1. Define: selective medium differential medium

2. Why are selective and differential media useful with a polymicrobial specimen, eg, a mixed broth culture?

3. Would most clinical specimens contain only a single type of microorganism or would they be more commonly polymicrobial? 4. Which organism(s) are lactose fermenters?

5. Which organism(s) are non-fermenters?

6. Which organism(s) do not grow on either MacConkey or Columbia CNA medium? Why?

7. A carbohydrate fermentation broth tube which is yellow in color indicates the presence of what

8. What type of substance is in a carbohydrate fermentation broth tube or in a differential agar medium condition? that indicates a certain condition in the media?

9. What is the name of the specific substance which is added to carbohydrate fermentation broth tubes and which turns yellow under acidic conditions

10 What is the function of the small, inverted Durham tube in the larger carbohydrate fermentation broth tube?