Serial Dilution

Question 1

A student used a dilution series to investigate the number of cells present in a liquid culture of bacteria.
Describe how he made a 1 in 10 dilution and then used this to make a 1 in 1000 dilution of the original liquid culture of bacteria

Answer 1

1 add 1 part bacteria culture to 9 parts sterile liquid to make 10 to the -1 dilution
2 mix well
3 repeat using 9 parts fresh sterile liquid and one part of 10 to the -1 and 10 to the -2 dilutions to make a 10 to the -3 dilution