Objectives of centrifugation MCQs With Answer for B. Pharm students: Centrifugation is a core laboratory technique used to separate, concentrate, and purify particles, organelles, and macromolecules based on size, shape, and density. This targeted collection of MCQs focuses on the key objectives of centrifugation—pelleting, clarification, fractionation, and density-gradient separations—while covering rotor types, RCF calculations, operational parameters, and safety. Each question reinforces practical understanding for formulation, bioprocessing, and analytical workflows. The content is tailored for B. Pharm students preparing for exams and lab work, emphasizing principles, calculations, and real-world applications. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary objective of centrifugation in pharmaceutical labs?
- To sterilize solutions
- To separate mixture components based on density differences
- To increase solution temperature
- To change chemical composition
Correct Answer: To separate mixture components based on density differences
Q2. Which objective best describes differential centrifugation?
- Separating particles by their isopycnic density
- Sequential separation of components by size and sedimentation rate
- Mixing samples rapidly
- Measuring enzyme activity
Correct Answer: Sequential separation of components by size and sedimentation rate
Q3. In preparative centrifugation, what is a common objective?
- Analyzing sedimentation coefficients
- Purifying and collecting bulk quantities of particles or organelles
- Measuring absorbance of a band
- Visualizing protein bands only
Correct Answer: Purifying and collecting bulk quantities of particles or organelles
Q4. Which centrifugation objective applies to removing cellular debris from fermentation broth?
- Isopycnic separation
- Clarification
- Analytical ultracentrifugation
- Electrophoresis
Correct Answer: Clarification
Q5. What is the main goal of density gradient (isopycnic) centrifugation?
- Pelleting all particles at the bottom
- Separating components until each reaches its buoyant density
- Mixing gradients uniformly
- Heating samples for better separation
Correct Answer: Separating components until each reaches its buoyant density
Q6. Which objective of centrifugation is crucial for serum/plasma preparation?
- Concentration of nucleic acids exclusively
- Separation of cellular components from liquid fraction
- Measuring viscosity changes
- Producing isotonic buffers
Correct Answer: Separation of cellular components from liquid fraction
Q7. Why is temperature control an objective during centrifugation of proteins?
- To accelerate sedimentation
- To maintain protein stability and prevent denaturation
- To increase rotor speed safely
- To reduce sample volume
Correct Answer: To maintain protein stability and prevent denaturation
Q8. What objective does a microcentrifuge commonly serve in a pharmacy lab?
- High-speed analytical sedimentation
- Rapid pelleting of small-volume samples (e.g., microfuge tubes)
- Large-scale cell culture clarification
- Creating density gradients for ultracentrifugation
Correct Answer: Rapid pelleting of small-volume samples (e.g., microfuge tubes)
Q9. The objective of using an ultracentrifuge is primarily to:
- Separate macroscopic solids quickly
- Achieve very high RCF to separate subcellular particles and macromolecules
- Sterilize media at high speeds
- Measure turbidity only
Correct Answer: Achieve very high RCF to separate subcellular particles and macromolecules
Q10. Which objective explains use of swing-bucket rotors?
- To create high shear for cell disruption
- To allow tubes to orient horizontally for better band resolution in gradients
- To cool samples faster
- To increase rotor K-factor
Correct Answer: To allow tubes to orient horizontally for better band resolution in gradients
Q11. What is an important objective when selecting rotor type for a separation?
- Choosing the cheapest rotor regardless of application
- Matching rotor geometry to the separation goal (pelleting vs banding)
- Prioritizing aesthetic design
- Ensuring the rotor is from the same manufacturer only
Correct Answer: Matching rotor geometry to the separation goal (pelleting vs banding)
Q12. One objective of optimizing centrifugation time is to:
- Ensure complete separation without unnecessary sample damage or overheating
- Always maximize run time to be safe
- Prevent tube balancing
- Remove buffers from the sample
Correct Answer: Ensure complete separation without unnecessary sample damage or overheating
Q13. Why is calculation of RCF critical as an objective for experiments?
