compared with batch operation.

Question 5Preparation

A culture shows a rapid rise in lactate that coincides with a drop in dissolved oxygen below the setpoint. Which corrective action is most appropriate first?

  1. Lower the temperature to 4 degrees Celsius
  2. Increase oxygen transfer by raising agitation or enrichment, then reassess Correct answer.
  3. Stop pH control to reduce base addition
  4. Add more glucose to boost growth

Explanation

A DO drop with lactate accumulation signals oxygen limitation driving anaerobic metabolism. Restoring oxygen transfer through agitation or gas enrichment addresses the root cause before other adjustments. Adding feed or stopping pH control would worsen the imbalance.

Question 6Preparation

Which measurement is used to estimate viable cell density in a mammalian culture when distinguishing live from dead cells is required?

  1. Trypan blue exclusion with automated image counting Correct answer.
  2. Wet cell weight after centrifugation
  3. Turbidity at 600 nm alone
  4. Conductivity of the broth

Explanation

Trypan blue exclusion relies on intact membranes of viable cells excluding the dye, allowing live and dead cells to be counted separately by image-based instruments. Turbidity and wet weight measure total biomass without discriminating viability.

Question 7Preparation

What does the term multiplicity of infection (MOI) represent in a viral vector production process?

  1. The ratio of infectious virus particles to target cells at infection Correct answer.
  2. The number of harvest cycles per batch
  3. The ratio of medium volume to vessel volume
  4. The fraction of product lost during filtration

Explanation

MOI is the number of infectious viral particles introduced per target cell, a key variable affecting infection efficiency and yield. Optimizing MOI balances transduction against resource use and cell stress.

Question 8Preparation

A harvest stream is clarified using a depth filter followed by a sterile filter. What is the main purpose of the depth filter in this sequence?

  1. To remove cells and larger debris and protect the downstream sterile filter Correct answer.
  2. To exchange buffer salts
  3. To bind the product by affinity
  4. To concentrate the product by ultrafiltration

Explanation

Depth filters capture cells, aggregates, and particulate debris within a fibrous matrix, reducing the particle load reaching the sterile filter. This protects the final filter from premature fouling and extends its throughput.

Question 9Preparation

In a Protein A capture step for a monoclonal antibody, what interaction primarily drives binding of the antibody to the resin?

  1. Ion exchange between charged side chains
  2. Binding of the Fc region to the immobilized Protein A ligand Correct answer.
  3. Reverse-phase hydrophobic interaction
  4. Size exclusion by pore diffusion

Explanation

Protein A binds the Fc region of most IgG antibodies with high affinity, enabling selective capture while impurities flow through. Elution is typically achieved by lowering pH to disrupt that interaction.

Question 10Preparation

Why is low pH hold commonly performed after Protein A elution in antibody manufacturing?

  1. To increase the antibody binding capacity of the resin
  2. To precipitate buffer salts for removal
  3. To inactivate enveloped viruses as a viral clearance step Correct answer.
  4. To sterilize the chromatography column

Explanation

A low pH hold is a well-established viral inactivation step that disrupts enveloped virus particles while the antibody generally remains stable. The pH and duration are validated to demonstrate adequate inactivation.

Question 11Preparation

Which chromatographic mode separates molecules primarily on the basis of differences in net surface charge?

  1. Ion exchange chromatography Correct answer.
  2. Hydrophobic interaction chromatography
  3. Size exclusion chromatography
  4. Affinity chromatography

Explanation

Ion exchange chromatography binds molecules according to their net charge at a given pH, with elution driven by salt or pH gradients. Molecules with different charge profiles elute at different conductivities.

Question 12Preparation

During ultrafiltration/diafiltration, what does the diafiltration step accomplish?

  1. It sterilizes the product stream
  2. It increases the product concentration only
  3. It exchanges the buffer while retaining the product by membrane size Correct answer.
  4. It removes the product into the permeate

Explanation

Diafiltration adds fresh buffer while permeate is removed, washing small molecules through the membrane and exchanging the product into the desired formulation buffer. The membrane retains the product by molecular weight cutoff.

Question 13Preparation

What is the purpose of a tangential flow filtration (TFF) retentate control during concentration?

