Suppose I put 1 billion bacteria in a 10 ml tube of saline, mix well, and label this tube A. Answer
the following questions:
1. Take 1 ml from tube A and put it in an empty tube B. What is the concentration and number
of bacteria in tube B?
concn of bacteria in tube A = 1,000,000,000 per 10 mL or 1E9/10 = 1E8 = 100,000,000/mL.
That's the concn (if you want it quoted in bacteria/mL) and the number of bacteria is the same since you put 1 mL in
To find the concentration and number of bacteria in tube B, we need to understand the dilution process involved.
Given that you initially have 1 billion bacteria in a 10 ml tube (tube A), the concentration can be calculated by dividing the number of bacteria by the volume of the tube.
1. Concentration in Tube A:
Concentration = Number of bacteria / Volume of tube A
Concentration = 1 billion bacteria / 10 ml
Concentration = 100 million bacteria/ml
So, the initial concentration in tube A is 100 million bacteria per milliliter (100 million bacteria/ml).
Now, let's move on to tube B. You have taken 1 ml from tube A and put it in an empty tube B. We can assume that the distribution of bacteria is uniform, so the concentration in tube B will be the same.
2. Concentration in Tube B:
Since you transferred 1 ml from tube A to tube B, the concentration will remain the same. Therefore, the concentration in tube B is also 100 million bacteria/ml.
Next, we can calculate the number of bacteria in tube B using the concentration and volume of tube B.
Number of bacteria in Tube B = Concentration x Volume of tube B
Number of bacteria in Tube B = 100 million bacteria/ml x 1 ml
Number of bacteria in Tube B = 100 million bacteria
So, the number of bacteria in tube B is 100 million bacteria.
In summary, after transferring 1 ml from tube A to tube B, the concentration of bacteria in tube B remains at 100 million bacteria/ml, and the number of bacteria in tube B is 100 million.