Identification of Bacteria – Section 1

6. The primary stain of Gram’s method is

A. safranin
B. phenolpthalene
C. crystal violet
D. methyl red

Correct Answer: C. crystal violet

7. At what concentration of sulphuric acid, Nocardia resists decolourization?

A. 0.5% sulphuric acid
B. 5% sulphuric acid
C. 10% sulphuric acid
D. 8% sulphuric acid

Correct Answer: A. 0.5% sulphuric acid

8. Which of the following is commonly used as Gram’s decolouriser?

A. Ethyl alcohol
B. Methyl alcohol
C. Acetone
D. A mixture of ethyl alcohol and acetone

Correct Answer: D. A mixture of ethyl alcohol and acetone

9. Production of acetoin can be detected by which of the following tests?

A. Citrate test
B. Voges-Proskauer test
C. Methyl red test
D. Indole test

Correct Answer: B. Voges-Proskauer test

10. The production of sufficient acid by fermentation of glucose leads to decrease in pH such that pH of the medium falls below 4.5. Which of the following test can detect it?

A. Indole test
B. Methyl red test
C. Citrate utilization test
D. Voges-Proskauer test

Correct Answer: B. Methyl red test

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