Question 1

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

Accepted Answer

Catabolism is exergonic and breaks down molecules, while anabolism is endergonic and builds molecules.

Question 2

A bacterium is placed in a medium containing glucose and oxygen. Which pathway will most efficiently generate ATP, and what is the final electron acceptor?

Accepted Answer

Aerobic respiration; oxygen is the final electron acceptor.

Question 3

Which equation correctly represents the calculation of bacterial doubling time ($$g) $$given the initial population ($$N_0$$), final population ($$N$$), and elapsed time ($$t$$)?

Accepted Answer

$$g = \frac{t}{\ln(N/N_0$)} $$

Question 4

A bacterial culture is growing in a medium with high salt concentration and low water activity ($$a_w). $$Which group of bacteria is most likely to thrive in this environment?

Accepted Answer

Halophiles

Question 5

Which of the following best explains how enzymes speed up chemical reactions in microbial metabolism?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to proceed faster.

Question 6

A microbiologist is using MacConkey agar to isolate bacteria from a stool sample. Which property of MacConkey agar makes it useful for this purpose?

Accepted Answer

It is a selective and differential medium that inhibits Gram-positive bacteria and distinguishes lactose fermenters.

Question 7

Which of the following is a correct description of the Embden-Meyerhoff pathway in glycolysis?

Accepted Answer

It produces ATP and NADH, and is used by animals, plants, protists, fungi, and many bacteria.

Question 8

A bacterial culture is exposed to moist heat at 121°C in an autoclave. What is the primary mechanism by which this treatment controls microbial growth?

Accepted Answer

Oxidation of cell contents and denaturation of proteins and nucleic acids.

Question 9

Which of the following best describes the action of β-lactam antibiotics such as penicillin?

Accepted Answer

They inhibit cell wall synthesis by deactivating penicillin binding proteins and preventing peptide cross-linking.

Question 10

A patient is infected with a bacterium that is catalase positive. Which of the following best explains the significance of this result?

Accepted Answer

The bacterium can detoxify hydrogen peroxide by converting it to oxygen and water.

Question 11

Which of the following equations represents the relationship between Gibbs free energy change ($$\Delta G) $$and reaction spontaneity in microbial metabolism?

Accepted Answer

$$\Delta G \u003c 0$$ indicates a spontaneous (exergonic) reaction.

Question 12

Which of the following best describes the difference between selective and differential media?

Accepted Answer

Selective media inhibits undesired forms, while differential media distinguishes bacteria based on metabolic products or colony appearance.

Question 13

A microbiologist observes a blood agar plate with clear zones around bacterial colonies. What type of hemolysis is indicated, and what does it mean?

Accepted Answer

Beta hemolysis; complete lysis of blood cells.

Question 14

Which of the following is a plausible reason why broad-spectrum antibiotics are not always the best choice for treating infections?

Accepted Answer

They can disrupt normal flora, leading to secondary infections.

Question 15

A bacterium is classified as a chemoautotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

Energy from chemicals, carbon from CO$$_2.$$

Question 16

Which of the following best describes the mechanism of resistance in methicillin-resistant Staphylococcus aureus (MRSA)?

Accepted Answer

Alteration of penicillin binding proteins, preventing antibiotic binding.

Question 17

A microbiologist uses the Kirby-Bauer disc diffusion method to test antibiotic susceptibility. What does a large zone of inhibition around a disc indicate?

Accepted Answer

The bacterium is susceptible to the antibiotic.

Question 18

Which of the following best explains why obligate anaerobes cannot grow in the presence of oxygen?

Accepted Answer

They lack enzymes to detoxify reactive oxygen species such as peroxides.

Question 19

A bacterial population is measured using turbidimetric methods. Which limitation should be considered when interpreting the results?

Accepted Answer

Turbidimetric methods cannot distinguish between viable and non-viable cells.

Microbial Metabolism, Growth, and Control: Study Notes for Health Sciences

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