Question 1

Which metabolic pathway is primarily used by photoautotrophic eukaryotes and carboxysomes of autotrophic bacteria for CO$$_2$$ fixation?

Accepted Answer

Calvin-Benson cycle

Question 2

A bacterium is found growing only at the very top of a thioglycolate broth tube. What is the most likely oxygen relationship of this organism?

Accepted Answer

Obligate aerobe

Question 3

Which of the following elements is a macronutrient required for the stabilization of ribosomes, membranes, and nucleic acids, and is also a cofactor for DNA polymerase?

Accepted Answer

Magnesium (Mg)

Question 4

Which enzyme catalyzes the reaction $$2H_2O_2 \rightarrow 2H_2O + O_2$ to detoxify hydrogen peroxide in aerobic organisms?

Accepted Answer

Catalase

Question 5

A marine bacterium uses a molecule called aquachelin to acquire which essential micronutrient from its environment?

Accepted Answer

Iron

Question 6

Which of the following best describes the function of nitrogenase in nitrogen-fixing microorganisms?

Accepted Answer

It converts atmospheric nitrogen (N$$_2) to $$ammonia (NH$$_3).$$

Question 7

Which trace element is a component of cytochrome c oxidase and some superoxide dismutases, and is essential for respiration in certain bacteria?

Accepted Answer

Copper (Cu)

Question 8

A facultative anaerobe is inoculated into thioglycolate broth. Where would you expect to see the most growth?

Accepted Answer

Mostly at the top, but some growth throughout the tube

Question 9

Which of the following is a growth factor required for one-carbon metabolism and methyl transfers?

Accepted Answer

Folic acid

Question 10

Why is nitrogenase activity often restricted to specialized cells called heterocysts in some cyanobacteria?

Accepted Answer

Nitrogenase is inhibited by oxygen.

Question 11

Which of the following best explains why obligate anaerobes are killed by oxygen?

Accepted Answer

They lack enzymes to detoxify reactive oxygen species.

Question 12

Which metabolic pathway is used by photosynthetic green sulfur bacteria for CO$$_2$$ fixation?

Accepted Answer

Reverse citric acid cycle

Question 13

A laboratory is attempting to culture an obligate anaerobe. Which of the following methods would be most appropriate?

Accepted Answer

Using an anoxic jar with a palladium catalyst

Question 14

Which of the following reactions is catalyzed by superoxide dismutase?

Accepted Answer

$$2O_2^- + 2H^+ \rightarrow H_2O_2 + O_2$

Question 15

Which macronutrient is essential for the formation of endospores due to its role in stabilizing cell walls as a calcium-dipicolinic acid complex?

Accepted Answer

Calcium

Question 16

Which of the following best describes the role of siderophores in bacterial physiology?

Accepted Answer

They bind and transport iron into the cell.

Question 17

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

Accepted Answer

Facultative aerobe

Question 18

Which trace element is a component of the FeMo cofactor in nitrogenase and is essential for nitrogen fixation?

Accepted Answer

Molybdenum (Mo)

Question 19

Which of the following growth factors is a precursor of NAD$$^+$$ and is essential for redox reactions in metabolism?

Accepted Answer

Nicotinic acid (Niacin)

Question 20

A bacterium isolated from marine environments requires sodium for growth and uses Na$$^+-$$powered ATP synthase. Which macronutrient is especially important for this organism?

Accepted Answer

Sodium

Microbial Metabolism and Nutrient Requirements: Structured Study Notes

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