6. A culture medium consisting of agar, peptone, and beef extract is a (A) chemically defined medium (B) complex medium (C) selective medium (D) differential medium.

4. Which of the following is an advantage of the standard plate count? (A) can readily count cells that form aggregates (B) determines the number of viable cells (C) can be performed on very dilute samples, such as lake water (D) provides immediate results