Question 1

Which of the following best describes the difference between resident and transient microbiota in the human body?

Accepted Answer

Resident microbiota are a permanent part of the normal flora, while transient microbiota are present for a short period and cannot persist due to competition and elimination by body defenses.

Question 2

Which of the following is an example of mutualism in symbiotic relationships?

Accepted Answer

Bacteria in the human colon that help digest food and receive nutrients in return.

Question 3

A patient develops a yeast infection after receiving broad-spectrum antibiotics for a bacterial infection. This is an example of which type of disease?

Accepted Answer

Iatrogenic disease

Question 4

Which of the following statements about Koch’s postulates is FALSE?

Accepted Answer

Koch’s postulates can always be ethically applied to human pathogens.

Question 5

Which of the following best explains why endotoxins are less specific and less potent than exotoxins?

Accepted Answer

Endotoxins are lipopolysaccharides released upon cell death, affecting multiple systems non-specifically.

Question 6

A researcher determines the LD50 of two bacterial species in mice: $$S. enterica$$ requires $$10^5$$ cells to kill 50% of mice, while $$S. pneumoniae$$ requires only $$10^2$$ cells. Which is more virulent?

Accepted Answer

$$S. pneumoniae$$, because it requires fewer cells to kill the host.

Question 7

Which of the following is NOT a portal of entry for pathogens into the human body?

Accepted Answer

Parenteral route is not a true portal but a means to circumvent normal portals.

Question 8

Which of the following best describes the role of fimbriae in bacterial pathogenicity?

Accepted Answer

Fimbriae facilitate adhesion to host cells and formation of biofilms, aiding in colonization and infection.

Question 9

Which of the following is a correct statement about the human microbiome?

Accepted Answer

The microbiome begins to develop during the birthing process and is largely established in the first months of life.

Question 10

Which of the following is an example of an opportunistic pathogen?

Accepted Answer

A normal microbiota organism that causes disease when introduced to an unusual site or when the immune system is suppressed.

Question 11

Which of the following is a zoonosis?

Accepted Answer

A disease that naturally spreads from animal hosts to humans, such as rabies.

Question 12

Which of the following is a distinguishing feature of exotoxins compared to endotoxins?

Accepted Answer

Exotoxins are proteins secreted by living bacteria and can be converted to toxoids for immunization.

Question 13

A patient is infected with a bacterium that produces a capsule. What is the primary advantage of the capsule for the bacterium?

Accepted Answer

The capsule prevents recognition and phagocytosis by host immune cells, increasing virulence.

Question 14

Which of the following best explains why not every contamination results in an infection?

Accepted Answer

The body’s external defenses, competition from normal microbiota, and immune responses often prevent microbes from establishing infection.

Question 15

Which of the following is a correct match between disease category and example?

Accepted Answer

Hereditary – Down syndrome

Question 16

Which of the following is a sign, not a symptom, of disease?

Accepted Answer

Fever measured by a thermometer

Question 17

Which of the following best describes the function of pili in bacteria?

Accepted Answer

Pili facilitate adhesion to host cells and are involved in genetic exchange (conjugation).

Question 18

Which of the following is a nonliving reservoir of infectious disease?

Accepted Answer

Soil contaminated with feces

Question 19

Which of the following is a correct statement about the effect of changing conditions on virulence?

Accepted Answer

Virulence can change depending on the pathogen, host, and environmental conditions.

Microbiology and Infectious Disease: Study Notes for College Students

Study Guide - Practice Questions

Study Guide - Flashcards