Using absorbance readings and a standard curve relating absorbance to cell number, you suspect that a bacterial culture contains 7.4 x 109 CFUs/ml. What dilution of this sample would give you a countable plate?

Five dialysis bags, impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution.  At 10 minute intervals, the bags were weighed and the percent change in mass of each bag was graphed.     Which line represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?   Which line represents the bag with the highest initial concentration of sucrose?   Which line or lines represent bags that contain a solution that is still hypertonic at the end of 60 minutes?   What is the best explanation for the shape of line e. after 50 minutes?

100ml of LB media with 25 μg/ml of Amp and 100 μg/ml of Kan final concentration. You have 100ml of LB provided and Amp and Kan stocks at 100 mg/ml and 50 mg/ml provided. Determine how much of each antibiotic stock solution you need to add to 100ml of LB to reach desired antibiotic concentration.

"If you count 70 colonies from a urine culture obtained using 0.001ml calibrated loop, how many colony forming units (CFU) will be reported?"     70     700     7000     70000     700000

Put the following steps for running a gel in order. first Remove comb and put gel int v [ Choose ] Load samples into gel Let gel solidify for 15-20 minutes Connect electrodes and turn on power to run gel second Pour heated, liquid agarose into gel cartridge Remove comb and put gel into bottom of electrophoresis box Pour buffer into electrophoresis box to cover gel third fourth Pour heated, liquid agarose in v fifth Load samples into gel sixth Connect electrodes and turn v

In performing the Kirby-Bauer procedure in a clinical laboratory setting, why must the agar be a certain depth? Why must the absorbance of the inoculum be standardized?

Assume that you are starting with a sample containing 6 billion active cells. Create a dilution plan to reduce this count to a range of 30-300 colonies on a plate. The powdered sample weighs 500 mg (0.5 g). You can use up to 4 plates – you should plate different dilutions and/or volumes of solution. Start your first dilution by adding 10 mL diluent to 0.5 g powder, which is a 1/20 dilution. Hint: Rearranging the “cfu/ml” formula from our dilutions lab can help you solve this. Choose a target cfu count, and your volume plated should be under 0.5 ml.

You plated 0.1 ml of a sample of kombucha diluted by a factor of 10^-3. It produced 43 colonies. What was the original concentration in the sample? Show your calculations.

How many cells would you be plating if you pipetted 200uL into your dish from a 125 x 104 cells/mL cells suspension?

For the following problem indicate the values for each part of the equation and solve for the unknownvalue:Peter adds 200 μL of bacteria to a tube containing 2 mLs of nutrient broth and then adds 300 μL of acertain disinfectant. The final concentration of the disinfectant in this tube after adding it is 5%.C1=C2=V1=V2=