- RCF influences chemical composition of samples
- RCF determines the actual gravitational force applied and standardizes separation across rotors
- RCF is only useful for marketing centrifuges
- RCF indicates the sample pH
Correct Answer: RCF determines the actual gravitational force applied and standardizes separation across rotors
Q14. Which objective is achieved by controlling acceleration and deceleration profiles?
- Faster overheating
- Preservation of fragile gradients and prevention of resuspension
- Maximizing pellet density unnecessarily
- Changing sample osmolarity
Correct Answer: Preservation of fragile gradients and prevention of resuspension
Q15. The K-factor of a rotor is used to achieve which objective?
- Heating the rotor faster
- Estimating time required to pellet particles and comparing rotor efficiencies
- Measuring buffer conductivity
- Determining tuber cap sealing
Correct Answer: Estimating time required to pellet particles and comparing rotor efficiencies
Q16. For pelleting small organelles, which objective is most relevant?
- Using the highest possible temperature
- Selecting appropriate RCF and time to sediment the target organelle without contaminating contaminants
- Using mechanical shaking instead of centrifugation
- Adding detergents to all samples
Correct Answer: Selecting appropriate RCF and time to sediment the target organelle without contaminating contaminants
Q17. In vaccine production, centrifugation objectives often include:
- Concentrating virus particles and removing cellular debris
- Changing viral genome
- Increasing solvent polarity
- Drying antigen powders
Correct Answer: Concentrating virus particles and removing cellular debris
Q18. What objective does rate-zonal centrifugation serve?
- Separating particles by buoyant density exclusively
- Separating particles based on size and sedimentation rate within a stabilizing gradient
- Autoclaving samples
- Chemical fixation of cells
Correct Answer: Separating particles based on size and sedimentation rate within a stabilizing gradient
Q19. Why is balancing tubes an operational objective before running the centrifuge?
- To improve sample homogeneity chemically
- To prevent rotor damage and vibration that could compromise separation
- To increase viscosity of samples
- To sterilize the sample
Correct Answer: To prevent rotor damage and vibration that could compromise separation
Q20. When preparing to pellet proteins, an objective is to choose conditions that:
- Always use maximum speed for all samples
- Provide sufficient RCF and time while preserving protein structure and activity
- Change protein primary sequence
- Ensure complete dehydration of proteins
Correct Answer: Provide sufficient RCF and time while preserving protein structure and activity
Q21. Which objective is specifically targeted by analytical ultracentrifugation?
- Large-scale purification for manufacturing
- Determining molecular weights, sedimentation coefficients, and interaction parameters
- Heating samples to observe denaturation
- Creating emulsions
Correct Answer: Determining molecular weights, sedimentation coefficients, and interaction parameters
Q22. The objective of choosing an appropriate rotor radius relates to:
- Only aesthetics of the centrifuge
- Influencing RCF for a given RPM and thus affecting sedimentation efficiency
- Changing the chemical properties of the sample
- Adjusting pH automatically
Correct Answer: Influencing RCF for a given RPM and thus affecting sedimentation efficiency
Q23. Why is minimizing shear stress an objective when centrifuging fragile cells?
- To rapidly lyse the cells
- To preserve cell viability and structural integrity for downstream assays
- To increase rotor speed
- To precipitate salts
Correct Answer: To preserve cell viability and structural integrity for downstream assays
Q24. Sedimentation coefficient (Svedberg) measurement by centrifugation primarily aims to:
- Estimate particle color changes
- Characterize particle size and shape in analytical ultracentrifugation
- Concentrate plasma only
- Measure electric charge of proteins
Correct Answer: Characterize particle size and shape in analytical ultracentrifugation
Q25. Which objective is achieved by using density markers during gradient centrifugation?
