Question 1

Which of the following best describes Medium 1 based on the growth results shown in the table?

Accepted Answer

Both selective and differential

Question 2

Based on the table, which organism is able to grow on Medium 2 but not on Medium 1?

Accepted Answer

Staphylococcus aureus

Question 3

Which line in the growth curve graph best depicts the log phase of a thermophile incubated at room temperature?

Accepted Answer

Line 3

Question 4

A culture medium that allows only Staphylococcus species to grow while distinguishing between S. aureus and S. epidermidis is best described as:

Accepted Answer

Both selective and differential medium

Question 5

If you inoculate 100 facultatively anaerobic cells onto nutrient agar and incubate one plate aerobically and another anaerobically, what result do you expect after 24 hours?

Accepted Answer

More colonies on the aerobic plate

Question 6

Which of the following is a reason why oxygen is toxic to some organisms?

Accepted Answer

Oxygen forms reactive oxygen species that damage cellular components

Question 7

Which of the following equations correctly calculates the number of cells after $$n$$ generations, starting with $$N_0$$ cells and a generation time $$g$$?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 8

Which of the following best explains why salts and sugars are used to preserve foods?

Accepted Answer

They create a hypertonic environment that inhibits microbial growth

Question 9

Which of the following is NOT a property of agar that makes it useful for microbiological media?

Accepted Answer

It is used as a nutrient source by most bacteria

Question 10

A capnophile is an organism that:

Accepted Answer

Requires high concentrations of carbon dioxide

Question 11

Which of the following methods would be best for counting bacteria in a water sample with very low cell density?

Accepted Answer

Filtration

Question 12

Which of the following best describes the stationary phase of a bacterial growth curve?

Accepted Answer

The rate of cell division equals the rate of cell death

Question 13

Which of the following is a source of nitrogen for microbial growth?

Accepted Answer

Amino acids

Question 14

Which of the following best describes the use of buffers in culture media?

Accepted Answer

To neutralize acids produced during growth

Question 15

Which of the following is true about the use of turbidity to estimate bacterial numbers?

Accepted Answer

It provides a relative measure of cell density

Question 16

Which of the following best describes a facultative anaerobe?

Accepted Answer

An organism that uses oxygen but can grow without it

Question 17

Which of the following is a characteristic of biofilms?

Accepted Answer

All of the above

Question 18

Which of the following best describes the generation time of a microorganism?

Accepted Answer

The time required for a cell or population to divide

Question 19

Which of the following temperatures would most likely kill a mesophile?

Accepted Answer

$$60^\circ C$$

Question 20

Which of the following best describes the difference between enrichment, selective, and differential media?

Accepted Answer

Selective media suppress unwanted microbes, differential media distinguish between species, enrichment media enhance growth of desired microbes

Microbiology Study Guide: Media Types, Growth Curves, and Environmental Effects

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