  1. To convert the product into a solid powder
  2. To increase the vessel temperature above setpoint
  3. To maintain a stable transmembrane pressure and limit membrane fouling Correct answer.
  4. To eliminate the need for a pump

Explanation

In TFF, controlling retentate flow and permeate flux keeps transmembrane pressure within a range that limits concentration polarization and fouling. This preserves product yield and membrane performance.

Question 14Preparation

Which formulation approach is typically chosen to stabilize a protein drug substance for long-term storage as a liquid?

  1. Storing the protein at high ionic strength without buffer
  2. Exposing the solution to repeated freeze-thaw cycles
  3. Adding excipients such as buffer, sugar, and surfactant at an optimized pH Correct answer.
  4. Heating the solution to near boiling to remove water

Explanation

Liquid protein formulations use buffering agents, lyoprotectants or stabilizers like sugars, and surfactants to reduce aggregation and surface adsorption at a defined pH. These excipients maintain conformational and colloidal stability during storage.

Question 15Preparation

In a lyophilization cycle, what happens during the primary drying phase?

  1. The product melts into a liquid and is then spray dried
  2. Excipients are chemically cross-linked
  3. The vial is sealed before any water is removed
  4. Frozen water sublimes under reduced pressure while the product stays below its collapse temperature Correct answer.

Explanation

Primary drying removes ice by sublimation at low pressure while the product temperature remains below its collapse or eutectic temperature to preserve cake structure. Secondary drying then removes bound water.

Question 16Preparation

A batch record shows the production bioreactor was inoculated at a viable cell density far below the target. Which downstream effect is most likely?

  1. Immediate increase in product titer
  2. Reduced need for feed addition
  3. A longer growth phase and delayed harvest, potentially altering product quality Correct answer.
  4. Higher dissolved oxygen transfer efficiency

Explanation

Starting with fewer viable cells extends the time needed to reach target density, shifting the harvest schedule and potentially changing product quality attributes. It does not raise titer or reduce nutrient demand.

Question 17Preparation

What is the role of a sterilizing-grade filter in bioprocessing?

  1. To exchange buffer components
  2. To concentrate the product by ultrafiltration
  3. To remove host cell proteins by affinity
  4. To remove microorganisms from a liquid or gas stream to a defined sterility assurance level Correct answer.

Explanation

Sterilizing-grade filters, typically rated at 0.2 micrometer, are validated to remove bacteria and provide a defined sterility assurance level for fluids and gases. They do not perform purification or buffer exchange.

Question 18Preparation

Which cleaning approach is commonly used for a stainless steel bioreactor between campaigns to remove process residues and reduce bioburden?

  1. Clean-in-place with alkaline detergent followed by rinse and sanitization Correct answer.
  2. Manual dry wiping without rinsing
  3. Sealing the vessel without cleaning
  4. Flushing with product buffer only

Explanation

Clean-in-place cycles circulate alkaline detergent to dissolve residues, followed by rinses and a sanitization step to control bioburden. Validation confirms removal of product and cleaning agent residues.

Question 19Preparation

A chromatographic elution peak shows increased turbidity and a pressure rise across the column. What is the most likely cause?

  1. An increase in product purity
  2. A calibration error in the pH probe
  3. A decrease in buffer conductivity
  4. Precipitation or aggregation of protein causing column fouling Correct answer.

Explanation

Turbidity with rising column pressure indicates particulate formation, often from protein precipitation or aggregation blocking the resin bed. Adjusting elution conditions and including a filtration step can mitigate the issue.

Question 20Preparation

Which scale-up consideration is most important when transferring a mixing-sensitive fed-batch process from a small bioreactor to a larger one?

  1. Matching power input per volume or tip speed to preserve mixing and oxygen transfer Correct answer.
  2. Matching the vessel serial number
  3. Keeping the same operator shift schedule
  4. Using the same lot of gloves

Explanation

Mixing-sensitive processes require matching a meaningful engineering parameter such as power per volume or tip speed so that oxygen transfer, nutrient dispersion, and shear remain comparable across scales. Without this, gradients and stress can alter metabolism.

Question 21Preparation

What is the function of an antifoam addition in a high-cell-density fermentation?

