Question

In nutrient agar, the concentration of agar is:

• A. 1%
• B. 1.5%
• C. 3%
• D. 4%

Hint:

Standard solidifying concentration of agar in routine solid media.

Answer 1

The Correct Option is B

Step 1: Nutrient agar is a general-purpose solid medium used to grow a wide range of non-fastidious bacteria and fungi.

Step 2: It is prepared by adding 1.5% agar to nutrient broth. The agar acts only as a solidifying agent and contributes no nutrients itself.

Step 3: The remaining composition is roughly 0.5% peptone, 0.3% beef or yeast extract and 0.5% sodium chloride in distilled water, with the pH adjusted to about 7.4.

Step 4: Lower amounts such as 1% give a too soft gel and higher amounts like 3% or 4% are unnecessary for routine plates, so 1.5% is correct.