Question 1

Which of the following best describes syntrophy in microbial metabolism?

Accepted Answer

A cooperative interaction where two different microbes work together to carry out a metabolic reaction that neither can accomplish alone.

Question 2

Which process is responsible for the conversion of ammonia ($$NH_3) $$and nitrite ($$NO_2$$^-$$) to dinitrogen gas (N_2$) and water in oxygen-free environments?

Accepted Answer

Anammox (anaerobic ammonia oxidation)

Question 3

During mixed acid fermentation, which of the following acids is NOT typically produced by enteric bacteria such as E. coli?

Accepted Answer

Citric acid

Question 4

Why is denitrification considered harmful to agriculture?

Accepted Answer

It removes fixed nitrogen from the soil, reducing soil fertility.

Question 5

Which of the following is a key difference between fermentation and anaerobic respiration in microorganisms?

Accepted Answer

Fermentation achieves redox balance by forming organic waste products, while anaerobic respiration uses inorganic electron acceptors.

Question 6

Which equation correctly represents the anammox reaction?

Accepted Answer

$$NH_4$$^+ + $$NO_2$$^- \rightarrow $$N_2 + 2H_2O$

Question 7

In the context of microbial metabolism, what is the primary role of secondary fermenters?

Accepted Answer

They use the products of primary fermenters as substrates.

Question 8

Which of the following statements about mixed acid fermentation is TRUE?

Accepted Answer

It is characteristic of enteric bacteria and produces multiple acids.

Question 9

What is the oxidation state of nitrogen in nitrate ($$NO_3$$^-$$)?

Accepted Answer

$$+5$$

Question 10

Which metabolic process is most important for removing fixed nitrogen from sewage during wastewater treatment?

Accepted Answer

Denitrification

Question 11

A researcher observes two microbial species in a bioreactor. Species A ferments glucose to produce hydrogen, which is then consumed by Species B to reduce sulfate. What is this relationship called?

Accepted Answer

Syntrophy

Question 12

Which of the following is NOT a typical electron acceptor in anaerobic respiration?

Accepted Answer

Oxygen ($$O_2)$$

Question 13

Which of the following best explains why lactic acid fermentation is important in food preservation?

Accepted Answer

It lowers the pH, inhibiting the growth of spoilage organisms.

Question 14

In interspecies electron transfer (IET), how are electrons typically transferred between two microbial species?

Accepted Answer

Via direct cell-to-cell contact or through diffusion of electron carriers.

Question 15

Which of the following is a characteristic of obligate fermenters?

Accepted Answer

They rely solely on fermentation for energy production.

Question 16

Which metabolic process is responsible for the production of yogurt, sauerkraut, and kimchi?

Accepted Answer

Lactic acid fermentation

Question 17

A soil sample contains bacteria that reduce nitrate ($$NO_3$$^-$$) to nitrogen gas (N_2$). What is the name of this process?

Accepted Answer

Denitrification

Question 18

Which of the following is a major environmental consequence of denitrification?

Accepted Answer

Release of $$N_2O$$, a potent greenhouse gas.

Question 19

Which of the following statements about primary fermenters is correct?

Accepted Answer

They break down polymers and monomers of carbohydrates, proteins, and fats.

Question 20

Which of the following is a practical application of anammox bacteria in environmental biotechnology?

Accepted Answer

Removal of fixed nitrogen from wastewater in oxygen-free treatment systems.

chapter 14

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