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Dmitry_Shevchenko [17]
2 years ago
7

You dilute an unknown sample of bacteria to 1 x 10-6 and plate out 10 onto a Petri dish. The next day you count 64 colonies. The

number of viable bacteria in the original sample was:___________. a. 6.4x105 cells/ul b. 6.4x 106 cells/ul c. 6.4 x 107 cells/ul d. 6.4 x 108 cells/ul
Biology
1 answer:
Sveta_85 [38]2 years ago
3 0

Answer:

b

Explanation:

The correct answer would be 6.4 x 10^6 cells/ul.

For 1 x 10-6 dilution, the plating factor is 10^6. To find the number of bacteria in the original sample, the plating factor is multiplied by the colony count per ul.

<em>Number of viable bacteria = plating factor x colony count/ul</em>

Since 10 ul gives 64 colonies.  1 ul will give:

         64/10 = 6.4 colonies.

Therefore, the viable bacteria in the original sample = 6.4 x 10^6 cells/ul

The correct option is b.

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