Question 1

Which of the following best describes the main difference between chemoautotrophs and chemoheterotrophs?

Accepted Answer

Chemoautotrophs use CO$$_2 as $$their carbon source, while chemoheterotrophs use organic compounds.

Question 2

A hospital patient develops a urinary tract infection after catheterization. This infection is best classified as:

Accepted Answer

A nosocomial (healthcare-associated) infection

Question 3

Which phase of the bacterial growth curve is characterized by a balance between cell division and cell death?

Accepted Answer

Stationary phase

Question 4

Which physical method is most effective for sterilizing heat-sensitive solutions such as certain antibiotics or urea broth?

Accepted Answer

Filtration through a membrane with pores smaller than 0.22 μm

Question 5

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

Their outer membrane acts as a barrier to many antibiotics.

Question 6

A new antibiotic is found to inhibit the 70S ribosome. Which of the following organisms would be most affected?

Accepted Answer

Gram-positive bacteria

Question 7

Which of the following is the correct formula to calculate the number of bacteria after $$n$$ generations, starting from a single cell?

Accepted Answer

$$N = 2^n$$

Question 8

Which of the following statements about the action of chemical microbial control agents is correct?

Accepted Answer

They may damage the plasma membrane, denature proteins, or damage nucleic acids.

Question 9

Which of the following best describes the mechanism of action of quinoline derivatives such as chloroquine against malaria parasites?

Accepted Answer

They bind to DNA and interfere with replication, and produce toxic complexes by binding to ferriprotoporphyrin.

Question 10

Which of the following is a reason why selective toxicity is easier to achieve for antibacterial drugs than for antifungal or antiviral drugs?

Accepted Answer

Bacteria have unique structures such as peptidoglycan cell walls and 70S ribosomes.

Question 11

Which of the following best describes the difference between bacteriostatic and bactericidal antibiotics?

Accepted Answer

Bacteriostatic antibiotics inhibit growth, while bactericidal antibiotics kill bacteria.

Question 12

Which of the following is the best example of a physical method of microbial control used in the food industry to reduce spoilage without sterilization?

Accepted Answer

Pasteurization at 72°C for 15 seconds

Question 13

Which of the following is a plausible reason why the stationary phase occurs in a bacterial growth curve?

Accepted Answer

Nutrients become depleted and waste products accumulate.

Question 14

Which of the following is a correct statement about the use of antibiotic combinations?

Accepted Answer

They can prevent the emergence of resistant microorganisms during therapy.

Question 15

Which of the following is the best definition of the minimum inhibitory concentration (MIC)?

Accepted Answer

The lowest concentration of an antimicrobial that inhibits visible growth of a microorganism.

Question 16

Which of the following is a common method for identifying Haemophilus influenzae in the laboratory?

Accepted Answer

Growth on chocolate agar supplemented with factors V and X

Question 17

Which of the following is a plausible effect of damaging the plasma membrane of a bacterial cell with a chemical agent?

Accepted Answer

The cell will lyse and leak its contents, interfering with microbial growth.

Question 18

Which of the following is a correct statement about the action of penicillin?

Accepted Answer

It inhibits cell wall synthesis by targeting peptidoglycan.

Question 19

Which of the following is a reason why Pseudomonas aeruginosa is a significant concern in healthcare settings?

Accepted Answer

It is an opportunistic pathogen with resistance to many antibiotics.

Microbial Growth & Control of Microbial Growth: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard