Cell Culture Techniques Questions and Answers

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the purpose. Cells drift with passage: they accumulate genetic and epigenetic changes, subpopulations outgrow others, and behaviour shifts. Banking vials at intervals means work can be restarted from a defined early passage rather than continuing with cells that no longer match those used at the beginning, which is what makes results comparable over years.

Answer: B

The first two are standard practice. The third is exactly the attitude that antibiotic use is criticised for encouraging, since a drug controls some organisms rather than preventing contamination. Technique, not chemistry, is what keeps a culture clean.

Answer: C

Short tandem repeat profiling gives a fingerprint that can be matched against reference databases, which is how cross-contamination is detected. Many journals and repositories now require the check. The profile is cheap to obtain and settles the question definitively.

Answer: D

Correct answer: provides an unlimited and consistent supply of cells

An immortalised line divides indefinitely and can be expanded, frozen and shared, so experiments can be repeated by anyone with the same starting material. What is given up is fidelity: immortalisation and long culture change the cells, so they no longer behave exactly like the tissue they came from. That is the trade-off the next item refers to.

Answer: A

Correct answer: True

A primary culture retains the properties of the original tissue but has a limited lifespan, varies between donors and is laborious to obtain. A cell line is unlimited, consistent and convenient but has diverged from the tissue it represents. Neither is better in general - the choice depends on whether the question needs biological fidelity or reproducible quantity.

Answer: B

Specific factors hold the cells in an undifferentiated state, and withdrawing or changing them directs the cells down a chosen path. Getting that balance right is much of the difficulty of the work. Small changes in the medium can send the cells down the wrong path.

Answer: C

Adding or withdrawing particular growth factors directs the cells towards one lineage rather than another. The recipe differs for each target cell type and is often arrived at empirically. Protocols are refined by trial rather than derived from first principles.

Answer: D

Losing a fifth leaves four fifths, which is 800,000. Some loss on thawing is normal, which is why vials are frozen at a higher density than the experiment strictly requires. Counting after thawing rather than before avoids an unpleasant surprise.

Answer: A

A layer of treated cells that cannot themselves divide supplies signals and matrix for the cells of interest. Defined media have replaced them in many applications but not all. Some stem cell work still depends on a feeder layer.

Answer: B

Both are true and the reason gives the necessity: the layer must persist and secrete without competing, so irradiation or a drug is used to stop its division while leaving it metabolically active. The layer supports without competing, which is exactly what is wanted.