Question 1

Which of the following best describes Fanny Hesse's contribution to microbiology?

Accepted Answer

She introduced agar as a solidifying agent for culture media, enabling the isolation of pure bacterial colonies.

Question 2

A patient is suspected of having a Helicobacter pylori infection. Which test is most commonly used to detect the presence of H. pylori based on its unique metabolic activity?

Accepted Answer

Urease breath test

Question 3

Which of the following best explains why Staphylococcus aureus can grow on human skin?

Accepted Answer

It is a facultative halophile, able to tolerate higher salt concentrations.

Question 4

Which type of media would you use to distinguish between bacteria that can ferment lactose and those that cannot, and which is selective for Gram-negative organisms?

Accepted Answer

MacConkey agar

Question 5

A microbiologist wants to grow fastidious bacteria that require additional nutrients not found in standard media. Which type of media should be used?

Accepted Answer

Enriched media

Question 6

Which organism is most likely to grow throughout a thioglycolate broth tube, showing no preference for oxygen?

Accepted Answer

Aerotolerant anaerobe

Question 7

Listeria monocytogenes is unique among food-borne pathogens because it can:

Accepted Answer

Grow at refrigeration temperatures, increasing risk in cold-stored foods.

Question 8

Which equation best represents the calculation of bacterial population after $$n$$ generations, starting with $$N_0$$ cells?

Accepted Answer

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

Question 9

Which phase of the bacterial growth curve is characterized by active cell division and exponential increase in cell number?

Accepted Answer

Log (exponential) phase

Question 10

A microbiologist is using a chemostat to maintain a continuous culture. What is the primary advantage of this method?

Accepted Answer

It keeps cells in the log phase, allowing for constant growth and metabolite production.

Question 11

Which of the following is a primary metabolite produced during the log phase of bacterial growth?

Accepted Answer

ATP

Question 12

Which method is considered a direct measurement of microbial growth?

Accepted Answer

Plate count

Question 13

A catalase test is performed on two bacterial isolates. One produces bubbles when hydrogen peroxide is added, while the other does not. What does this indicate?

Accepted Answer

The bubble-producing isolate can detoxify reactive oxygen species using catalase.

Question 14

Which of the following best describes binary fission in prokaryotes?

Accepted Answer

A process where a single cell divides into two genetically identical daughter cells.

Question 15

Which organism would most likely be found growing on mannitol salt agar, and why?

Accepted Answer

Staphylococcus aureus, because it is halotolerant and can ferment mannitol.

Question 16

Which environmental factor is most relevant for the growth of Thermus aquaticus, and what is its significance in biotechnology?

Accepted Answer

High temperature; its heat-stable DNA polymerase is used in PCR.

Question 17

Which of the following is NOT a function of growth factors in microbial cultivation?

Accepted Answer

Serving as selective agents to inhibit unwanted microbes.

Question 18

If a bacterial culture starts with 100 cells and has a generation time of 30 minutes, how many cells will be present after 2 hours? (Assume no cell death.)

Accepted Answer

$$N = 100 	imes 2^4$ = 1600$$

Question 19

Which of the following best explains why it is important to know the growth requirements for a specific bacterium?

Accepted Answer

To select appropriate culture conditions and prevent misidentification in clinical and environmental samples.

Microbial Nutrition and Growth: Study Guide and Key Concepts Chapter 6

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