Question 1

Which of the following best describes a chemotroph?

Accepted Answer

An organism that obtains energy from the oxidation of chemical compounds.

Question 2

Cyanobacteria are capable of which type of photosynthesis, and what is a key byproduct?

Accepted Answer

Oxygenic photosynthesis; oxygen

Question 3

A bacterium is found growing in a hot spring at 70°C and a pH of 2. Which term best describes its temperature and pH preferences?

Accepted Answer

Thermophile and acidophile

Question 4

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

Accepted Answer

They lack enzymes such as superoxide dismutase and catalase to detoxify reactive oxygen species.

Question 5

Which phase of the bacterial growth curve is characterized by a balance between cell division and cell death, resulting in no net increase in cell number?

Accepted Answer

Stationary phase

Question 6

A hospital-acquired infection is traced to a biofilm on a catheter. Which property of biofilms most contributes to their resistance to antimicrobial agents?

Accepted Answer

Biofilms provide a physical barrier that limits penetration of antimicrobial agents.

Question 7

Which of the following best defines sterilization?

Accepted Answer

The destruction of all forms of microbial life, including endospores.

Question 8

Which physical method of microbial control works by removing microbes rather than killing them, and is commonly used for heat-sensitive solutions?

Accepted Answer

Filtration

Question 9

Which of the following statements about moist heat sterilization is correct?

Accepted Answer

It kills microorganisms primarily by denaturing proteins and is more effective than dry heat.

Question 10

A disinfectant is tested and found to kill 90% of a bacterial population every 2 minutes. If the initial population is $$1 	imes 10^6$ cells, how many cells remain after 6 minutes?

Accepted Answer

$$1 	imes 10^3$

Question 11

Which chemical disinfectant acts by denaturing proteins and disrupting membranes, and is commonly used as a skin antiseptic?

Accepted Answer

Alcohols

Question 12

Which of the following is a limitation of using ultraviolet (UV) radiation for sterilization?

Accepted Answer

It is only effective on surfaces and transparent fluids.

Question 13

Which of the following best describes the action of sulfonamides?

Accepted Answer

Inhibition of essential metabolite synthesis by acting as competitive inhibitors of PABA in folic acid synthesis

Question 14

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

Accepted Answer

Increased risk of superinfection due to disruption of normal microbiota

Question 15

Which mechanism of bacterial resistance involves the alteration of the drug's target site?

Accepted Answer

Modification of the drug's binding site so the drug can no longer bind effectively

Question 16

Which process is responsible for the transfer of antibiotic resistance genes via a bacteriophage?

Accepted Answer

Transduction

Question 17

Why is selective toxicity more difficult to achieve with antifungal drugs than with antibacterial drugs?

Accepted Answer

Fungi are eukaryotic and share more cellular similarities with human cells.

Question 18

Which of the following is an example of a bacteriostatic drug, and when is its use most appropriate?

Accepted Answer

Tetracycline; when the host immune system can eliminate the pathogen

Question 19

Which of the following best describes the action of ethylene oxide in sterilization?

Accepted Answer

It alkylates proteins and nucleic acids, disrupting their function.

Question 20

A new antiviral drug is designed to inhibit viral reverse transcriptase. Which type of virus would this drug be most effective against?

Accepted Answer

Retroviruses

Microbiology Exam 2 Study Guide: Microbial Metabolism, Growth, Control, and Antimicrobial Drugs

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