  1. To reduce foam formation that can foul filters and reduce working volume Correct answer.
  2. To sterilize the vessel
  3. To increase the dissolved oxygen setpoint
  4. To raise the pH setpoint

Explanation

Foaming in aerated, high-density cultures can clog exhaust filters and reduce usable volume; antifoam agents lower surface tension to control foam. Addition must be controlled to avoid negative effects on oxygen transfer.

Question 22Preparation

During harvest, a centrifuge is run at excessive feed rate. Which outcome is most likely?

  1. Incomplete solid separation and higher particle load on downstream filters Correct answer.
  2. Improved clarification and longer filter life
  3. Lower shear exposure to cells
  4. Increased product purity in the centrate

Explanation

Exceeding the centrifuge's solids-handling capacity shortens residence time, so cells and debris remain in the centrate and burden downstream filters. Feed rate must be balanced against separation performance.

Question 23Preparation

Which document in a regulated bioprocess defines the steps, parameters, and acceptance criteria for manufacturing a batch?

  1. The equipment vendor manual
  2. The master batch record Correct answer.
  3. The material safety data sheet
  4. The marketing brochure

Explanation

The master batch record specifies approved process steps, critical parameters, and acceptance criteria, and it governs execution of production batches. Executed copies become the batch record used for release review.

Question 24Preparation

A deviation occurs when the bioreactor temperature exceeded the validated range for several hours. What is the appropriate next step in a quality system?

  1. Document the deviation, assess product impact, and determine disposition through investigation Correct answer.
  2. Continue release without evaluation
  3. Adjust the setpoint and take no further action
  4. Discard all records to avoid audit findings

Explanation

Excursions outside validated ranges must be documented and investigated to assess impact on product quality, with disposition decided through the quality system. Ignoring the event or hiding records violates data integrity and GMP expectations.

Question 25Preparation

What does a mass balance around a chromatography step help verify?

  1. That the resin has an unlimited lifetime
  2. That the column was manufactured correctly
  3. That the amount of product and impurities entering matches what is recovered, retained, or discarded Correct answer.
  4. That the buffer pH is always neutral

Explanation

A mass balance compares material entering the step with material in pools, waste, and holdup, confirming that losses and recovery are understood. Discrepancies can reveal analytical errors, leaks, or unaccounted product.

Question 26Preparation

In a seed train for a CHO cell process, which parameter is most commonly used to decide when to passage a culture into the next vessel?

  1. Viable cell density and viability measured by trypan blue or a similar counting method Correct answer.
  2. The turbidity of the medium measured at 600 nm as the sole indicator
  3. The concentration of lactate dehydrogenase released into the spent medium
  4. The osmolality of the harvested culture fluid

Explanation

Seed train transfer decisions in mammalian processes rely on viable cell density and percent viability, typically measured by trypan blue exclusion or an automated image-based counter. These values indicate whether the culture has reached a density that supports inoculation of the next stage at the target seeding density.

Question 27Preparation

A fed-batch bioreactor is fed a concentrated nutrient solution. What is the primary purpose of controlling the feed rate rather than adding all nutrients at inoculation?

  1. To avoid substrate inhibition and overflow metabolism while sustaining growth and productivity Correct answer.
  2. To shorten the length of the production phase
  3. To eliminate the need for dissolved oxygen control
  4. To reduce the total mass of nutrients required for the batch

Explanation

Fed-batch feeding keeps glucose and other key substrates at low, growth-limiting concentrations so that overflow metabolism, such as lactate accumulation, is minimized. Controlled feeding also avoids osmotic and inhibitory stress from high initial nutrient levels.

Question 28Preparation

A process development scientist records the specific productivity of a CHO culture as pg/cell/day. Which quantity is being expressed?

  1. The ratio of product to total host cell protein in the harvest
  2. The product concentration at harvest divided by the peak viable cell density
  3. The amount of product formed per viable cell per unit time Correct answer.
  4. The volumetric titer divided by the culture duration

Explanation

Specific productivity normalizes product formation to the number of producing cells and to time, giving pg/cell/day. It isolates cellular output from the effect of biomass, which makes it useful for comparing clones and conditions.

