Super centrifuge – principle, construction, working, uses, merits, demerits is an essential topic for B. Pharm students studying separation techniques and biopharmaceutical processing. This introduction explains the core principles of centrifugal separation, key construction features (rotors, buckets, vacuum chamber, drive, refrigeration), operational aspects (RCF calculation, rotor types, balancing, temperature control), and practical applications in pharmaceuticals such as cell fractionation, virus purification, and protein isolation. We also cover merits like high resolution and speed, and demerits including cost and sample heating, with safety and maintenance considerations. The content is tailored for exam preparation and practical lab use. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary physical principle behind a super centrifuge?
- Magnetic attraction between particles
- Application of high hydrostatic pressure
- Generation of centrifugal force to accelerate sedimentation
- Chemical precipitation by reagent addition
Correct Answer: Generation of centrifugal force to accelerate sedimentation
Q2. Which formula correctly relates Relative Centrifugal Force (RCF) to rotor radius and speed?
- RCF = 1.118 × 10−5 × r(cm) × rpm
- RCF = 1.118 × 10−5 × r(cm) × (rpm)^2
- RCF = 1.118 × 10−3 × r(m) × (rpm)^2
- RCF = r(cm) / (rpm)^2
Correct Answer: RCF = 1.118 × 10−5 × r(cm) × (rpm)^2
Q3. The sedimentation coefficient is measured in which unit commonly used in centrifugation?
- Newton (N)
- Svedberg (S)
- Pascal (Pa)
- Beckman (B)
Correct Answer: Svedberg (S)
Q4. What is the main purpose of a vacuum chamber in high-speed and ultracentrifuges?
- To maintain sterility of samples
- To reduce air friction and heating at high rotor speeds
- To provide cooling for the rotor
- To increase sample viscosity
Correct Answer: To reduce air friction and heating at high rotor speeds
Q5. Which rotor type is best suited for pelleting small particles quickly?
- Swinging-bucket rotor
- Fixed-angle rotor
- Vertical rotor
- Continuous flow rotor
Correct Answer: Fixed-angle rotor
Q6. Swinging-bucket rotors are particularly advantageous for which application?
- Rapid pelleting of dense organelles
- Isopycnic gradient separation with even band formation
- Analytical sedimentation velocity experiments
- High vacuum operations at >100,000 rpm
Correct Answer: Isopycnic gradient separation with even band formation
Q7. Differential centrifugation is primarily used to separate components based on what?
- Buoyant density only
- Molecular charge alone
- Size and mass (sedimentation rate)
- Optical properties of particles
Correct Answer: Size and mass (sedimentation rate)
Q8. Isopycnic centrifugation separates particles until they reach what condition?
- Maximum sedimentation speed
- Equal buoyant density with the surrounding medium
- Zero rotational velocity
- Complete dehydration
Correct Answer: Equal buoyant density with the surrounding medium
Q9. Which of the following is a common component of ultracentrifuge construction?
- Magnetic stirrer
- Rotor, drive shaft, vacuum chamber, and refrigeration system
- Gas chromatography column
- UV lamp for direct sample illumination
Correct Answer: Rotor, drive shaft, vacuum chamber, and refrigeration system
Q10. Why is refrigeration important in many centrifugation protocols?
- To increase rotor speed
- To prevent thermal denaturation and control sample temperature
- To create a vacuum
- To decrease sample density
Correct Answer: To prevent thermal denaturation and control sample temperature
Q11. What does a lower k-factor of a rotor indicate?
- Slower pelleting time
- Faster pelleting efficiency
- Lower maximum rpm
- Higher sample dilution
Correct Answer: Faster pelleting efficiency
Q12. The analytical ultracentrifuge differs from preparative ultracentrifuge mainly because it:
- Is designed only for clinical samples
- Provides in-situ optical detection for sedimentation analysis
- Operates without a vacuum
- Cannot reach high speeds
Correct Answer: Provides in-situ optical detection for sedimentation analysis
Q13. What is the typical maximum rpm range for small benchtop microcentrifuges used in B.Pharm labs?
