Quiz 2

What is the main principle of the catalase test?

• Decomposition of glucose by enzymes

• Production of oxygen gas from hydrogen peroxide

• Decomposition of proteins into small peptides

• Conversion of carbohydrates to lactic acid

The reagent used in the catalase test is:

• Sulfuric acid

• Hydrogen peroxide (H₂O₂)

• Eosin methylene blue (EMB)

• Crystal violet

What is a positive result for the catalase test?

• Solution changes color to blue

• No change occurs

• Formation of bubbles or oxygen gas

• White precipitate forms

The catalase test is used to differentiate between:

• Gram-positive and Gram-negative bacteria

• Staphylococcus spp. and Streptococcus spp.

• Escherichia coli and Klebsiella pneumoniae

• Salmonella spp. and Shigella spp.

The media commonly used for the urease test is:

• MacConkey agar

• Urea agar / Christensen’s urea agar

• Nutrient broth

• EMB agar

What is a positive indicator for the urease test?

• Media color changes to pink/purple (alkaline)

• Media color remains yellow

• Gas bubbles are produced

• White precipitate forms at the bottom of the test tube

The urease test can help in the diagnosis of the following bacterial infections, EXCEPT:

• Helicobacter pylori

• Proteus mirabilis

• Klebsiella pneumoniae

• Escherichia coli

The media used in the citrate test is:

• MacConkey agar

• Christensen’s urea agar

• Simmons’ citrate agar

• Triple sugar iron agar

What is a positive indicator for the citrate test?

• Media color changes to bright pink

• Media color changes from green to blue

• Formation of gas bubbles

• Media color remains yellow

In the citrate test, the pH indicator used is:

• Methyl red

• Bromothymol blue

• Phenol red

• Neutral red