Question 29Preparation

During a production run, the dissolved oxygen setpoint is maintained by cascading to agitator speed. What is the main risk of relying solely on agitation to control DO at large scale?

  1. The pH setpoint will drift as a direct consequence
  2. Foam generation is eliminated, removing the need for antifoam
  3. The probe response time becomes too fast for the controller
  4. Excessive shear and increased oxygen transfer demand can stress cells and damage sensitive molecules Correct answer.

Explanation

Increasing agitation raises the power input and shear environment experienced by cells. At large scale the tip speed and local energy dissipation can become damaging, so oxygen supply is usually balanced across sparging and agitation rather than agitation alone.

Question 30Preparation

A bioreactor shows a sudden drop in viable cell density accompanied by rising lactate and falling pH. Which investigation is most appropriate first?

  1. Add antifoam to suppress foam accumulation
  2. Increase the agitation rate to improve mixing immediately
  3. Check for contamination and review the feed and glucose addition records for an overfeed event Correct answer.
  4. Reduce the sparging rate to lower oxygen delivery

Explanation

A rapid viability decline with lactate accumulation and acidification is consistent with either microbial contamination or a metabolic shift from substrate overfeeding. Both are addressed by checking sterility and reviewing feed records before changing operating parameters.

Question 31Preparation

Which parameter is typically held constant when performing a scale-down model of a production bioreactor to study process robustness?

  1. Power input per unit volume and the resulting mixing and oxygen transfer characteristics Correct answer.
  2. The absolute sparging flow rate in liters per minute
  3. The absolute impeller tip speed in meters per second
  4. The geometric volume of the vessel

Explanation

Scale-down models aim to reproduce the physical environment of the large vessel, which is best captured by matching power input per volume, and thereby mixing time and oxygen transfer. Matching absolute tip speed or absolute flows does not preserve these characteristics across scales.

Question 32Preparation

A perfusion culture uses a cell retention device. Which operating parameter most directly determines the cell-specific perfusion rate?

  1. The perfusion flow rate divided by the viable cell density and the working volume Correct answer.
  2. The transmembrane pressure across the retention filter
  3. The antifoam addition rate
  4. The concentration of glucose in the feed medium

Explanation

The cell-specific perfusion rate expresses the medium exchange rate per cell and is calculated from the perfusion flow rate normalized to viable cell density and bioreactor working volume. It is used to ensure adequate nutrient supply without excessive medium consumption.

Question 33Preparation

Which in-process measurement is most useful for confirming that a chromatography column has been adequately equilibrated before loading?

  1. The pH and conductivity of the column effluent compared with the equilibration buffer specification Correct answer.
  2. The UV absorbance of the load material at 280 nm
  3. The turbidity of the elution pool
  4. The pressure drop across the column during elution

Explanation

Equilibration is confirmed when the effluent pH and conductivity match the equilibration buffer, indicating the mobile phase throughout the bed has reached the intended condition. UV absorbance of the load and pressure drop during elution describe other stages of the operation.

Question 34Preparation

A virus filtration step is placed after the final chromatography step. Why is this position chosen in a typical antibody platform process?

  1. It replaces the need for a low pH viral inactivation step
  2. It increases the overall product titer of the process
  3. It improves the binding capacity of the preceding chromatography column
  4. It removes potential viral contaminants after most impurities have been cleared and close to the final product Correct answer.

Explanation

Virus filtration is a size-based removal step that is most effective when placed late in the process, after impurities that could foul the filter have been reduced. Its role is orthogonal viral clearance, not titer improvement or replacement of inactivation.

Question 35Preparation

A depth filtration train is being designed for harvest clarification. Which factor most strongly influences the filter area required?

  1. The isoelectric point of the product antibody
  2. The solids load in the harvest stream and the target loading capacity per unit area Correct answer.
  3. The number of chromatography cycles planned
  4. The buffer conductivity of the equilibration solution

Explanation

Depth filter sizing is driven by the amount of particulate and colloidal solids that must be captured, expressed as a loading capacity per square meter. Product properties such as pI and buffer conditions affect other steps but do not determine depth filter area.

Question 36Preparation

A tangential flow filtration step is used to concentrate a protein solution. Which observation indicates that membrane fouling is developing during the run?

