Question 1

Which of the following best describes the term 'pathogenicity' in microbiology?

Accepted Answer

The ability of a microbe to cause disease in a host.

Question 2

A patient develops botulism after ingesting contaminated food. Which microbial mechanism is primarily responsible for the symptoms?

Accepted Answer

Exotoxin production by Clostridium botulinum.

Question 3

Which portal of entry is most commonly associated with respiratory infections?

Accepted Answer

Mucous membranes of the respiratory tract.

Question 4

The ID$_{50}$ (infectious dose 50) is defined as:

Accepted Answer

The number of microbes required to infect 50% of a population.

Question 5

Which of the following is a key function of bacterial adhesins?

Accepted Answer

To facilitate attachment to host tissues.

Question 6

A bacterium uses its capsule to avoid phagocytosis. This is an example of which microbial mechanism?

Accepted Answer

Penetrating host defenses.

Question 7

Which of the following statements about exotoxins is TRUE?

Accepted Answer

Exotoxins are proteins secreted by bacteria that can cause specific symptoms.

Question 8

The A-B toxin mechanism involves:

Accepted Answer

An A (active) component that disrupts cell function and a B (binding) component that attaches to host cells.

Question 9

Endotoxins are most commonly associated with which type of bacteria?

Accepted Answer

Gram-negative bacteria.

Question 10

Which of the following is a major effect of endotoxins on the human body?

Accepted Answer

Fever and shock due to cytokine release.

Question 11

A patient is infected with a virus that causes cell fusion (syncytia formation) and loss of contact inhibition. Which property of viruses does this illustrate?

Accepted Answer

Cytopathic effects.

Question 12

Which of the following is a pathogenic property of fungi?

Accepted Answer

Production of mycotoxins.

Question 13

Protozoa can evade host defenses by:

Accepted Answer

Changing their surface antigens.

Question 14

Which portal of exit is most commonly used by respiratory pathogens?

Accepted Answer

Saliva and respiratory droplets.

Question 15

Plasmids can contribute to microbial pathogenicity by:

Accepted Answer

Encoding antibiotic resistance and toxin production.

Question 16

Which of the following is a real-world example of a disease caused by an exotoxin?

Accepted Answer

Tetanus caused by Clostridium tetani.

Question 17

A patient develops septic shock after a Gram-negative bacterial infection. Which component is most likely responsible?

Accepted Answer

Lipid A of lipopolysaccharide (LPS).

Question 18

Which of the following equations correctly represents the calculation of LD$_{50}$ (lethal dose 50)?

Accepted Answer

$LD_{50} = 	ext{Dose required to kill 50\% of a test population}$

Question 19

Which of the following is NOT a typical portal of entry for pathogens?

Accepted Answer

Bone marrow.

Question 20

Algae can cause disease in humans primarily by:

Accepted Answer

Producing neurotoxins.

Microbial Mechanisms of Pathogenicity: Study Notes

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