Question

Four tubes were placed in a rack. To all four tubes, 9 ml of phage buffer was added. 1 ml of a medium titer phage system was added to the first tube and mixed well. 1 ml of the first tube is transferred to the second tube and again mixed. The transfer of 1 ml from one tube to each subsequent tube continues until 1 ml is discarded from the last tube. What is the dilution of phage lysate in the fourth tube?

Answer 1

The phage lysate in the fourth tube has been diluted to a ratio of 1/10,000 after a series of serial dilutions.

Step-by-step explanation:

The question describes a serial dilution process commonly used in virology to estimate the concentration of viruses in a sample. Starting with 9 ml of phage buffer, a high concentration phage lysate is diluted stepwise. In the first tube, after adding 1 ml of phage lysate to 9 ml of buffer, the dilution is 1/10. Each subsequent transfer involves taking 1 ml from the previous tube and adding it to a new tube containing 9 ml of buffer. Thus, the second tube would have a dilution of 1/100, the third tube 1/1,000, and the fourth tube a dilution of 1/10,000.