Question 1

Which of the following best describes the relationship between normal (resident) microflora and the human host?

Accepted Answer

Normal microflora are always present and do not cause disease under normal conditions.

Question 2

Which of the following is NOT a method by which normal microflora prevent the colonization of pathogens?

Accepted Answer

Increasing the host's body temperature

Question 3

A patient develops a urinary tract infection caused by E. coli, a bacterium normally found in the large intestine. This is an example of:

Accepted Answer

An opportunistic infection

Question 4

Which of the following is a characteristic of exotoxins?

Accepted Answer

Secreted proteins, highly specific, and produced by Gram-positive bacteria

Question 5

Which enzyme produced by bacteria allows them to penetrate host tissues by digesting the 'glue' that holds cells together?

Accepted Answer

Hyaluronidase

Question 6

A patient presents with a bull’s eye rash, fatigue, and joint pain after a tick bite. Which disease is most likely, and what is the causative agent?

Accepted Answer

Lyme disease caused by Borrelia burgdorferi

Question 7

Which of the following statements about the complement system is TRUE?

Accepted Answer

It consists of more than 30 proteins that enhance phagocytosis and lyse bacteria.

Question 8

Which antibody is the main antibody found in blood and is the only one to cross the placenta?

Accepted Answer

IgG

Question 9

A patient is diagnosed with tuberculosis. Which feature of Mycobacterium tuberculosis allows it to survive in the air for long periods?

Accepted Answer

High lipid content (mycolic acid) in the cell wall

Question 10

Which of the following best describes antigenic shift in influenza viruses?

Accepted Answer

A major change due to recombination of genetic material from different strains

Question 11

Which of the following is a correct pairing of disease and its primary mode of transmission?

Accepted Answer

Legionnaires’ disease – contaminated water aerosols

Question 12

Which of the following is a function of siderophores produced by bacteria?

Accepted Answer

Binding iron more tightly than host cells

Question 13

A patient with AIDS develops pneumonia caused by Pneumocystis jirovecii, an organism that rarely causes disease in healthy individuals. This is an example of:

Accepted Answer

An opportunistic infection

Question 14

Which of the following best describes the action of the membrane attack complex (MAC) formed by the complement system?

Accepted Answer

It forms pores in bacterial membranes, leading to cell lysis.

Question 15

Which of the following is a distinguishing feature of facultative parasites?

Accepted Answer

They can live freely but may become parasitic under certain conditions.

Question 16

Which of the following is the most effective immediate treatment for cholera?

Accepted Answer

Rapid replacement of lost fluids and electrolytes

Question 17

Which of the following is a correct statement about the ELISA test?

Accepted Answer

It detects the presence of antigens or antibodies using antigen-antibody specificity.

Question 18

Which of the following is a reason why the large intestine contains the highest number of microflora in the body?

Accepted Answer

It provides abundant nutrients and moisture.

Question 19

Which of the following is a characteristic of cutaneous anthrax?

Accepted Answer

It is acquired through a minor cut in the skin.

Question 20

Which of the following best describes the role of IgA antibodies?

Accepted Answer

They are secretory antibodies found in tears, mucus, and saliva, guarding body entrances.

Host-Microbe Interactions, Pathogenicity, and Immunity: Mini-Textbook Study Guide

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