Q: Which of the following is a correct equation for the breakdown of hydrogen peroxide by catalase?

$$2\ \mathrm{H}_2\mathrm{O}_2 \xrightarrow{\text{catalase}} 2\ \mathrm{H}_2\mathrm{O} + \mathrm{O}_2$$

Question 1

Which of the following best describes a chemoautotroph?

Accepted Answer

An organism that uses inorganic compounds for energy and CO$$_2 as a $$carbon source

Question 2

A bacterium that can grow in the presence or absence of oxygen, but grows better with oxygen, is classified as which of the following?

Accepted Answer

Facultative anaerobe

Question 3

Which enzyme is responsible for converting superoxide radicals (O$$_2^-) $$into hydrogen peroxide (H$$_2O$_2) in $$aerobic bacteria?

Accepted Answer

Superoxide dismutase

Question 4

Which of the following is a correct equation for the breakdown of hydrogen peroxide by catalase?

Accepted Answer

$$2\ \mathrm{H}_2\mathrm{O}_2 \xrightarrow{	ext{catalase}} 2\ \mathrm{H}_2\mathrm{O} + \mathrm{O}_2$$

Question 5

A patient with a wound infection is found to have bacteria that only grow at the top of a thioglycollate broth tube. Which of the following best describes these bacteria?

Accepted Answer

Obligate aerobes

Question 6

Which of the following environmental factors does NOT directly affect microbial growth?

Accepted Answer

Genetic code

Question 7

Which of the following best explains why salt is used to preserve meat?

Accepted Answer

Salt creates a hypertonic environment, causing plasmolysis in bacteria

Question 8

Which of the following statements about nitrogen fixation is correct?

Accepted Answer

Nitrogen fixation converts N$$_2$$ gas into ammonia (NH$$_3$$), which can be used by some bacteria

Question 9

Which of the following is a trace element required for the function of hemoglobin in red blood cells?

Accepted Answer

Iron

Question 10

A bacterium that grows optimally at 15°C but can also grow at 0°C is classified as a:

Accepted Answer

Psychrophile

Question 11

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 12

Which of the following media would you use to selectively grow Staphylococcus aureus and distinguish it from Staphylococcus epidermidis?

Accepted Answer

Mannitol salt agar (MSA)

Question 13

Which of the following is a correct formula for calculating the number of cells after n generations, starting from a single cell?

Accepted Answer

$$2^n$$

Question 14

Which of the following best describes an obligate parasite?

Accepted Answer

An organism that cannot grow outside of a living host

Question 15

Which of the following is a real-life example of a facultative halophile?

Accepted Answer

Staphylococcus aureus

Question 16

A foodborne outbreak is traced to bacteria that can survive pasteurization but do not grow well at 37°C. Which group do these bacteria most likely belong to?

Accepted Answer

Thermoduric mesophiles

Question 17

Which of the following best explains why fever can help the body fight infection by mesophilic bacteria?

Accepted Answer

Fever raises body temperature above the optimum for mesophilic pathogens, inhibiting their growth

Question 18

Which of the following is a correct description of a biofilm?

Accepted Answer

A mixed community of microbes attached to a surface and each other, often encased in a slime layer

Question 19

Which of the following statements about agar is correct?

Accepted Answer

Agar liquefies at 100°C and solidifies at about 40°C

Question 20

A laboratory is using a reducing medium containing sodium thioglycolate. What is the primary purpose of this medium?

Accepted Answer

To deplete oxygen and create an anaerobic environment for obligate anaerobes

Microbial Growth and Nutrition: Essential Concepts for Microbiology

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