micro- mastering ch. 6

An experiment began with 4 cells and ended with 128 cells. How many generations did the cells go through?

5

Most bacteria grow best at pH

7

Three cells with generation times of 60 minutes are inoculated into a culture medium. How many cells are there after 5 hours?

96

which medium or media would an autotroph grow

A

In the figure, which line best depicts a psychrophile incubated at 0°C?

B

the figure, which line best depicts a facultative anaerobe in the absence of O2?

B

In the figure,which line best depicts an obligate anaerobe in the presence of O2?

C

In the figure, which tube shows the expected growth pattern for a facultative anaerobe?

b

the figure shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which sections of the graph illustrate a logarithmic change in cell numbers?

b and d

Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because

biofilms develop on catheters

The term aerotolerant anaerobe refers to an organism that

does not use oxygen but tolerates it

The data in the table indicate that S. aureus is a(n)

facultative halophile

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?

facultative halophiles

Salts and sugars work to preserve foods by creating a

hypertonic environment

During which growth phase will gram-positive bacteria be most susceptible to penicillin?

log phase

The source of nutrients in nutrient agar is

peptone and beef extract

Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2?

superoxide dismutase

Which of the following is the best definition of generation time?

the length of time needed for a cell to divide

Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient broth. After incubation for 4 hours, you can reasonably expect to have

the same number of cells in both

Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched?

thermophile growth at 37 degrees C

An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

true

Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases.

true

bacterial growth refers to increase in the numbers of cells in a bacterial culture

true

turbidity is an indirect measurement of bacterial growth that can be measured using a spectrotometer

true