General procedure for establishing cell cultures MCQs With Answer

Introduction

This quiz set covers the general procedures for establishing and maintaining cell cultures, tailored for M.Pharm students studying Modern Bio-Analytical Techniques. It focuses on practical and theoretical aspects such as aseptic technique, media selection, dissociation methods, incubation conditions, subculturing, cryopreservation and contamination control. Questions probe deeper into rationale behind routine steps, critical control points, common problems (e.g., mycoplasma, bacterial contamination) and analytical methods used to monitor culture health and growth. These MCQs are designed to reinforce concepts required for laboratory competence and to prepare students for viva, practical exams, and research-based applications in pharmaceutical cell biology.

Q1. What is the primary reason for using a 0.22 µm membrane filter when preparing tissue culture media?

• To remove endotoxins from the medium
• To sterilize heat-labile solutions by removing bacteria
• To concentrate growth factors in the medium
• To adjust osmolarity of the medium

Correct Answer: To sterilize heat-labile solutions by removing bacteria

Q2. Which incubator condition is most commonly used for mammalian cell cultures grown in bicarbonate-buffered media?

• 37°C with 0% CO2
• 30°C with 10% CO2
• 37°C with 5% CO2
• 25°C with atmospheric CO2

Correct Answer: 37°C with 5% CO2

Q3. What is the main purpose of adding serum (e.g., FBS) to cell culture media?

• To provide antibiotics and fungicides
• To supply undefined growth factors, hormones and attachment factors
• To reduce pH fluctuations by buffering capacity
• To increase osmolarity for suspension cells

Correct Answer: To supply undefined growth factors, hormones and attachment factors

Q4. Which enzyme is most commonly used to detach adherent mammalian cells for passaging?

• DNase I
• Trypsin (often with EDTA)
• Lysozyme
• Proteinase K

Correct Answer: Trypsin (often with EDTA)

Q5. A culture shows no turbidity but has altered growth rates and morphology; which contaminant is most likely?

• Fungal contamination
• Bacterial contamination visible by cloudiness
• Mycoplasma infection
• Yeast overgrowth with turbidity

Correct Answer: Mycoplasma infection

Q6. For long-term storage of cell lines, which cryoprotectant and concentration is standard to prevent ice crystal damage?

• Glycerol at 50%
• DMSO at approximately 10%
• Ethylene glycol at 30%
• Sucrose at 5%

Correct Answer: DMSO at approximately 10%

Q7. Which cabinet type is preferred for routine mammalian cell culture to protect both the cells and the operator?

• Horizontal laminar flow clean bench
• Class II Biological Safety Cabinet (BSC)
• Class III glovebox only
• Fume hood

Correct Answer: Class II Biological Safety Cabinet (BSC)

Q8. What is the recommended approximate rate of cooling when freezing adherent cell suspensions to ensure viability?

• Fast freezing at −80°C immediately without control
• Rapid plunge into liquid nitrogen to −196°C
• Controlled cooling at about −1°C per minute to −80°C then transfer to liquid nitrogen
• Cooling at +1°C per minute to room temperature

Correct Answer: Controlled cooling at about −1°C per minute to −80°C then transfer to liquid nitrogen

Q9. Which method gives a quick estimate of cell viability based on membrane integrity?

• MTT assay
• Trypan blue exclusion with hemocytometer counting
• qPCR for housekeeping genes
• Flow cytometry for cell cycle analysis

Correct Answer: Trypan blue exclusion with hemocytometer counting

Q10. What does “passage number” of a cell line refer to in cell culture practice?

• The number of cells plated per flask
• The number of times cells have been subcultured since primary isolation
• The number of days cells have been in culture
• The number of differentiation steps performed

Correct Answer: The number of times cells have been subcultured since primary isolation

Q11. Why are antibiotics often discouraged as a routine additive in cell culture media?

• They always increase cell proliferation and distort assays
• They can mask low-level contamination and promote resistant strains
• They cause immediate cell lysis in all mammalian cells
• They significantly alter CO2 concentration in incubators

Correct Answer: They can mask low-level contamination and promote resistant strains

Q12. Which assay measures metabolic activity by reduction of a tetrazolium salt to formazan and is widely used to assess cell proliferation?

• Trypan blue exclusion
• MTT (or MTS/ XTT) assay
• Annexin V staining for apoptosis
• Crystal violet staining for DNA

Correct Answer: MTT (or MTS/ XTT) assay

Q13. What characteristic differentiates primary cultures from continuous (immortalized) cell lines?

• Primary cultures are genetically modified to express oncogenes
• Primary cultures have limited lifespan and retain donor-specific properties
• Continuous cell lines cannot adhere to surfaces
• Continuous cell lines must be derived from plant tissues

Correct Answer: Primary cultures have limited lifespan and retain donor-specific properties

Q14. Which method is most sensitive for detecting mycoplasma contamination in cell cultures?

• Visual inspection under light microscope
• PCR-based mycoplasma detection assays
• Routine Gram staining of medium
• Measurement of culture turbidity

Correct Answer: PCR-based mycoplasma detection assays

Q15. When is subculturing (passaging) of an adherent culture typically performed based on confluency to maintain exponential growth?

• At 100% confluency to ensure all cells are confluent
• When culture reaches approximately 70–80% confluency
• Only after cells begin to detach spontaneously
• When cell number is less than 10% of flask capacity

Correct Answer: When culture reaches approximately 70–80% confluency

Q16. What is a growth curve “lag phase” in cell culture growth kinetics?

• The period of maximal exponential cell division
• The initial period after plating when cells adapt and do not divide rapidly
• The plateau when nutrients are exhausted and division stops
• The phase when cells undergo necrosis due to overgrowth

Correct Answer: The initial period after plating when cells adapt and do not divide rapidly

Q17. Which physical property distinguishes anchorage-dependent cells from suspension cells?

• Anchorage-dependent cells do not require nutrients
• Anchorage-dependent cells require a surface to attach for growth
• Suspension cells must be grown on extracellular matrix-coated flasks
• Suspension cells always form monolayers

Correct Answer: Anchorage-dependent cells require a surface to attach for growth

Q18. What is the principal advantage of using serum-free defined media in some cell culture applications?

• It guarantees faster growth than serum-containing media in all cases
• It reduces experimental variability and undefined factors, improving reproducibility
• It entirely eliminates the need for sterile technique
• It increases the risk of mycoplasma contamination

Correct Answer: It reduces experimental variability and undefined factors, improving reproducibility

Q19. Which technique provides an objective, automated count and viability estimate using electrical impedance or fluorescence?

• Manual hemocytometer counting with Trypan blue
• Automated cell counters (e.g., Coulter principle or fluorescence-based systems)
• Visual estimation by eye under an inverted microscope
• Colony counting on agar plates

Correct Answer: Automated cell counters (e.g., Coulter principle or fluorescence-based systems)

Q20. What is a common marker of replicative senescence in cultured primary cells used to assess culture aging?

• Increased telomerase activity
• Beta-galactosidase activity at pH 6 (senescence-associated β-galactosidase)
• Higher proliferation rate and reduced cell size
• Complete resistance to trypsinization

Correct Answer: Beta-galactosidase activity at pH 6 (senescence-associated β-galactosidase)

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