Question 1

Which of the following best explains why bacteria secrete siderophores into their environment?

Accepted Answer

To bind and transport insoluble Fe3+ into the cell for essential metabolic processes

Question 2

A microbiologist wants to study the effect of a single amino acid on E. coli growth. Which type of medium should she use and why?

Accepted Answer

Defined medium, because the exact composition is known and can be manipulated

Question 3

Which of the following is a correct pairing of microbial nutritional classification and its energy and carbon source?

Accepted Answer

Lithoautotroph: energy from inorganic compounds, carbon from CO2

Question 4

Why is the 'Great Plate Count Anomaly' significant in environmental microbiology?

Accepted Answer

It highlights the discrepancy between observed microbial diversity in nature and what can be cultured in the lab

Question 5

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a phosphorylated intermediate

Question 6

A bacterium is classified as an organoheterotroph. Which of the following statements is true?

Accepted Answer

It obtains both energy and carbon from organic compounds

Question 7

Which trace element is most directly involved in electron transport and redox reactions in microbial cells?

Accepted Answer

Iron (Fe)

Question 8

In the electron tower, what does a greater difference in reduction potential ($$\Delta E_0$') $$between electron donor and acceptor indicate?

Accepted Answer

More energy is released during electron transfer

Question 9

Which of the following best explains why some bacteria cannot be cultured in standard laboratory media?

Accepted Answer

They require undefined nutrients or specific growth factors not present in the media

Question 10

A researcher isolates a bacterium that uses $$\mathrm{H_2$} as an $$energy source and $$\mathrm{CO_2$} as a $$carbon source. How should this organism be classified?

Accepted Answer

Lithoautotroph

Question 11

Which of the following equations correctly represents the oxidation of hydrogen gas and the reduction of oxygen during aerobic respiration?

Accepted Answer

$$\mathrm{H_2$ + \frac{1}{2} O_2$ \rightarrow H_2O}$$

Question 12

Which of the following best describes the role of NAD+ in microbial metabolism?

Accepted Answer

It serves as an electron carrier, cycling between oxidized (NAD+) and reduced (NADH) forms

Question 13

Which of the following media would be most appropriate for isolating a fastidious bacterium from a clinical sample?

Accepted Answer

Chocolate agar

Question 14

A bacterium is able to grow on trypticase soy agar but not on a defined minimal medium. What does this suggest about its metabolic capabilities?

Accepted Answer

It is fastidious and requires complex nutrients not present in minimal medium

Question 15

Which of the following statements about the carbon cycle is correct?

Accepted Answer

Heterotrophs use organic carbon for energy and release CO2 as a byproduct

Question 16

Which of the following is a plausible reason why DNA sequencing is used in culture-free studies of microbial diversity?

Accepted Answer

DNA sequencing allows identification of microbes that cannot be grown in the lab

Question 17

Which of the following best describes the process of oxidative phosphorylation?

Accepted Answer

ATP synthesis driven by the flow of protons across a membrane via ATP synthase

Question 18

Which of the following is NOT a macronutrient required by all bacteria?

Accepted Answer

Iron (Fe)

Question 19

A bacterium is found to use polychlorinated biphenyls (PCBs) as a carbon and energy source. Which nutritional classification best fits this organism?

Accepted Answer

Organoheterotroph

Microbial Nutrition and Metabolism: Laboratory Media, Nutrient Acquisition, and Catabolic Diversity

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