Multiple Choice
You take absorbance readings on a spectrophotometer across a 6-hour culture of
A) Clearly,something is wrong with the spectrophotometer and it isn't measuring the correct values.Perhaps something is on the detector,making it register falsely high absorbance numbers.
B) When we establish a growth curve,we should actually plot the log of the number of viable cells vs.time.However,a spectrophotometer can only measure absorbance.Absorbance is NOT the same as the number of viable cells.Many of the cells in the tube are most likely dead,but the machine can't discriminate between a live cell and a dead one.This keeps the absorbance high even into the death phase.
C) It'll happen-E.coli just grow slowly.We haven't gotten to the end of the stationary phase yet.Be patient!
D) Perhaps there's a big smudge of something on the tube that is blocking some of the light.This would lead to an elevated reading for every timepoint after the smudge was placed on the tube.
E) coli cells growing in tryptic soy broth (TSB) .Your absorbance readings clearly indicate a lag phase,a log phase,and a stationary phase.You come back in and take readings at 8,10,12,14,and 16 hours,but the absorbance number remains the same.Shouldn't it start coming down as the closed batch culture enters death phase? What's the most likely thing that is happening?
Correct Answer:

Verified
Correct Answer:
Verified
Q11: In a rapidly multiplying bacterial population,cell numbers
Q12: A hot tub (approx.104<sup> <span class="ql-formula"
Q13: Late log phase of the bacterial growth
Q14: Mycobacterium leprae is typically found infecting the
Q17: When doing experiments with bacteria,<br>A)it is usually
Q18: Small organic molecules that must be provided
Q19: In the cultivation of microaerophilic and anaerobic
Q20: An organism called Bacillus fastidiosus<br>A)might be expected
Q21: Differential media only allows certain bacteria to
Q23: One would expect most strict anaerobic organisms