Question 1

Which of the following best describes the central dogma of genetics?

Accepted Answer

DNA is transcribed into mRNA, which is then translated into proteins.

Question 2

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

Ligase

Question 3

Which of the following statements correctly distinguishes prokaryotic from eukaryotic genetic processes?

Accepted Answer

Prokaryotes have circular chromosomes and transcription and translation are coupled in the cytoplasm.

Question 4

Which of the following is NOT a component of a nucleotide?

Accepted Answer

A carboxyl group

Question 5

A mutation that changes a codon for one amino acid into a stop codon is called:

Accepted Answer

Nonsense mutation

Question 6

Which of the following best describes a plasmid?

Accepted Answer

A small, circular DNA molecule that can carry advantageous genes such as antibiotic resistance

Question 7

What does it mean that DNA replication is 'semiconservative'?

Accepted Answer

Each new DNA molecule consists of one old and one new strand.

Question 8

Which type of RNA carries amino acids to the ribosome during translation?

Accepted Answer

Transfer RNA (tRNA)

Question 9

Which of the following best describes an inducible operon?

Accepted Answer

It is usually off but can be turned on in the presence of a specific substrate.

Question 10

Which of the following is an example of a physical method of microbial control that works by denaturing proteins and disrupting membranes through high temperature and pressure?

Accepted Answer

Autoclaving

Question 11

Why are endospores more difficult to kill than regular bacterial cells?

Accepted Answer

They possess a tough outer coating and are metabolically inactive, making them resistant to heat and chemicals.

Question 12

Which of the following best explains why salt or sugar is used to preserve food?

Accepted Answer

They create a hypertonic environment, drawing water out of microbial cells and inhibiting growth.

Question 13

Which of the following best describes the action of alcohols as chemical antimicrobial agents?

Accepted Answer

They denature proteins and disrupt cytoplasmic membranes, leading to cell death.

Question 14

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

Accepted Answer

The drug targets microbial structures or functions not found in host cells.

Question 15

Why is it more difficult to develop drugs against eukaryotic microbes and viruses compared to bacteria?

Accepted Answer

Eukaryotic microbes and viruses share more similarities with human cells, making selective toxicity harder to achieve.

Question 16

A patient is prescribed a broad-spectrum antibiotic. Which of the following is a potential problem with this approach?

Accepted Answer

It increases the risk of developing antibiotic resistance and can disrupt normal microbiota.

Question 17

Which of the following best describes the function of R plasmids in bacteria?

Accepted Answer

They carry genes that confer resistance to antimicrobial drugs.

Question 18

Which of the following is NOT a mechanism by which bacteria can acquire new genetic material?

Accepted Answer

Translation

Question 19

In the disk-diffusion (Kirby-Bauer) test, what does a large zone of inhibition around an antibiotic disk indicate?

Accepted Answer

The antibiotic is highly effective against the bacteria.

Question 20

A microbiologist is using MacConkey agar to culture bacteria from a patient sample. After incubation, colonies appear pink. What does this indicate?

Accepted Answer

The bacteria are Gram-negative and ferment lactose.

Microbial Genetics, Control, and Antimicrobial Drugs: Study Guide

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