Applications of centrifugation MCQs With Answer

Applications of centrifugation MCQs With Answer provide B.Pharm students a focused review of centrifugation principles and pharmaceutical uses. This short, Student-friendly guide covers practical applications — particle separation, clarification, pelleting, density-gradient separation, virus and nanoparticle isolation, formulation development, and analytical ultracentrifugation — and reinforces learning with objective questions. Emphasis is on rotor selection, RCF vs RPM calculations, differential and isopycnic techniques, sample preparation, troubleshooting, and regulatory quality aspects relevant to drug development and quality control. Each MCQ includes answers to build exam readiness for pharmacology, pharmaceutics, and bioprocessing modules. Practice these MCQs to master centrifugation applications in pharmaceutical research. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which of the following best describes the main pharmaceutical application of centrifugation?

• Separation of components based on density and size
• Sterilization of formulations
• pH adjustment of suspensions
• Micronization of powders

Correct Answer: Separation of components based on density and size

Q2. What does RCF stand for in centrifugation?

• Rotational Centrifuge Force
• Relative Centrifugal Force
• Radial Centrifuge Factor
• Relative Centrifuge Frequency

Correct Answer: Relative Centrifugal Force

Q3. Which formula relates RCF, radius (r in cm), and RPM?

• RCF = 1.118 × 10^-5 × r × (RPM)^2
• RCF = 1.118 × 10^-3 × r × (RPM)
• RCF = 1.118 × 10^-5 × (RPM)^2 ÷ r
• RCF = r × RPM ÷ 1.118 × 10^-5

Correct Answer: RCF = 1.118 × 10^-5 × r × (RPM)^2

Q4. Which rotor type is most suitable for layering samples for density-gradient centrifugation?

• Fixed-angle rotor
• Swinging-bucket (swing-out) rotor
• Continuous-flow rotor
• Ultracentrifuge rotor without buckets

Correct Answer: Swinging-bucket (swing-out) rotor

Q5. Differential centrifugation is primarily used to:

• Separate particles by density until they reach equilibrium
• Sequentially pellet components of different sizes by increasing RCF
• Lyse cells chemically
• Measure zeta potential of particles

Correct Answer: Sequentially pellet components of different sizes by increasing RCF

Q6. In isopycnic centrifugation, separation is achieved when particles:

• Reach the bottom of the tube
• Form a pellet regardless of density
• Float at a position matching their buoyant density
• Aggregate due to centrifugal stress

Correct Answer: Float at a position matching their buoyant density

Q7. Which medium is commonly used for density-gradient ultracentrifugation of nucleic acids?

• Sucrose gradient
• Agarose gel
• Cesium chloride (CsCl) gradient
• Polyethylene glycol solution

Correct Answer: Cesium chloride (CsCl) gradient

Q8. Which statement about ultracentrifugation is true?

• It uses low RCF and long times for separation
• It achieves very high RCF, enabling separation of macromolecules and viruses
• It is unsuitable for separating subcellular organelles
• It cannot be temperature-controlled

Correct Answer: It achieves very high RCF, enabling separation of macromolecules and viruses

Q9. The sedimentation coefficient (S) is measured in which unit?

• Newton (N)
• Svedberg (S)
• Pascal (Pa)
• Grams per mole (g/mol)

Correct Answer: Svedberg (S)

Q10. Which factor does NOT directly affect sedimentation rate?

• Particle density
• Medium viscosity
• Temperature of the rotor chamber
• Color of the sample

Correct Answer: Color of the sample

Q11. A fixed-angle rotor is preferred over a swinging-bucket rotor when:

• Delicate layering is required
• Maximum pelleting efficiency and shorter spin times are desired
• Density gradient separation is necessary
• Continuous flow of large volumes is needed

Correct Answer: Maximum pelleting efficiency and shorter spin times are desired

Q12. Which precaution is most important before starting a centrifuge run?

