Question 1

Which enzyme is responsible for converting hydrogen peroxide ($$H_2O_2) $$into water and oxygen in aerobic microbes?

Accepted Answer

Catalase

Question 2

A bacterium isolated from deep lake sediments is found to grow only in the absence of oxygen and dies when exposed to air. Which classification best describes this organism?

Accepted Answer

Obligate anaerobe

Question 3

Which of the following statements about reactive oxygen species (ROS) is CORRECT?

Accepted Answer

ROS can damage proteins and DNA within cells.

Question 4

A microbe that requires an external source of organic carbon, such as sugars or proteins, is classified as a:

Accepted Answer

Heterotroph

Question 5

Which of the following is a micronutrient required by microbes in very small amounts?

Accepted Answer

Iron

Question 6

A scientist wants to test the motility of a bacterial species. Which type of growth medium should be used?

Accepted Answer

Semisolid medium

Question 7

Which of the following best describes the function of selective media?

Accepted Answer

It suppresses the growth of some microbes while allowing others to grow.

Question 8

A sample from a patient’s wound is streaked onto eosin methylene blue (EMB) agar. After incubation, pink colonies are observed. What can be concluded about the bacteria?

Accepted Answer

They are Gram-negative and ferment lactose.

Question 9

Which of the following is TRUE regarding the use of broth media in microbiology?

Accepted Answer

Broth media are used for growing large batches of microbes.

Question 10

A microbe is described as a chemolithoautotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

Uses inorganic chemicals for energy and inorganic carbon for growth

Question 11

Which of the following statements about growth factors is CORRECT?

Accepted Answer

Fastidious microbes require multiple growth factors supplied in the medium.

Question 12

Why are slant media used in microbiology laboratories?

Accepted Answer

To increase the surface area for microbial growth

Question 13

Which of the following best explains why most pathogens are not obligate aerobes?

Accepted Answer

Obligate aerobes cannot survive in low-oxygen environments found in the host.

Question 14

A microbiologist wants to isolate a pure culture from a mixed sample. Which type of medium and technique should be used?

Accepted Answer

Solid medium and streak plate technique

Question 15

Which of the following is a reason why microbes have evolved mechanisms to detoxify reactive oxygen species (ROS)?

Accepted Answer

ROS can cause damage to proteins and nucleic acids.

Question 16

A microbe that can grow in both the presence and absence of oxygen, switching between aerobic respiration and fermentation, is classified as a:

Accepted Answer

Facultative anaerobe

Question 17

Which of the following elements is NOT considered a macronutrient for microbial growth?

Accepted Answer

Iron

Question 18

A scientist is culturing a fastidious microbe. What must be added to the growth medium to ensure its survival?

Accepted Answer

Amino acids, vitamins, and nitrogenous bases

Question 19

Which of the following is TRUE about autotrophs?

Accepted Answer

They use carbon fixation to convert inorganic carbon into organic carbon.

Question 20

A researcher wants to distinguish between microbes based on their ability to ferment a specific sugar. Which type of medium should be used?

Accepted Answer

Differential medium

Microbial Growth, Oxygen Requirements, and Culturing Techniques CHAPTER 7B

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