- 500–2,000 rpm
- 3,000–5,000 rpm
- 10,000–15,000 rpm
- 50,000–100,000 rpm
Correct Answer: 10,000–15,000 rpm
Q14. Which rotor material is commonly used for high-strength ultracentrifuge rotors?
- Glass
- Aluminum or titanium alloys
- Polypropylene
- Stainless steel only
Correct Answer: Aluminum or titanium alloys
Q15. Which application typically requires an ultracentrifuge rather than a conventional high-speed centrifuge?
- Plasma separation from whole blood for routine labs
- Pelleting of large eukaryotic cells
- Separation of viruses and ribosomal subunits
- Clarification of crude plant extracts
Correct Answer: Separation of viruses and ribosomal subunits
Q16. What safety practice is essential before starting a centrifuge run?
- Ensure tubes are sealed with wax
- Balance rotor tubes by mass and check for cracks
- Leave the lid open for ventilation
- Run at maximum speed briefly to test
Correct Answer: Balance rotor tubes by mass and check for cracks
Q17. Which centrifugation method separates macromolecules by buoyant density in a medium like CsCl?
- Differential centrifugation
- Size exclusion centrifugation
- Isopycnic (equilibrium) centrifugation
- Ultrafiltration centrifugation
Correct Answer: Isopycnic (equilibrium) centrifugation
Q18. What is the consequence of operating a centrifuge with an imbalanced load?
- Improved separation quality
- Increased rotor stability
- Vibration, noise, and potential rotor failure
- Enhanced cooling efficiency
Correct Answer: Vibration, noise, and potential rotor failure
Q19. Which parameter primarily determines the time required to sediment a particle at a fixed RCF?
- Sample color
- Particle sedimentation coefficient and rotor k-factor
- Type of plastic tube used
- Laboratory humidity
Correct Answer: Particle sedimentation coefficient and rotor k-factor
Q20. For gradient ultracentrifugation of proteins, which medium is commonly used to form a density gradient?
- Gelatin
- Cesium chloride, sucrose, or iodixanol
- Polyethylene glycol (PEG) only
- Silica beads
Correct Answer: Cesium chloride, sucrose, or iodixanol
Q21. Which of the following is a major merit of super centrifuges in pharmaceutical research?
- Low capital cost
- Ability to separate subcellular organelles and macromolecules with high resolution
- No requirement for skilled operation
- Negligible maintenance needs
Correct Answer: Ability to separate subcellular organelles and macromolecules with high resolution
Q22. Which is considered a demerit of using ultracentrifugation?
- High throughput for very large volumes
- Low energy consumption
- High initial cost and maintenance, and potential sample heating
- Complete automation with no supervision
Correct Answer: High initial cost and maintenance, and potential sample heating
Q23. What does the term “pellet” refer to in centrifugation?
- The supernatant liquid above the particles
- A compact mass of particles sedimented at the bottom of the tube
- A type of rotor accessory
- A balancing weight
Correct Answer: A compact mass of particles sedimented at the bottom of the tube
Q24. Centrifugal force experienced by a particle increases with which of the following changes?
- Decreasing rotor radius
- Decreasing rpm
- Increasing rpm and increasing radius
- Increasing sample viscosity only
Correct Answer: Increasing rpm and increasing radius
Q25. Which type of centrifugation is best for separating cellular organelles by successively increasing g-forces?
- Differential centrifugation
- Isopycnic centrifugation
- Chromatographic centrifugation
- Electrophoretic centrifugation
Correct Answer: Differential centrifugation
Q26. What role does rotor angle play in particle sedimentation?