  1. A stable permeate flux over the entire run
  2. A decline in permeate flux at constant crossflow and a rising transmembrane pressure Correct answer.
  3. An increase in retentate protein concentration as expected
  4. A decrease in the feed tank volume

Explanation

Fouling reduces the effective membrane permeability, which appears as falling flux at constant crossflow or rising transmembrane pressure to maintain flow. Normal concentration and tank volume decreases are expected outcomes, not indicators of fouling.

Question 37Preparation

Which formulation excipient is commonly added to a liquid protein formulation to protect against interfacial stress during freezing and drying?

  1. A surfactant such as polysorbate added at low concentration Correct answer.
  2. A reducing agent such as dithiothreitol
  3. A high concentration of sodium chloride
  4. A chelating agent such as EDTA at high concentration

Explanation

Surfactants such as polysorbate 20 or 80 compete for interfaces and reduce adsorption and aggregation of protein at air-liquid and ice-liquid surfaces. They are used at low concentrations and are not a substitute for buffer or tonicity agents.

Question 38Preparation

A batch record shows that the production bioreactor was held at the target temperature but the pH exceeded the upper control limit for two hours. Which action best follows good manufacturing practice?

  1. Adjust the batch record to show the pH was within limits
  2. Document the excursion as a deviation and assess its impact on product quality and the batch disposition Correct answer.
  3. Discard the batch without any investigation
  4. Repeat the pH measurement until a compliant value is obtained

Explanation

An out-of-limit process parameter must be recorded and investigated as a deviation, with an impact assessment on product quality. Falsifying records or discarding without investigation violates data integrity and quality system expectations.

Question 39Preparation

Which control strategy element provides the strongest assurance that a sterile filtration step consistently removes microorganisms?

  1. A pressure hold test performed at the start of the run only
  2. A visual inspection of the filter housing
  3. A validated filter with defined pore rating, integrity testing before and after use, and a validated microbial retention study Correct answer.
  4. A single post-use bubble point test only

Explanation

Sterile filtration assurance comes from a validated filter with a defined retention rating, supported by pre- and post-use integrity testing and a microbial challenge study. Integrity tests alone confirm filter condition but do not establish retention performance.

Question 40Preparation

During a chromatographic elution, the collected peak is split into fractions. Which approach best determines where to pool fractions for maximum yield at acceptable purity?

  1. Pool all fractions containing any detectable protein
  2. Pool fractions based on the color of the solution
  3. Pool only the single fraction with the highest concentration
  4. Use in-line UV absorbance and conductivity traces together with fraction analytical results to define pooling criteria Correct answer.

Explanation

Pooling decisions combine the in-line UV and conductivity profile with analytical results from fractions, such as purity and aggregate content, against predefined criteria. This balances yield against purity in a reproducible way.

Question 41Preparation

A process uses a low pH hold for viral inactivation. Which parameter must be demonstrated to be within range throughout the hold to claim inactivation credit?

  1. The pH of the pool and the hold duration at the validated temperature Correct answer.
  2. The concentration of antifoam in the bioreactor
  3. The column load challenge
  4. The conductivity of the elution buffer

Explanation

Low pH inactivation credit depends on the pool reaching and maintaining the validated pH for the validated duration at the specified temperature. Conductivity, column load, and antifoam are unrelated to the inactivation claim.

Question 42Preparation

Which analytical method is most appropriate for quantifying host cell protein in an antibody process intermediate?

  1. An enzyme-linked immunosorbent assay using anti-host cell protein antibodies Correct answer.
  2. Ion exchange chromatography with conductivity detection
  3. Size exclusion chromatography with UV detection
  4. A Bradford total protein assay

Explanation

Host cell protein is a complex mixture and is quantified with an immunoassay such as an ELISA that uses antibodies raised against the host cell proteome. Total protein assays cannot distinguish host cell protein from product, and chromatographic methods are not specific enough for this purpose.

Question 43Preparation

A process validation study demonstrates that a chromatography step consistently reduces a specific impurity. What is the key requirement for the validation to support routine operation?

