Lesson 6 – Estimation of cell concentration – Direct methods exam

1. How would you set up your cell culture flasks for harvest on Friday,
given the following conditions :
i. You are subculturing the cells today, that is Wednesday
ii. You need minimum 9 million cells for your experiment planned
for Friday
iii. Confluency is reached when there are 2.5 x 106
cells / flask
iv. Doubling time is 24 hours
v. Cell division is efficient if there are cells @ atleast 10% and
maximum @ 80% confluency
vi. Remember to save an aliquot of cells for routing culturing in
the lab
Into how many flasks would you split the cells and at what
concentration?

2. Which of the following is not the method of cell counting?

a) Microscopic method

b) Electrical conductivity method

c) Automatic optical method

d) Electroscopic method

3. When choosing fluorophores for use in flow cytometry experiments,
information on %BLANK% is required

a) The sheath fluid you will be using

b) The granularity of the target cell type

c) The excitation and emission spectra of the fluorophores

d) The lasers and filters available on the flow cytometer

4. Which fluorescent dye gives apple green fluorescence?

a) Rhodamine

b) Fluorescein

c) Carmine

d) DAPI

5. %BLANK% electrode is used alongside the orifice in coulter
counter

a) Metal electrode

b) Platinum electrode

c) Silicon electrode

d) Magnesium electrode

6. DAPI stains %BLANK% of the cultured cells

a) cytoplasm

b) cell membrane

c) nucleus

d) mitochondria

7. If cells derived from transformed cells are counted, nuclear staining
can lead to %BLANK% of cell count

a) overestimation

b) underestimation

c) no change in estimation

d) all of the above

8. Newton’s rings formed while placing cover slip on grid of
hemocytometer is due to

a) Reflection

b) Refraction

c) Interference

d) Diffraction

9. The advantage of using improved Neubauer chambers for cell
counting includes :
i. Aids visual morphology of cells
ii. Gives total count and viable count
iii. Accuracy on par with automated methods

a) i and ii are correct

b) ii and iii are correct

c) i, ii and iii are correct

d) i and iii are correct

10. Cell counters that operate on the principle of conductivity change when
a cell passes through an orifice are known as

11. In flow cytometry side scatter is a measure of %BLANK% .

granularity

12. error occurs when two or more cells or particles are
present in the sensing zone at the same time.

13. stain is used to determine the total cell number of pre
implantation embryos

14. An example of cell count by nucleic acid staining is .

15. is used to sort, size distribute and compensate for
cellular debris

16. Cell counting method applicable for aggregated cells is

17. Estimation of cell concentration is ideally performed during the
phase of the culture

18. Microscopic counting is more accurate than electronic counting

a) True

b) False

19. Compensation is done to ensure that fluorescence from one
channel does not spill over into the other

a) True

b) False

20. Coulter counters provide information on mean cell volume in
addition to cell concentration

a) True

b) False

21.Flow cytometry can be used to measure cell count but not
apoptosis

a) True

b) False

22.Unstained cells growing in cell culture can be visualized by
fluorescence microscopy

a) True

b) False

23. Methylene blue is a fluorochrome used to stain cover slip cultures

a) True

b) False

24. Packed cell volume gives measure of viable cell count only

a) True

b) False

25. Transfection efficiency is measurable by determination of cell
counts with fluorescent tags

a) True

b) False

26. Significance of estimation of cell concentration in cell culture

27. Nuclei counting as a method of cell count

28. Evolution of electronic counters for determination of cell concentration

29. Merits and constraints of manual counting

30. Importance of gates , threshold and compensation in automated
counters

31. You are provided with T25 flask containing vero cells. How would you
proceed to determine cell concentration using improved Neubauer
chamber ?

32. Detail on the principles of various automated methods of cell count
determination, their merits and constraints