• Ensure rotor temperature is above 40°C
• Balance tubes symmetrically by mass
• Leave tubes open to vent
• Add excess sample to maximize yield

Correct Answer: Balance tubes symmetrically by mass

Q13. Which application uses centrifugation in pharmaceutical quality control?

• Assay of liquid chromatography columns
• Separation of particulates from suspensions for turbidity testing
• Tablet coating thickness measurement
• pH calibration

Correct Answer: Separation of particulates from suspensions for turbidity testing

Q14. What is the main advantage of refrigerated centrifuges in pharmaceutical labs?

• They increase rotor speed beyond ultracentrifuge limits
• They maintain low temperatures to preserve thermolabile samples
• They eliminate the need for balancing
• They allow continuous flow processing

Correct Answer: They maintain low temperatures to preserve thermolabile samples

Q15. Which centrifugation technique is most suitable for isolating exosomes?

• Differential ultracentrifugation with successive spins and washing
• Simple low-speed centrifugation at 500 × g
• Filtration through 0.45 μm filters only
• Gravity sedimentation overnight

Correct Answer: Differential ultracentrifugation with successive spins and washing

Q16. In pharmaceutical nanoparticle separation, increasing viscosity of the medium will:

• Increase sedimentation rate
• Decrease sedimentation rate
• Have no effect on sedimentation
• Cause immediate aggregation

Correct Answer: Decrease sedimentation rate

Q17. Which rotor material is commonly used for high-speed applications due to strength and corrosion resistance?

• Aluminum
• Stainless steel
• Glass
• Polypropylene

Correct Answer: Stainless steel

Q18. What is the purpose of using a cushion (e.g., glycerol or sucrose) under a hollow particle layer?

• To increase the pellet compactness by dehydration
• To protect fragile particles from damage on the tube bottom
• To neutralize pH
• To heat the sample during spin

Correct Answer: To protect fragile particles from damage on the tube bottom

Q19. Which centrifugation mode separates particles by their sedimentation rate without reaching buoyant equilibrium?

• Isopycnic centrifugation
• Rate-zonal (velocity) centrifugation
• Density-gradient equilibrium
• Counterflow centrifugation

Correct Answer: Rate-zonal (velocity) centrifugation

Q20. For pelleting bacteria from culture, a typical laboratory centrifuge run uses approximately which centrifugal range?

• 100–500 × g
• 5000–10,000 × g
• 100,000–200,000 × g
• 0.1–1 × g

Correct Answer: 5000–10,000 × g

Q21. Which of the following is a direct consequence of rotor imbalance during a high-speed run?

• Enhanced separation efficiency
• Excessive vibration and potential damage to rotor and centrifuge
• Reduced sample temperature
• Automatic correction by the centrifuge

Correct Answer: Excessive vibration and potential damage to rotor and centrifuge

Q22. Which parameter is described by the k-factor of a rotor?

• The chemical compatibility of rotor materials
• An indicator of how quickly a rotor will sediment particles (efficiency)
• Maximum allowable RPM only
• Rotor temperature stability

Correct Answer: An indicator of how quickly a rotor will sediment particles (efficiency)

Q23. What is the recommended action if a centrifuge rotor shows signs of corrosion?

• Continue use until failure occurs
• Immediately remove from service and inspect per manufacturer guidance
• Paint over the corroded area
• Increase spin speed to see if corrosion improves

Correct Answer: Immediately remove from service and inspect per manufacturer guidance

Q24. Which centrifugation parameter should be adjusted to reduce overheating of samples?

• Reduce spin time and/or use refrigeration
• Increase RPM to shorten run time
• Remove balance weights
• Use open lids during run

Correct Answer: Reduce spin time and/or use refrigeration

Q25. Which application commonly uses continuous-flow centrifugation in pharmaceutical manufacturing?