  1. The step must be run at a single fixed scale for all future batches
  2. The step must use the maximum possible flow rate
  3. The step must be performed within defined operating ranges and the results must show consistent performance across validation runs Correct answer.
  4. The impurity must be below the limit of detection in every fraction

Explanation

Validation establishes that the step delivers consistent impurity clearance when operated within its defined ranges. Running at maximum flow or requiring undetectable impurity is not the validation standard; reproducibility within the control space is.

Question 44Preparation

A protein A elution pool is adjusted to a higher pH before the next chromatography step. Which consideration most directly justifies this adjustment?

  1. It eliminates the need for a viral filtration step
  2. It increases the binding capacity of the subsequent column
  3. It converts the product into a different isoform
  4. Product stability may be compromised at low pH, so neutralization limits aggregation and degradation during hold Correct answer.

Explanation

Antibodies can aggregate or degrade when held at the acidic pH used for protein A elution, so the pool is often neutralized promptly to protect product quality. The adjustment is a stability measure, not a capacity enhancement or a viral clearance substitute.

Question 45Preparation

In a design-of-experiments study for a cell culture process, which outcome indicates that two factors interact significantly?

  1. The effect of one factor on the response depends on the level of the other factor Correct answer.
  2. Both factors have large main effects that are independent of each other
  3. The response is constant across all combinations of the factors
  4. Neither factor shows a measurable main effect

Explanation

An interaction means the influence of one factor changes depending on the level of another, so the response surface is not additive. Large independent main effects or a flat response indicate the absence of interaction.

Question 46Preparation

A scale-up team observes that a large bioreactor produces more lactate and lower titer than the small-scale model at matched setpoints. Which explanation is most consistent with this finding?

  1. The large bioreactor has a higher viable cell density by definition
  2. The small-scale model was operated at a lower temperature
  3. Gradients in dissolved oxygen and nutrients at large scale create zones of stress and altered metabolism Correct answer.
  4. The large bioreactor uses a different basal medium lot

Explanation

Large vessels develop concentration gradients in oxygen, pH, and nutrients because mixing times increase, exposing cells to fluctuating conditions that can shift metabolism toward lactate production. This scale-dependent heterogeneity explains the divergence despite matched setpoints.

Question 47Preparation

Which document defines the critical process parameters and their acceptable ranges for a commercial biopharmaceutical batch?

  1. The equipment qualification report
  2. The supplier certificate of analysis
  3. The analytical method validation report
  4. The master production record and associated process description Correct answer.

Explanation

Critical process parameters and their ranges are defined in the process description and master production record that govern batch execution. Qualification reports, method validation reports, and supplier certificates serve different quality functions.

Question 48Preparation

A bioreactor harvest is clarified by centrifugation. Which parameter most directly affects the clarity of the centrate?

  1. The pH of the equilibration buffer used later
  2. The conductivity of the harvest buffer
  3. The concentration of antifoam added during the run
  4. The feed flow rate and the resulting residence time in the bowl Correct answer.

Explanation

Centrifuge performance depends on the residence time and gravitational force experienced by the feed, which are set by flow rate and bowl geometry. Higher feed rates shorten residence time and reduce clarification. Buffer conductivity, antifoam, and equilibration pH do not determine centrate clarity.

Question 49Preparation

Which practice best supports data integrity for an electronic batch record in a bioprocess facility?

  1. Enforcing unique user accounts with audit trails that capture changes and cannot be disabled Correct answer.
  2. Permitting operators to edit completed entries without a reason
  3. Allowing shared login credentials to simplify shift handover
  4. Storing raw data only on local instrument hard drives

Explanation

Data integrity relies on attributable actions, so unique accounts and tamper-evident audit trails are essential. Shared logins, unreasoned edits, and unbacked local storage undermine traceability and are not acceptable.

Question 50Preparation

A process intermediate is held overnight in a tank before the next step. Which study best supports the assigned hold time?

  1. A single measurement at the start of the hold
  2. A review of the tank cleaning records
  3. A calculation based on the tank volume
  4. A hold-time study measuring product quality attributes and microbial status over the proposed duration Correct answer.

Explanation

Hold-time studies must demonstrate that product quality and microbiological attributes remain acceptable throughout the proposed hold. A single time point, a volume calculation, or cleaning records do not establish hold-time suitability.