Cell Cultures and Characteristics Questions and Answers

Q: During the growth of animal cells in culture, it is noticed that the cells do not look very healthy. After an investigation, this is found that there is a lot of lactic acid in the culture fluid. What is probably wrong with this culture?

Correct answer: The cells do not have enough oxygenLactate accumulates when cells fall back on anaerobic glycolysis, and that happens when the oxygen supply is inadequate for oxidative phosphorylation. The lactate then acidifies the medium, which damages the cells further. The remedy is better aeration or a lower cell density.

Q: Which of the following is NOT part of the growth medium for animal culture?

Correct answer: StarchAnimal cell media supply glucose as the carbon source, along with amino acids, vitamins, inorganic salts and serum. Starch is not among them: animal cells have no extracellular amylase and cannot use a polysaccharide, whereas plant and bacterial media may include one.

Q: Which of the following methods is most likely to be quantitative?

Correct answer: Dilution and platingDilution and plating is quantitative: a measured volume of a known dilution is spread, and the colonies counted give the number of viable organisms in the original sample. Gram staining and a wet mount show what the organisms are and whether they move, but count nothing.

Q: Cell size and cell number can be measured using

Correct answer: coulter counterA Coulter counter draws cells through a narrow aperture across which a current flows. Each cell displaces electrolyte and causes a pulse of resistance - the number of pulses gives the count and the size of each pulse gives the cell volume. A haemocytometer counts but does not size.

Q: Which of the following is a characteristic of a normal cell?

Correct answer: Dependent on external growth factorA normal cell is dependent on growth factors supplied from outside, and also anchorage dependent and subject to contact inhibition, dividing a finite number of times. The other three options describe transformed cells, which have escaped all those controls - which is precisely what makes them cancerous.

Q: The growth of animal cells in vitro in a suitable culture medium is called ___________

Correct answer: Animal tissue cultureGrowing animal cells outside the body in a suitable medium is animal tissue (cell) culture. It requires a sterile environment, a medium supplying nutrients and growth factors, and usually a surface for the cells to attach to. Plant tissue culture is the equivalent for plants, and works quite differently because plant cells are totipotent.

Q: In tissue culture system, this is the main effect of cytokinins

Correct answer: adventitious shoot formationCytokinins promote cell division and, in tissue culture, the formation of adventitious shoots from callus. The balance with auxin decides the outcome: a high cytokinin to auxin ratio gives shoots, a high auxin ratio gives roots, and a balance gives undifferentiated callus.

31.

During the growth of animal cells in culture, it is noticed that the cells do not look very healthy. After an investigation, this is found that there is a lot of lactic acid in the culture fluid. What is probably wrong with this culture?

A.Ethyl alcohol is being produced in excess
B.The cells have too much oxygen
C.Glycolysis is being inhibited
D.The cells do not have enough oxygen

Answer: D

Correct answer: The cells do not have enough oxygen

Lactate accumulates when cells fall back on anaerobic glycolysis, and that happens when the oxygen supply is inadequate for oxidative phosphorylation. The lactate then acidifies the medium, which damages the cells further. The remedy is better aeration or a lower cell density.

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32.

Which of the following is NOT part of the growth medium for animal culture?

A.Starch
B.Serum
C.Carbon source
D.Inorganic salts

Answer: A

Correct answer: Starch

Animal cell media supply glucose as the carbon source, along with amino acids, vitamins, inorganic salts and serum. Starch is not among them: animal cells have no extracellular amylase and cannot use a polysaccharide, whereas plant and bacterial media may include one.

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33.

Which of the following methods is most likely to be quantitative?

A.Dilution and plating
B.Gram staining
C.Wet mount
D.None of these

Answer: A

Correct answer: Dilution and plating

Dilution and plating is quantitative: a measured volume of a known dilution is spread, and the colonies counted give the number of viable organisms in the original sample. Gram staining and a wet mount show what the organisms are and whether they move, but count nothing.

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34.

HeLa cells are a cell line.

A.True
B.False

Answer: A

If a homogenous cell culture has the ability to grow indefinitely in vitro, it is termed a cell line. Cell lines would never undergo apoptosis and senescence. HeLa is a cancerous cell line derived from humans and was the first line to be maintained.

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35.

Cell size and cell number can be measured using

A.hemocytometer
B.coulter counter
C.petroff-hausser counting chamber
D.none of these

Answer: B

Correct answer: coulter counter

A Coulter counter draws cells through a narrow aperture across which a current flows. Each cell displaces electrolyte and causes a pulse of resistance - the number of pulses gives the count and the size of each pulse gives the cell volume. A haemocytometer counts but does not size.

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36.

Which of the following is a characteristic of a normal cell?

A.Anchorage independent
B.Continuous cell lines
C.Dependent on external growth factor
D.No contact inhibition

Answer: C

Correct answer: Dependent on external growth factor

A normal cell is dependent on growth factors supplied from outside, and also anchorage dependent and subject to contact inhibition, dividing a finite number of times. The other three options describe transformed cells, which have escaped all those controls - which is precisely what makes them cancerous.

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37.

In animal cell culture, particularly mammalian cell culture, transformation means

A.uptake of new genetic material
B.phenotypic modifications of cells in culture
C.both (1)and (2)
D.release of genetic information

Answer: B

Correct answer: phenotypic modifications of cells in culture

In animal cell culture transformation means a change in the cells’ phenotype - loss of contact inhibition and anchorage dependence, indefinite growth, altered morphology. It is essentially the acquisition of cancer-like properties. The bacterial sense of the word, taking up naked DNA, is quite different.

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38.

What is the effect of excess accumulation of metabolite products (lactate and ammonium) on cells?

A.They act as growth promoters
B.They act as growth inhibitors
C.Have no effect on cells
D.Lactate helps in the growth while ammonium inhibits the growth

Answer: D

Correct answer: Lactate helps in the growth while ammonium inhibits the growth

Ammonium is directly toxic, interfering with intracellular pH and with metabolism, and it inhibits growth at quite low concentrations. Lactate is far better tolerated - at moderate concentrations it can even be used as a substrate - and its harm comes mainly from the acidity it produces rather than from the ion itself.

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39.

The growth of animal cells in vitro in a suitable culture medium is called ___________

A.Gene expression
B.Transgenesis
C.Animal tissue culture
D.Plant tissue culture

Answer: D

Correct answer: Animal tissue culture

Growing animal cells outside the body in a suitable medium is animal tissue (cell) culture. It requires a sterile environment, a medium supplying nutrients and growth factors, and usually a surface for the cells to attach to. Plant tissue culture is the equivalent for plants, and works quite differently because plant cells are totipotent.

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40.

In tissue culture system, this is the main effect of cytokinins

A.shoot elongation
B.adventitious root formation
C.induction of somatic embryos
D.adventitious shoot formation

Answer: D

Correct answer: adventitious shoot formation

Cytokinins promote cell division and, in tissue culture, the formation of adventitious shoots from callus. The balance with auxin decides the outcome: a high cytokinin to auxin ratio gives shoots, a high auxin ratio gives roots, and a balance gives undifferentiated callus.

Discuss in Forum

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