• Small-scale analytical separations
• Large-volume clarification of fermentation broths
• DNA agarose gel electrophoresis
• Tablet hardness testing

Correct Answer: Large-volume clarification of fermentation broths

Q26. When resuspending a delicate pellet (e.g., liposomes), the best practice is to:

• Vortex at maximum speed
• Use gentle pipetting and buffer matched to pellet conditions
• Heat to 60°C to dissolve pellet
• Freeze-thaw repeatedly

Correct Answer: Use gentle pipetting and buffer matched to pellet conditions

Q27. Which technique helps improve purity when isolating viruses by centrifugation?

• Simple low-speed pelleting only
• Combining density-gradient ultracentrifugation with prior clarification steps
• Using only room-temperature runs
• Skipping filtration steps

Correct Answer: Combining density-gradient ultracentrifugation with prior clarification steps

Q28. What is the main reason to use sealed tubes in high-speed centrifugation?

• To increase rotor speed beyond rated limits
• To prevent aerosol formation and contain hazardous samples
• To balance tubes automatically
• To promote faster sedimentation

Correct Answer: To prevent aerosol formation and contain hazardous samples

Q29. In protocol optimization, increasing RCF while keeping time constant generally results in:

• Lower sedimentation of particles
• Faster and more complete pelleting of particles
• Complete loss of sample integrity always
• No change in separation

Correct Answer: Faster and more complete pelleting of particles

Q30. Which is true about microcentrifuges commonly used in pharmaceutical labs?

• They typically handle large volumes (>1 L)
• They are used for small volumes (0.2–2 mL) and can reach high RPMs
• They have no speed control
• They are unsuitable for pelleting DNA or proteins

Correct Answer: They are used for small volumes (0.2–2 mL) and can reach high RPMs

Q31. Which problem indicates tubes may have leaked during centrifugation?

• Clear and intact supernatant
• Visible liquid inside the rotor chamber or stains after run
• Expected pellet formation
• Decrease in rotor noise

Correct Answer: Visible liquid inside the rotor chamber or stains after run

Q32. Which density medium is often used for purification of plasmid DNA by ultracentrifugation?

• Cesium chloride (CsCl) gradient
• Polyacrylamide gel
• Sodium chloride solution
• Ethanol

Correct Answer: Cesium chloride (CsCl) gradient

Q33. Which of the following best explains why temperature control is critical for protein centrifugation?

• Proteins are unaffected by heat
• Low temperature prevents denaturation and proteolysis during spin
• High temperature improves sedimentation always
• Temperature only affects rotor life, not samples

Correct Answer: Low temperature prevents denaturation and proteolysis during spin

Q34. Which centrifugation parameter is most important for separating subcellular organelles?

• pH of rotor chamber
• RCF and time sequence (differential centrifugation)
• Color of centrifuge tubes
• Room lighting

Correct Answer: RCF and time sequence (differential centrifugation)

Q35. What is a common indication of over-speeding a rotor beyond its limit?

• Lower RCF achieved
• Loud vibrations and possible catastrophic failure
• Improved sample purity without risk
• Automatic balancing by the device

Correct Answer: Loud vibrations and possible catastrophic failure

Q36. Which centrifuge accessory improves sedimentation for small or dilute particles?

• Higher-volume open beakers
• Using density gradients or concentrating columns (e.g., ultrafiltration)
• Removing refrigeration
• Using unbalanced loads

Correct Answer: Using density gradients or concentrating columns (e.g., ultrafiltration)

Q37. Which centrifugation approach is suitable to clarify cell culture supernatant before downstream chromatography?

• Low to moderate-speed centrifugation followed by microfiltration
• Ultracentrifugation only
• Only chemical precipitation
• Gravity settling overnight as sole step

Correct Answer: Low to moderate-speed centrifugation followed by microfiltration

Q38. Which is NOT a typical safety practice when using centrifuges with biohazardous samples?

