Question

a negative urease test remains yellow or orange in color.
true
false
question 9 (1 point)
bromothymol blue turns blue in alkaline conditions.
true
false
question 10 (1 point)
the reagent used in the catalase test is:
kovacs reagent
barritts a and b
hydrogen peroxide (h₂o₂)
methyl red

Explanation:

• For the urease test: In a negative urease test, the medium remains yellow or orange (as the pH does not increase enough to change the color of the pH - indicator in the medium).
• For bromothymol blue: Bromothymol blue is a pH - indicator. It turns blue in alkaline (basic) conditions (pH > 7.6), green in neutral conditions (pH = 6 - 7.6), and yellow in acidic conditions (pH < 6).
• For the catalase test: The catalase test is used to detect the presence of catalase enzyme. Catalase breaks down hydrogen peroxide (\(H_2O_2\)) into water (\(H_2O\)) and oxygen (\(O_2\)). Kovac's reagent is used in the indole test, Barritt's A and B are used in the Voges - Proskauer test, and methyl red is used in the methyl red test.

Answer:

• For the first question: True
• For the second question: True
• For the third question: Hydrogen peroxide (\(H_2O_2\))