Which growth phase of bacterial culture is characterized by maximum specific growth rate and exponential increase in cell number?
Answer: B
Log phase (logarithmic/exponential phase) is when cells divide at maximum rate with doubling time remaining constant. This is the phase of active cell proliferation.
Q.242Easy
What is the optimal pH range for mammalian cell culture?
Answer: B
Mammalian cells require slightly alkaline to neutral pH (7.2-7.4) for optimal growth. pH is maintained using buffers like bicarbonate or HEPES.
Q.243Easy
Which of the following is NOT a component of basal culture media?
Answer: C
Basal media contain amino acids, vitamins, inorganic salts, and carbohydrates. Monoclonal antibodies are added supplements, not basal media components.
Q.244Easy
In animal cell culture, what is the primary purpose of using serum (typically fetal bovine serum)?
Answer: B
FBS provides essential growth factors, hormones, lipids, and attachment factors necessary for cell growth and proliferation in culture.
Q.245Easy
Which method is most appropriate for counting viable cells in a culture?
Answer: B
Trypan blue exclusion assay distinguishes viable (unstained) from non-viable (blue) cells. Hemocytometer counts total cells, not viable ones specifically.
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Q.246Easy
What is contact inhibition in mammalian cell culture?
Answer: A
Contact inhibition is a property where normal mammalian cells stop dividing when they form a monolayer and make physical contact with adjacent cells.
Q.247Medium
Which bioreactor design is most suitable for large-scale mammalian cell culture in pharmaceutical industries?
Answer: C
Stirred-tank bioreactors with integrated aeration and agitation systems are ideal for industrial-scale mammalian cell culture, offering better control and scalability.
Q.248Medium
In continuous culture systems, the dilution rate (D) is defined as:
Answer: B
Dilution rate (D) = flow rate (F)/culture volume (V). In chemostat culture, growth rate equals dilution rate at steady state.
Q.249Medium
What is the primary disadvantage of using animal serum in cell culture for biopharmaceutical production?
Answer: B
Animal serum is costly, batch-to-batch variability is high, regulatory concerns exist, and it complicates downstream processing. Industries are shifting to serum-free media.
Q.250Medium
Which of the following statements is correct regarding cryopreservation of cell cultures?
Answer: B
DMSO and glycerol are cryoprotectants that prevent ice crystal formation and cell damage. Cells are stored at -196°C in liquid nitrogen. Rapid thawing is recommended.
Q.251Medium
In the context of cell culture, what is meant by 'passage number'?
Answer: A
Passage number indicates how many times cells have been subcultured/transferred. Higher passage numbers may result in senescence and altered cell characteristics.
Q.252Medium
Which gas composition is typically maintained in mammalian cell culture bioreactors?
Answer: B
5% CO2 maintains pH through bicarbonate buffering, 5% O2 provides aerobic respiration, and N2 balances the gas mixture. This mimics physiological conditions.
Q.253Medium
What is the primary application of perfusion culture in modern biopharmaceutical manufacturing?
Answer: B
Perfusion culture continuously removes metabolic waste and supplies fresh medium while retaining cells, resulting in higher cell densities and productivity compared to batch culture.
Q.254Hard
How does dissolved oxygen concentration affect cell culture performance?
Answer: C
While cells need oxygen for respiration, excessive DO can cause oxidative stress. Moderate DO levels (30-50% saturation) optimize growth and reduce lactate accumulation.
Q.255Medium
In Indian biotech industries producing recombinant insulin, which cell line is predominantly used?
Answer: B
While CHO cells are used for complex proteins, E. coli is the primary system for insulin production in Indian industries due to cost-effectiveness and regulatory acceptance. However, CHO is also important for other biologics.
Q.256Hard
What is the significance of glucose/lactate ratio monitoring in cell culture?
Answer: A
The glucose consumption rate and lactate production rate indicate metabolic efficiency. High lactate accumulation suggests metabolic stress and can inhibit cell growth.
Q.257Medium
Which of the following is a characteristic feature of suspension culture compared to adherent culture?
Answer: B
Suspension cultures (used for hybridomas, CHO cells) allow cells to grow freely, achieve higher densities, and scale more easily than adherent cultures which require surface attachment.
Q.258Hard
In the 2024-25 era of cell culture, what emerging trend is being adopted by Indian biotech companies?
Answer: B
Modern Indian biotech (2024-25) is shifting toward single-use bioreactors for flexibility, ACF/serum-free media for safety, and automation for consistency in line with global standards.
Q.259Medium
What is the purpose of using microcarriers in animal cell culture?
Answer: B
Microcarriers (Cytodex, Microcarrier, etc.) provide surface area for anchorage-dependent cells in suspension bioreactors, combining advantages of both culture systems.
Q.260Hard
Which parameter is MOST critical to monitor in a GMP-compliant mammalian cell culture facility?
Answer: B
GMP compliance requires continuous monitoring of critical quality attributes (CQAs): viable cell density, viability percentage, and product titer. Real-time monitoring ensures batch consistency and safety.
