1) if a bacterium can double every 10 minutes, what is its growth rate? a) 4 b)
ID: 164650 • Letter: 1
Question
1) if a bacterium can double every 10 minutes, what is its growth rate?
a) 4 b) 6 doublings/hour c) 32 doublings/hour d) 6
2) if a bacterium doubles every 15 minutes, what is its growth rate?
3) from the data below, give the estimated number of colonies on a pour plate with the diluation factor of 10-7
squares counted: 23,20, 19,17,27
average the squares
multiply the average by 78
a) 8268 colonies
b) .00000008268 colonies
c) 1653.6 colonies
d) 16,540,000,000 colonies
3) you have a sample of bacteria that serial diluation and pour plate procedures were done on. all the plates have too many bacterias to count. you must come up with an answer. whatc can you do?
a) i can use a plate and use a quebec colony counter to estimate the number of colonies.
b) continue to dilute my sample and make more plates
c) i can use the quebec colony counter on each plate, average the estimated number of colonies.
d) I would have to start over.
4) you have taken a sample of bacteria and done a serial dilution and pour plate procedure. the following data was recorded:
Plate 1-10-2- too many to count
plate 2- 10-3-296 colonies
plate 3- 10-448 colonies
plate 4-10-5 colonies
which plate(s) can be used to calculate CFU/mL and which plate(s) can you NOT use to calculate CFU?ML?
5) bacteria X is known to double every 15 minutes. if we start with 10 bacteria X cells, how many will we have at the end of 9 hours?
6) can we use this plate to perform a Standard Plate Count? It has 2500 colonies at the 10-2 dilution
a) no there are too few colonies
b) yes there .0002 CFUs/mL
c) yes because we know how many colonies and the dilution factor
d) no because the dilution factor is too low.
Explanation / Answer
1. doubling time every 10 minutes then it is 6/hour option b
2. it would be 4/hour
3. again after growing over time repeating procedure may end up in wrong answer si in such case colony counter can be sued to count from each duplicate plates and take a average is best option
4. Plate 1-10-2- too many to count
plate 2- 10-3-296 colonies
plate 3- 10-448 colonies
plate 4-10-5 5 colonies
so look here 10-5 has 5 colonies so 10-4 will have close to 50 (given is 48) then 10-3 will have close to 500 (but given 296) so this dilution can not be used and also 10-2 is not clear to count also can not be sued for counting.
5. every hour there is now 4 doubling time so 9 hours it would be 37 times it would reach to
687194767360 number of colonies
6. option 3 , as we know dilution and colony count we can use it to know colonies count
687194767360 number of colonies
6. option 3 , as we know dilution and colony count we can use it to know colonies count
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