Question 1

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

Accepted Answer

Anabolism uses energy to synthesize complex molecules, while catabolism breaks down molecules to release energy.

Question 2

A researcher is testing the effect of temperature on the activity of a bacterial enzyme. Which of the following best explains why enzyme activity decreases sharply above the enzyme's optimal temperature?

Accepted Answer

The enzyme's active site is denatured, altering its three-dimensional structure.

Question 3

Which of the following scenarios best illustrates noncompetitive inhibition of an enzyme?

Accepted Answer

A molecule binds to a site other than the active site, changing the enzyme's shape and reducing activity.

Question 4

During glycolysis, glucose is oxidized to pyruvate. Which of the following best describes the redox reaction occurring in this process?

Accepted Answer

Glucose loses electrons (is oxidized), and NAD$$^+$$ gains electrons (is reduced) to form NADH.

Question 5

Which of the following equations correctly represents substrate-level phosphorylation?

Accepted Answer

$$PEP + ADP \rightarrow Pyruvate + ATP$$

Question 6

A patient’s bacterial infection is being tested for its ability to ferment lactose. Which laboratory method would best help identify the bacteria based on this metabolic property?

Accepted Answer

Use of differential media containing lactose and a pH indicator

Question 7

Which of the following best explains why obligate aerobes require enzymes such as superoxide dismutase and catalase?

Accepted Answer

To detoxify reactive oxygen species like $$O_2$$^-$$ and H_2O_2$

Question 8

A microbiologist is isolating a pure culture from a mixed sample. Which method is most appropriate for obtaining isolated colonies?

Accepted Answer

Streak plate method

Question 9

Which of the following best describes the log (exponential) phase of bacterial growth?

Accepted Answer

Cells are dividing at a constant, maximum rate and generation time is shortest.

Question 10

A hospital is using an autoclave to sterilize surgical instruments. Which of the following conditions is required to achieve sterilization?

Accepted Answer

121$$^\circC$$, 15 psi, 15 minutes

Question 11

Which of the following statements about the disk-diffusion method is correct?

Accepted Answer

It measures the zone of inhibition to assess the effectiveness of antimicrobial agents.

Question 12

Which of the following lists the types of microbes from most resistant to least resistant to chemical methods of microbial control?

Accepted Answer

Prions, Endospores, Mycobacteria, Gram negative, Gram positive, Non-enveloped viruses, Enveloped viruses

Question 13

Which of the following best defines selective toxicity in antimicrobial drugs?

Accepted Answer

The drug targets microbial cells without harming host cells.

Question 14

A patient is prescribed a broad-spectrum antibiotic. Which of the following is a potential risk associated with this treatment?

Accepted Answer

Development of a superinfection due to suppression of normal microbiota.

Question 15

Which of the following best explains why it is difficult to develop drugs with selective toxicity against viruses?

Accepted Answer

Viruses use host cell machinery for replication, making it hard to target them without harming host cells.

Question 16

Which of the following antimicrobial agents inhibits bacterial cell wall synthesis?

Accepted Answer

Penicillin

Question 17

A laboratory is using the broth dilution test to determine the MIC and MBC of an antibiotic. Which of the following best describes how to determine the MBC?

Accepted Answer

The lowest concentration of antibiotic that kills 99.9% of the original inoculum, determined by subculturing broth onto antibiotic-free media.

Question 18

Which of the following mechanisms is NOT a common way bacteria develop resistance to antibiotics?

Accepted Answer

Increased uptake of the drug into the cell

Question 19

Which of the following best describes the action of penicillinase on penicillin?

Accepted Answer

It hydrolyzes the beta-lactam ring, inactivating penicillin.

Question 20

Which of the following is a benefit of using antimicrobial peptides or phage therapy over traditional antibiotics?

Accepted Answer

They can target specific pathogens with reduced impact on normal microbiota.

Microbial Metabolism, Growth, Control, and Antimicrobial Drugs: Study Guide

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