• Use sealed rotors or safety caps
• Perform runs with proper decontamination and PPE
• Open rotor immediately after high-speed run without waiting for braking
• Balance tubes and inspect for cracks

Correct Answer: Open rotor immediately after high-speed run without waiting for braking

Q39. The Beckman ultracentrifuge is an example of equipment primarily used for:

• High-speed sedimentation and analytical ultracentrifugation studies
• Low-speed blood separation only
• Tablet compression
• Liquid chromatography

Correct Answer: High-speed sedimentation and analytical ultracentrifugation studies

Q40. When calculating sedimentation time using the rotor k-factor, a lower k-factor means:

• Longer sedimentation time
• Shorter sedimentation time (more efficient rotor)
• No relationship to time
• Rotor cannot be used

Correct Answer: Shorter sedimentation time (more efficient rotor)

Q41. Which centrifuge setting minimizes pellet disruption when braking?

• Maximum braking
• No braking (coast down) or slow/brake-off setting
• Immediate reverse spin
• Removing tubes mid-run

Correct Answer: No braking (coast down) or slow/brake-off setting

Q42. Which application uses centrifugation in formulation development?

• Assessment of suspension stability and sedimentation volume
• Determining melting point of an API
• Measuring tablet disintegration times
• HPLC mobile phase optimization

Correct Answer: Assessment of suspension stability and sedimentation volume

Q43. Which technique aids in separating lipoprotein fractions (HDL, LDL) in clinical labs?

• Size-exclusion chromatography only
• Density-gradient ultracentrifugation
• Electrophoresis without centrifugation
• Simple filtration through 0.22 μm filters

Correct Answer: Density-gradient ultracentrifugation

Q44. Why are polypropylene tubes commonly used in microcentrifuges?

• They are fragile and break easily
• They are chemically resistant and flexible, suitable for high-speed small-volume spins
• They conduct electricity for heating
• They cannot be balanced

Correct Answer: They are chemically resistant and flexible, suitable for high-speed small-volume spins

Q45. Which centrifugation parameter is most critical for isolating membrane vesicles without disrupting them?

• Excessive RCF and very long spin times
• Appropriate RCF and gentle handling to avoid shear and overheating
• Use of metal shavings in tubes
• Frequent freeze-thaw cycles during spin

Correct Answer: Appropriate RCF and gentle handling to avoid shear and overheating

Q46. In a rate-zonal separation, what is important about sample layering onto the gradient?

• The sample must be mixed thoroughly with the gradient
• The sample must be applied as a narrow layer on top to avoid mixing
• The sample should be heated before layering
• Layering is unnecessary for rate-zonal separations

Correct Answer: The sample must be applied as a narrow layer on top to avoid mixing

Q47. Which is an expected outcome of using high-speed centrifugation to clarify protein solutions prior to chromatography?

• Removal of insoluble aggregates and particulates improving column life
• Increased protein aggregation always
• Contamination of chromatography buffers
• Complete denaturation of all proteins

Correct Answer: Removal of insoluble aggregates and particulates improving column life

Q48. Which centrifugation-related calculation would you use to convert RPM to RCF?

• Use the rotor k-factor directly
• Apply RCF = 1.118 × 10^-5 × r × (RPM)^2 where r is radius in cm
• Multiply RPM by 100
• Divide RPM by rotor volume

Correct Answer: Apply RCF = 1.118 × 10^-5 × r × (RPM)^2 where r is radius in cm

Q49. Which centrifugation practice helps in minimizing contamination when handling infectious samples?

• Use of open tubes at high speed
• Use of sealed rotors, biosafety cabinet for sample prep, and proper decontamination
• Skipping PPE to improve dexterity
• Working with aerosols openly

Correct Answer: Use of sealed rotors, biosafety cabinet for sample prep, and proper decontamination

Q50. Which consideration is important when choosing a centrifugal method for purifying therapeutic nanoparticles?

• Particle density, desired purity, scale, rotor type, and gentleness to preserve functionality
• Aesthetic appearance of rotor
• Only the color of the nanoparticles matters
• Ignoring medium viscosity and temperature

Correct Answer: Particle density, desired purity, scale, rotor type, and gentleness to preserve functionality

G S Sachin

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