Question 1

Which of the following best describes the difference between anabolism and catabolism in microbial metabolism?

Accepted Answer

Anabolism synthesizes complex molecules from simpler ones with energy storage, while catabolism breaks down complex molecules to yield energy.

Question 2

A bacterium is found to use glucose as an energy source and requires organic compounds for its carbon source. Which term best describes this organism?

Accepted Answer

Chemoorganotroph

Question 3

Which of the following is a micronutrient required by microorganisms, and what is its primary function?

Accepted Answer

Iron (Fe); functions as a cofactor in respiration

Question 4

Which of the following best explains why active transport is necessary for microbial cells?

Accepted Answer

It enables cells to accumulate solutes against a concentration gradient, often requiring energy.

Question 5

Which transport system in bacteria involves the chemical modification of the substance being transported, often using phosphoenolpyruvate as an energy source?

Accepted Answer

Group translocation

Question 6

A microbe that uses light as an energy source and carbon dioxide as its carbon source is best classified as a:

Accepted Answer

Photoautotroph

Question 7

Which of the following statements about the free energy change ($$\Delta G) of a $$reaction is correct?

Accepted Answer

A negative $$\Delta G$$ means the reaction will proceed with the release of energy.

Question 8

Given the following free energies of formation: $$G_f^0$(A) = -100 kJ/mol, G$$_$$f^0(B) = -50 kJ/$$mol, $$G_f^0$(C) = -200 kJ/mol, G$$_$$f^0(D) = -80 kJ/$$mol, what is $$\Delta G^0$'$$ for the reaction $$A + B \rightarrow C + D$$?

Accepted Answer

$$\Delta G^0$' = (-200) + (-80) - [(-100) + (-50)] = -130 kJ/$$mol

Question 9

Why is $$\Delta G$$ often a more accurate measure of free energy change in microbial habitats than $$\Delta G^0$'$$?

Accepted Answer

$$\Delta G$$ accounts for actual concentrations of reactants and products, which can differ from standard conditions.

Question 10

Which of the following best describes the role of enzymes in microbial metabolism?

Accepted Answer

Enzymes lower the activation energy, increasing the rate of reactions without being consumed.

Question 11

A bacterium is isolated from a hot spring and is found to oxidize hydrogen sulfide ($$H_2S) $$for energy and uses $$CO_2 as $$its carbon source. Which classification best fits this organism?

Accepted Answer

Chemolithoautotroph

Question 12

Which of the following statements about ABC transport systems is correct?

Accepted Answer

They consist of a substrate-binding protein, a transmembrane transporter, and an ATP-hydrolyzing protein.

Question 13

Which of the following is a real-world example of group translocation in bacteria?

Accepted Answer

Glucose uptake and phosphorylation by the phosphotransferase system in E. coli

Question 14

Which of the following best explains why only exergonic reactions can be used by cells to conserve energy?

Accepted Answer

Exergonic reactions release energy that can be captured and stored by the cell.

Question 15

A mutation in a bacterium prevents the synthesis of a vitamin required as a coenzyme. Which of the following is the most likely consequence?

Accepted Answer

The bacterium will be unable to catalyze certain reactions that require the coenzyme.

Question 16

Which of the following best describes the function of magnesium (Mg) in microbial cells?

Accepted Answer

It stabilizes ribosomes, membranes, and nucleic acids, and is required for the activity of many enzymes.

Question 17

Which of the following statements about the chemical composition of a typical microbial cell is correct?

Accepted Answer

Proteins make up the majority of the cell's dry weight.

Question 18

A researcher is studying a marine microbe that requires sodium (Na) for growth. Which of the following best explains this requirement?

Accepted Answer

Sodium is an essential nutrient for some marine microorganisms, possibly involved in osmoregulation or transport.

Question 19

Which of the following best describes the role of prosthetic groups in enzymes?

Accepted Answer

They bind tightly, often covalently and permanently, to enzymes and participate in catalysis.

Microbial Metabolism: Nutrients, Transport, and Bioenergetics

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