Question 1

Which of the following statements correctly describes a key structural difference between DNA and RNA?

Accepted Answer

DNA contains the base thymine, while RNA contains uracil.

Question 2

A scientist discovers a bacterial strain that can survive in the presence of a new antibiotic after being exposed to DNA fragments from a dead, resistant bacterium. Which horizontal gene transfer mechanism is most likely responsible?

Accepted Answer

Transformation

Question 3

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 4

A point mutation changes a codon from $$\mathrm{GAA} to$$ $$\mathrm{GAG}$$, both of which code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 5

Which of the following best explains why extrachromosomal DNA, such as plasmids, is valuable to bacteria?

Accepted Answer

It can provide advantageous traits, such as antibiotic resistance.

Question 6

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to the 3' end?

Accepted Answer

DNA polymerase

Question 7

A hospital is trying to sterilize heat-sensitive medical equipment. Which physical method would be most appropriate?

Accepted Answer

Filtration through a $$0.22\ \mu\mathrm{m}$$ membrane

Question 8

Which of the following best distinguishes genotype from phenotype?

Accepted Answer

Genotype is the sequence of DNA, while phenotype is the observable characteristics.

Question 9

Which of the following is a correct example of complement base pairing in DNA?

Accepted Answer

$$\mathrm{A}$$ pairs with $$\mathrm{T}$$, $$\mathrm{G}$$ pairs with $$\mathrm{C}$$

Question 10

A patient develops a superinfection after broad-spectrum antibiotic therapy. What is the most likely explanation?

Accepted Answer

The antibiotic killed normal microbiota, allowing resistant organisms to proliferate.

Question 11

Which of the following best describes the difference between a broad-spectrum and a narrow-spectrum antibiotic?

Accepted Answer

Broad-spectrum antibiotics are effective against a wide range of bacteria, while narrow-spectrum antibiotics target specific types.

Question 12

Which of the following is the correct order of events in gene expression in a prokaryotic cell?

Accepted Answer

Transcription $$\rightarrow$$ Translation

Question 13

Which scientist is credited with discovering penicillin, the first true antibiotic?

Accepted Answer

Alexander Fleming

Question 14

A chemical agent is tested and found to kill 99.9% of a bacterial population in 10 minutes at $$60^\circ \mathrm{C}. $$What is this measurement called?

Accepted Answer

Thermal death time

Question 15

Which of the following best explains why antibiotic resistance is a growing problem in hospitals?

Accepted Answer

Overuse and misuse of antibiotics select for resistant bacteria.

Question 16

Which mode of action is shared by both antifungal and antibacterial drugs?

Accepted Answer

Disruption of cell membrane function

Question 17

A patient is prescribed a semisynthetic antimicrobial drug. Which statement best describes this type of drug?

Accepted Answer

It is a natural compound modified chemically to improve its properties.

Question 18

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

Accepted Answer

Inhibition of cell wall biosynthesis by blocking peptidoglycan cross-linking

Question 19

A researcher uses UV irradiation to sterilize a surface. What is the primary mode of action of this physical control method?

Accepted Answer

Formation of thymine dimers in DNA

Question 20

Which of the following scenarios best illustrates transduction in bacteria?

Accepted Answer

A bacteriophage transfers DNA from one bacterium to another.

Microbial Genetics, Control of Microbial Growth, and Antimicrobial Drugs: Study Guide

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