- To change rotor balance dynamically
- To identify band positions corresponding to known densities for fraction collection
- To increase sample temperature
- To sterilize tubes
Correct Answer: To identify band positions corresponding to known densities for fraction collection
Q26. For separating lipoprotein fractions (HDL, LDL), the centrifugation objective is:
- To digest lipids enzymatically
- To fractionate particles by buoyant density using density gradients
- To determine pH of plasma
- To homogenize serum
Correct Answer: To fractionate particles by buoyant density using density gradients
Q27. What objective is met by decanting supernatant after centrifugation?
- Removing buffer salts only
- Separating and recovering the liquid phase while leaving the pellet intact
- Changing particle buoyant density
- Increasing RCF in the next run
Correct Answer: Separating and recovering the liquid phase while leaving the pellet intact
Q28. Which objective requires knowledge of Stoke’s law in centrifugation planning?
- Estimating radiative heat transfer
- Predicting sedimentation velocity of spherical particles in a viscous medium
- Measuring electrical conductivity
- Determining gravitational constant
Correct Answer: Predicting sedimentation velocity of spherical particles in a viscous medium
Q29. The objective of using sealed rotors in hazardous sample processing is to:
- Increase sedimentation coefficient
- Contain aerosols and protect the operator from biohazards
- Enhance mixing speed
- Reduce required RCF
Correct Answer: Contain aerosols and protect the operator from biohazards
Q30. Why is reproducibility an important objective when designing centrifugation protocols?
- It improves visual appeal of labs
- It ensures consistent recovery, purity, and comparability between experiments
- It allows random variation
- It increases sample heterogeneity intentionally
Correct Answer: It ensures consistent recovery, purity, and comparability between experiments
Q31. Which objective is achieved by removing the brake during gradient centrifugation?
- Faster sample cooling
- Preventing disturbance of gradient layers during deceleration
- Increasing pellet density instantly
- Mixing layers for better homogeneity
Correct Answer: Preventing disturbance of gradient layers during deceleration
Q32. For concentration of plasmid DNA from a culture lysate, the centrifugation objective is:
- Isopycnic separation of proteins only
- Pelleting cell debris and clarifying lysate before DNA precipitation
- Directly sequencing DNA in the rotor
- Heating lysate to denature proteins
Correct Answer: Pelleting cell debris and clarifying lysate before DNA precipitation
Q33. Which objective explains the use of fixed-angle rotors?
- Providing gentle horizontal banding
- Efficient pelleting with shorter sedimentation path and faster run times
- Allowing easy extraction of bands from gradients
- Automatic sample balancing
Correct Answer: Efficient pelleting with shorter sedimentation path and faster run times
Q34. The objective of using preservatives or inhibitors during centrifugation of biological samples is to:
- Alter sedimentation coefficients
- Prevent enzymatic degradation and preserve sample integrity
- Increase sample viscosity dramatically
- Enhance rotor speed
Correct Answer: Prevent enzymatic degradation and preserve sample integrity
Q35. What objective is targeted when selecting buffer density for gradient centrifugation?
- To ensure the gradient is colorless
- To create an appropriate density range that resolves target particles’ buoyant densities
- To sterilize particles
- To change protein tertiary structure
Correct Answer: To create an appropriate density range that resolves target particles’ buoyant densities
Q36. In scale-up for industrial centrifugation, an objective is to:
- Use the same microcentrifuge conditions
- Maintain separation efficiency while increasing throughput and process robustness
- Reduce product purity intentionally
- Increase sample heating to speed up runs
Correct Answer: Maintain separation efficiency while increasing throughput and process robustness
Q37. Which objective is associated with using gradient fractionation after centrifugation?
- Discarding all bands
- Collecting distinct fractions enriched in target particles for downstream use
- Homogenizing sample composition
- Measuring only the supernatant pH
Correct Answer: Collecting distinct fractions enriched in target particles for downstream use
Q38. What objective is achieved by pre-chilling centrifuge rotors and samples?
