Question 1

Which enzyme is primarily responsible for synthesizing new DNA strands during DNA replication in prokaryotes?

Accepted Answer

DNA polymerase III

Question 2

A researcher is studying the effect of temperature on the growth rate of a bacterial culture. If the temperature is increased above the bacterium's optimum, what is the most likely outcome and why?

Accepted Answer

Growth rate decreases because enzymes denature at temperatures above optimum.

Question 3

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It regulates the breakdown of lactose in the presence or absence of glucose.

Question 4

During transcription, which enzyme is responsible for synthesizing RNA from a DNA template?

Accepted Answer

RNA polymerase

Question 5

A patient is infected with a bacterium that is resistant to penicillin. Laboratory analysis reveals the presence of a plasmid. What is the most likely role of this plasmid?

Accepted Answer

It carries genes for antibiotic resistance.

Question 6

Which of the following statements about restriction enzymes is correct?

Accepted Answer

They cut DNA at specific nucleotide sequences.

Question 7

A culture of E. coli is growing in a medium with both glucose and lactose. Which sugar will E. coli preferentially metabolize and why?

Accepted Answer

Glucose, because the lac operon is repressed in the presence of glucose.

Question 8

Which of the following best explains why surfactants are effective disinfectants?

Accepted Answer

They disrupt microbial membranes by reducing surface tension.

Question 9

A virus infects a host cell and integrates its genome into the host's DNA, remaining dormant for several generations. What is this type of viral life cycle called?

Accepted Answer

Lysogenic cycle

Question 10

Which of the following is a correct statement about the Polymerase Chain Reaction (PCR)?

Accepted Answer

PCR requires primers, DNA polymerase, nucleotides, and thermal cycling.

Question 11

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

Accepted Answer

Bactericidal drugs kill bacteria, while bacteriostatic drugs inhibit bacterial growth.

Question 12

A bacterial culture is in stationary phase. Which of the following best describes what is happening in the culture?

Accepted Answer

The rate of cell division equals the rate of cell death.

Question 13

Which of the following is a major cause of the spread of antimicrobial resistance among bacteria?

Accepted Answer

Horizontal gene transfer via plasmids

Question 14

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA carries amino acids to the ribosome and matches them to the mRNA codon.

Question 15

A patient is prescribed a beta-lactam antibiotic. Which of the following best explains how this drug inhibits bacterial growth?

Accepted Answer

It inhibits cell wall synthesis by targeting penicillin-binding proteins.

Question 16

Which of the following equations correctly represents the exponential growth of a bacterial population?

Accepted Answer

$N = N_0 	imes 2^n$

Question 17

Which of the following statements about CRISPR-based gene editing is correct?

Accepted Answer

CRISPR uses a protein called Cas9 to introduce double-stranded breaks at specific DNA sequences.

Question 18

A microbiologist is testing the effect of pH on bacterial growth. She finds that growth is optimal at pH 7, but declines at pH 5 and pH 9. What term best describes this bacterium?

Accepted Answer

Neutrophile

Question 19

Which of the following best explains why UV radiation is effective at sterilizing surfaces?

Accepted Answer

It induces the formation of thymine dimers, disrupting DNA replication.

Question 20

Which of the following is a correct statement about the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Comprehensive Study Guide: Microbiology Core Concepts and Applications

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