Question 1

Which of the following best describes a plasmid in bacterial cells?

Accepted Answer

A small, circular piece of DNA that replicates independently of the chromosome

Question 2

A mutation changes the DNA sequence from $$	ext{TAC} to$$ $$	ext{TAG}$$, resulting in a premature stop codon. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 3

Which mechanism of horizontal gene transfer involves the uptake of naked DNA from the environment?

Accepted Answer

Transformation

Question 4

In the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

The operon is fully activated, leading to transcription of genes for lactose metabolism

Question 5

Which of the following is NOT a possible outcome of a mutation in a bacterial genome?

Accepted Answer

Guaranteed cell death

Question 6

A patient develops an infection after receiving broad-spectrum antibiotics. Which type of infection is most likely?

Accepted Answer

Opportunistic infection

Question 7

Which portal of entry is most frequently used by pathogens causing respiratory diseases?

Accepted Answer

Mucous membranes of the respiratory tract

Question 8

Which statement best differentiates pathogenicity from virulence?

Accepted Answer

Pathogenicity is the ability to cause disease, while virulence is the degree of pathogenicity

Question 9

Which of the following is a characteristic of an AB toxin mechanism?

Accepted Answer

The A subunit is enzymatically active, while the B subunit binds to the host cell

Question 10

Which immune cell is primarily responsible for phagocytosis in the blood?

Accepted Answer

Neutrophil

Question 11

Which of the following best describes the difference between innate and adaptive immunity?

Accepted Answer

Innate immunity is non-specific and present at birth, while adaptive immunity is specific and develops after exposure

Question 12

Which of the following is NOT a way antibodies lead to destruction of pathogens?

Accepted Answer

Direct phagocytosis by antibodies

Question 13

A vaccine that contains inactivated toxins is known as:

Accepted Answer

Toxoid vaccine

Question 14

Which of the following is an example of artificial passive immunity?

Accepted Answer

Receiving antivenom after a snake bite

Question 15

Which of the following is a common myth among vaccine-hesitant individuals?

Accepted Answer

Vaccines cause autism

Question 16

A child presents with a honey-colored crust on the skin. Which bacterium is most likely the causative agent?

Accepted Answer

Staphylococcus aureus

Question 17

Which enzyme produced by bacteria breaks down host tissue and facilitates spread?

Accepted Answer

Hyaluronidase

Question 18

During positive selection of mutants in the lab, which of the following occurs?

Accepted Answer

Only mutants with a desired trait survive under selective conditions

Question 19

Which of the following best describes lysogenic conversion?

Accepted Answer

A bacterium acquires new traits due to integration of a prophage

Question 20

Which formula represents the base pairing rule in DNA?

Accepted Answer

$$	ext{A} = 	ext{T}$$ and $$	ext{G} = 	ext{C}$$

Microbial Genetics, Pathogenicity, Immunity, Vaccines, and Microbial Diseases of the Skin: Study Notes

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