- Speeding up sedimentation significantly
- Minimizing heat-induced denaturation and maintaining cold-chain integrity
- Increasing chemical reaction rates
- Amplifying nucleic acids
Correct Answer: Minimizing heat-induced denaturation and maintaining cold-chain integrity
Q39. Which objective explains using anti-foam agents in samples prior to centrifugation?
- To increase bubble formation
- To prevent foam that can cause sample loss and interfere with separation
- To enhance pellet compaction
- To change particle density
Correct Answer: To prevent foam that can cause sample loss and interfere with separation
Q40. When pelleting bacterial cells from culture, a typical objective is to:
- Keep cells suspended forever
- Concentrate cells into a compact pellet for resuspension or downstream processing
- Denature all proteins immediately
- Convert bacteria into viral particles
Correct Answer: Concentrate cells into a compact pellet for resuspension or downstream processing
Q41. The objective of performing serial centrifugation steps (low to high speed) is to:
- Maximize heat generation
- Sequentially remove larger components then smaller ones for fractionation
- Constantly mix samples
- Destroy sample integrity
Correct Answer: Sequentially remove larger components then smaller ones for fractionation
Q42. What objective is achieved by using optical detection in analytical centrifugation?
- Measuring temperature only
- Monitoring concentration distribution and sedimentation behavior in real time
- Balancing tubes automatically
- Increasing rotor speed beyond limits
Correct Answer: Monitoring concentration distribution and sedimentation behavior in real time
Q43. An objective when centrifuging emulsions is to:
- Increase emulsion stability artificially
- Separate phases to analyze droplet size and stability properties
- Convert liquids into solids
- Make emulsions more viscous
Correct Answer: Separate phases to analyze droplet size and stability properties
Q44. Why is rotor maintenance an important objective for labs using centrifuges?
- To increase noise only
- To ensure safe operation, reliable performance, and accurate separations
- To alter sample composition
- To avoid any cleaning of tubes
Correct Answer: To ensure safe operation, reliable performance, and accurate separations
Q45. Which objective describes the use of continuous-flow centrifuges in industry?
- Batch-wise manual removal of pellets only
- High-throughput continuous separation of solids from liquids for processing large volumes
- Analytical measurement of tiny samples
- Creating density gradients for ultracentrifugation
Correct Answer: High-throughput continuous separation of solids from liquids for processing large volumes
Q46. The objective of using a sucrose or cesium chloride gradient is to:
- Change sample pH drastically
- Create controlled density environments for precise fractionation of biomolecules
- Increase ionic strength only
- Sterilize samples
Correct Answer: Create controlled density environments for precise fractionation of biomolecules
Q47. Why is sample viscosity an important consideration and objective to control?
- Viscosity has no effect on centrifugation
- High viscosity slows sedimentation, so adjusting it can optimize separation
- Viscosity improves rotor life
- Viscosity determines optical density directly
Correct Answer: High viscosity slows sedimentation, so adjusting it can optimize separation
Q48. An important objective when recovering fragile pellets is to:
- Use vigorous pipetting to resuspend immediately
- Resuspend gently to preserve functionality and prevent aggregation
- Heat pellets to dissolve them
- Discard supernatant without care
Correct Answer: Resuspend gently to preserve functionality and prevent aggregation
Q49. Which objective is achieved by using a zonal rotor?
- Small-volume microfuge processing only
- High-capacity separation and fractionation of particles in a continuous or semi-continuous mode
- Measuring pH gradients directly
- Generating intense shear to lyse cells
Correct Answer: High-capacity separation and fractionation of particles in a continuous or semi-continuous mode
Q50. What objective is central to validating a centrifugation protocol in pharmaceutical QA?
- Making protocols intentionally variable
- Demonstrating consistent performance, recovery, purity, and safety according to specifications
- Reducing documentation
- Speeding runs without data
Correct Answer: Demonstrating consistent performance, recovery, purity, and safety according to specifications
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com