- Angle does not affect sedimentation
- Smaller angles favor faster pelleting but produce flattened pellets
- Fixed-angle rotors always produce banded separations like swing buckets
- Larger angles block sedimentation completely
Correct Answer: Smaller angles favor faster pelleting but produce flattened pellets
Q27. Which centrifuge accessory helps protect samples from aerosol contamination during opening?
- Sealed safety buckets and rotors with proper sealing
- Open-top metal tubes
- Non-vented lids with holes
- Glass rotors without lids
Correct Answer: Sealed safety buckets and rotors with proper sealing
Q28. In analytical ultracentrifugation, which detection methods are commonly used?
- Mass spectrometry and NMR only
- Optical absorbance, interference optics, and fluorescence detection
- pH meters
- Infrared spectroscopy exclusively
Correct Answer: Optical absorbance, interference optics, and fluorescence detection
Q29. When purifying viruses from cell lysates, which step often precedes ultracentrifugation?
- Direct high-speed centrifugation without clarification
- Clarification by low-speed centrifugation to remove cell debris
- Lyophilization of the lysate
- Dilution with organic solvents
Correct Answer: Clarification by low-speed centrifugation to remove cell debris
Q30. What is the main maintenance task required to prolong rotor life?
- Daily tuning of rpm above specified limits
- Regular inspection for corrosion, proper cleaning, and adherence to cycle limits
- Soaking in strong acids
- Continuous operation at maximum speed
Correct Answer: Regular inspection for corrosion, proper cleaning, and adherence to cycle limits
Q31. Which factor does NOT directly affect sedimentation rate under centrifugal field?
- Particle size and shape
- Density difference between particle and medium
- Rotor angular velocity (rpm)
- Incubation time at room temperature before loading
Correct Answer: Incubation time at room temperature before loading
Q32. What is the recommended immediate action if excessive vibration occurs when starting a centrifuge?
- Ignore it and increase speed
- Stop the run, open lid, and rebalance tubes after power down
- Seal the lid permanently
- Add more samples to all remaining slots without checking balance
Correct Answer: Stop the run, open lid, and rebalance tubes after power down
Q33. Which of the following biological particles is commonly separated by ultracentrifugation for structural studies?
- Large eukaryotic cells like HeLa at 1,000 g
- Ribosomal subunits and macromolecular complexes
- Small inorganic salts
- Pure water molecules
Correct Answer: Ribosomal subunits and macromolecular complexes
Q34. What advantage do vertical rotors provide in ultracentrifugation?
- They allow very short path lengths and rapid sedimentation for zonal separations
- They prevent all mixing of gradients
- They are ideal for maintaining temperature without refrigeration
- They are only used for low-speed spins
Correct Answer: They allow very short path lengths and rapid sedimentation for zonal separations
Q35. Which is true about the relationship between rpm and RCF?
- RCF increases linearly with rpm
- RCF is independent of rpm
- RCF increases with the square of rpm
- RCF decreases as rpm increases
Correct Answer: RCF increases with the square of rpm
Q36. Which practice helps minimize sample heating during high-speed runs?
- Running at higher rpm than recommended
- Using pre-cooled rotors and refrigerated centrifuge settings
- Leaving lids open during runs
- Add insulating foam around tubes
Correct Answer: Using pre-cooled rotors and refrigerated centrifuge settings
Q37. Which statement correctly describes isopycnic vs differential centrifugation?
- Isopycnic separates by size; differential separates by density
- Isopycnic separates particles to their buoyant densities; differential separates sequentially by size/mass
- Both are identical techniques with different names
- Differential requires cesium chloride gradients only
Correct Answer: Isopycnic separates particles to their buoyant densities; differential separates sequentially by size/mass
Q38. What is a common sign that a rotor should be retired and not used further?
- Manufacturer warranty still valid
- Visible cracks, corrosion pits, or deformation on rotor surface
- Shiny appearance and new labels
- Frequent successful runs without inspections
Correct Answer: Visible cracks, corrosion pits, or deformation on rotor surface
Q39. Which centrifuge type is most suitable for routine blood plasma separation in a hospital lab?
