Suppose a mistake is made in preparing a batch of MacConkey agar and the starting pH is 7.6 instead of 6.9–7.3. Would that affect the medium’s sensitivity or specificity? Explain your answer. (See pages 8 and 9, "A Word About Experimental Design," for assistance with these terms

Yes it would affect the MacConkey agar's medium specificity and sensitivity.

Explanation:

MacConkey agar is a medium that is used to culture and isolate gram negative, lactose fermenting bacteria, specifically bacteria from the Enterobacteriaceae and Pseudomonas family.

The components of MacConkey Agar are: lactose, gelatin, bile salts, sodium chloride, crystal violet , agar, e.t.c.

The pH of MacConkey agar when preparing it should be around 6.9 to 7.3 because when the bacteria ferment the lactose present in the medium, resulting in a formation of pink colonies, the pH of the medium would be reduced.

If the starting pH of a MacConkey agar is 7.6, the ability of the agar to correctly identify the organisms would be compromised because the pink colonies formation would be delayed. Hence, the specificity and sensitivity of the MacConkey agar medium would be affected.