Assume that you measure the OD of two E. coli cultures: culture A and culture B. The spectrophotometer gives you a reading of 3.1 for culture A and 0.03 for culture B. What would you do to determine the concentration of culture A and B and why

Explanation:

Optical density, measured with a spectrophotometer, can be used to measure the concentration of bacteria in a suspension culture. Generally for bacterial cell culture OD reading at 600nm is measured. TYpically a bacterial cell culture of OD600 of 1.0 gives 8 x 108 cells/ml.

1) For culture A- OD value is 3.1, which represent vary dense E.coli culture, therefore should be diluted to keep the absorbance below 1.0 at 600nm.

For culture B-OD value of 0.03 is, which represent presence of very low aount of bacterial cells in the culture. So culture B further need to grow in specific condiiton to reach the OD value near about 1.0

the answer is "a.) well–developed vascular system."

explanation: