Biotechnology — MCQ Practice Questions & Answers

Question 1

What is the primary limitation of primary cell cultures compared to continuous cell lines?

Accepted Answer

Correct answer: B. They have limited lifespan and gradually lose original characteristics — Primary cells have limited replicative lifespan due to the Hayflick limit and may undergo changes over passages, whereas continuous cell lines can divide indefinitely.

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A. They are more expensive to establish initially

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C. They cannot be used for any research purpose

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D. They grow faster than continuous cell lines

Question 2

A researcher observes that their CHO (Chinese Hamster Ovary) cell culture shows reduced protein production despite maintaining normal cell density. What could be the most likely cause?

Accepted Answer

Correct answer: B. Suboptimal osmolarity or nutrient depletion in the medium — Even at normal density, cells require optimal osmolarity (280-320 mOsm/kg) and adequate nutrients. Nutrient depletion reduces metabolic activity and protein synthesis despite maintained cell count.

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A. Excessive CO₂ concentration above 10%

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C. Temperature too high (above 40°C)

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D. Presence of antibiotics in the medium

Question 3

In the context of vaccine production using cell culture, which cell lines are most commonly used in India?

Accepted Answer

Correct answer: B. Vero cells, CHO cells, and HEK293 cells — Vero (monkey kidney), CHO (hamster ovary), and HEK293 (human embryonic kidney) cells are widely used for vaccine production including COVID-19 and other vaccines in India.

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A. Only bacterial cultures

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C. Fungal cultures exclusively

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D. Plant callus tissues only

Question 4

Which of the following represents the correct sequence in scaling up cell culture from laboratory to industrial bioreactor?

Accepted Answer

Correct answer: A. Flask → 10L bioreactor → 100L bioreactor → 1000L bioreactor — Scale-up follows a logical progression from small (flask) to larger volumes, with each step validated for maintaining cell viability, growth rate, and product quality.

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B. 1000L bioreactor → 100L bioreactor → 10L bioreactor → Flask

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C. 10L bioreactor → Flask → 100L bioreactor → 1000L bioreactor

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D. All scales can be done simultaneously without sequence

Question 5

What is the significance of mycoplasma testing in cell culture quality control for biopharmaceutical production?

Accepted Answer

Correct answer: C. Mycoplasma is a critical contaminant that requires detection by PCR or ELISA to ensure product safety and efficacy — Mycoplasma is an obligatory contaminant in cell cultures that can affect cell behavior and product quality. Detection via PCR, culture, or ELISA is mandatory in biopharmaceutical manufacturing per ICH guidelines.

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A. Mycoplasma detection is optional and rarely performed

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B. Mycoplasma contamination is easily visible under light microscope

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D. Mycoplasma only affects bacterial cultures, not mammalian cells

Question 6

In a perfusion bioreactor system used for continuous cell culture, what is the primary advantage over batch culture?

Accepted Answer

Correct answer: B. It removes waste products and replenishes nutrients continuously, allowing prolonged culture and higher cell densities — Perfusion systems continuously exchange medium, removing metabolic wastes and supplying nutrients, enabling higher cell densities and prolonged culture periods compared to batch systems.

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A. It reduces the need for sterilization

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C. It completely eliminates the need for temperature control

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D. It makes contamination control unnecessary

Question 7

What is the significance of using antifoam agents in large-scale bioreactors?

Accepted Answer

Correct answer: B. To prevent foam formation which can cause cell damage and overflow — Foam formation in bioreactors during aeration can cause cell lysis, loss of surface area, and carryover into exhaust lines. Antifoam agents (silicone-based) prevent this.

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A. To increase cell proliferation rate

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C. To replace the need for proper aeration

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D. To reduce the viscosity of culture medium

Question 8

In the fed-batch culture strategy, the primary advantage over batch culture is:

Accepted Answer

Correct answer: B. Extended culture duration with controlled nutrient feeding maintains high cell viability and productivity — Fed-batch feeding strategies prevent nutrient depletion and byproduct accumulation, extending productive culture phases and improving final product titers compared to batch culture.

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A. Requires no monitoring equipment

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C. Produces higher quality proteins than continuous culture

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D. Eliminates all metabolic byproducts

Biotechnology - MCQ Practice Questions