Question

E. coli divides every 20 minutes under optimal conditions. Assuming that meat was contaminated with 10 cells of E.coli, how many cells will be in that meat after 1 hour under optimal conditions?

A. 40

B. 60

C. 160

D. 80.

E. 20

E.coli uses oxygen for its metabolism when oxygen is available, but it can also live in the absence of oxygen. Based on this description, how would you classify E.coli?

A. Microaerophile

B. Facultative aerobe

C. Obligate aerobe

D. Obligate anaerobe

E. Faultative anaerobe

Answer 1

Question 1.) Assuming that each cell divides into two in first generation, 4 in second generation,8 in third generation and soon. Therefore, we get 1x2=2, 2x2=4, 4x2=8. So for 10 cells at division time 20 mins we will get 10x2=20, 20x2=40, 40x2=80. In one hour each cell divides into 8 cells, so 10 cells will divide into 80 cells.

Answer is D.) 80

Question 2.) Answer is E.) Facultative anaerobe, this type of microorganisms by aerobic respiration makes atp when oxygen is present and switches to fermentation when oxygen is absent (e.g E.coli, Staph. Aureus) etc. They are capable of surviving in both the environment.

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