- Analytical ultracentrifuge
- High-speed refrigerated centrifuge (benchtop clinical centrifuge)
- Industrial continuous-flow ultracentrifuge
- Microfluidic chip without spinning
Correct Answer: High-speed refrigerated centrifuge (benchtop clinical centrifuge)
Q40. What is the effect of increasing the density of the medium in a density gradient run?
- Particles float regardless of their density
- Separation resolves based on differing buoyant densities, shifting equilibrium positions
- All particles pellet immediately
- No change in separation behavior
Correct Answer: Separation resolves based on differing buoyant densities, shifting equilibrium positions
Q41. For safe operation, how should tubes be arranged in a fixed-angle rotor?
- All tubes must be randomly placed
- Tubes must be balanced by opposing positions and equal mass
- Only one tube can be used at a time
- Balance is not necessary for fixed-angle rotors
Correct Answer: Tubes must be balanced by opposing positions and equal mass
Q42. Which of the following is NOT a typical application of centrifugation in pharmacy?
- Isolation of plasmid DNA for cloning
- Separation of blood components for diagnostics
- Synthesis of active pharmaceutical ingredients by chemical reaction
- Purification of viral vectors for gene therapy
Correct Answer: Synthesis of active pharmaceutical ingredients by chemical reaction
Q43. What is the recommended cleaning practice for most alloy rotors?
- Use strong acids and abrasives regularly
- Clean with mild detergent, rinse thoroughly, and dry to prevent corrosion
- Immerse in autoclave for sterilization always
- Do not clean rotors ever
Correct Answer: Clean with mild detergent, rinse thoroughly, and dry to prevent corrosion
Q44. Which option best describes a continuous-flow centrifuge used in some industrial processes?
- It processes discrete tubes only
- It allows continuous feeding and collection of separated streams for large-scale operations
- It is used exclusively for analytical sedimentation studies
- It cannot separate liquids from solids
Correct Answer: It allows continuous feeding and collection of separated streams for large-scale operations
Q45. What is the usual effect of increasing viscosity of the medium on sedimentation?
- Faster sedimentation
- No effect at all
- Slower sedimentation due to increased frictional resistance
- Immediate aggregation of particles
Correct Answer: Slower sedimentation due to increased frictional resistance
Q46. Which factor would you adjust to increase RCF without changing rotor radius?
- Decrease run time
- Increase rpm (angular velocity)
- Change tube color
- Replace rotor with one of a larger radius
Correct Answer: Increase rpm (angular velocity)
Q47. Which instrument parameter is most critical for reproducible ultracentrifugation experiments?
- Consistent rotor temperature, speed, and balanced loading
- Tube cap color
- Laboratory room paint color
- Operator shoe size
Correct Answer: Consistent rotor temperature, speed, and balanced loading
Q48. What is the typical operational rpm range for many preparative ultracentrifuges used to separate macromolecules?
- Up to 5,000 rpm
- Approximately 10,000–15,000 rpm
- Often in the range of 30,000–70,000 rpm depending on rotor
- Always above 200,000 rpm
Correct Answer: Often in the range of 30,000–70,000 rpm depending on rotor
Q49. Which precaution reduces the risk of rotor failure due to corrosion?
- Storing rotors wet after cleaning
- Routinely inspecting, drying, and storing rotors according to manufacturer guidelines
- Using hydrochloric acid to clean rotors
- Painting the rotor surface
Correct Answer: Routinely inspecting, drying, and storing rotors according to manufacturer guidelines
Q50. Which technique would you choose to separate nucleic acids based on buoyant density for ultra-pure preparation?
- Differential centrifugation with no gradient
- Isopycnic centrifugation using a cesium chloride gradient
- Gel electrophoresis instead of centrifugation
- Simple filtration through paper
Correct Answer: Isopycnic centrifugation using a cesium chloride gradient
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.
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