Question 1

A hospital patient develops a urinary tract infection (UTI) after being catheterized during their stay. Which term best describes this type of infection?

Accepted Answer

Nosocomial infection

Question 2

Which of the following best distinguishes between incidence and prevalence of an infectious disease?

Accepted Answer

Incidence measures new cases over a period of time, while prevalence measures all existing cases at a specific time.

Question 3

A disease that is constantly present at a low level in a specific geographic area is best described as:

Accepted Answer

Endemic

Question 4

Which of the following is an example of a mutualistic relationship between humans and microorganisms?

Accepted Answer

Escherichia coli in the gut producing vitamin K for the host

Question 5

Which of the following best describes the difference between pathogenicity and virulence?

Accepted Answer

Pathogenicity is the ability to cause disease, while virulence is the degree of damage caused.

Question 6

A patient contracts influenza after touching a contaminated doorknob and then touching their nose. Which portal of entry did the pathogen use?

Accepted Answer

Respiratory tract

Question 7

Which of the following is NOT a physical barrier to infection?

Accepted Answer

Lysozyme in tears

Question 8

Which cell type is primarily responsible for phagocytosis during the innate immune response?

Accepted Answer

Neutrophils

Question 9

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

Accepted Answer

It can directly lyse bacterial cells by forming the membrane attack complex.

Question 10

A patient is exposed to a pathogen for the first time and develops symptoms after several days. Which feature of the adaptive immune response explains why a second exposure to the same pathogen results in a faster and stronger response?

Accepted Answer

Memory

Question 11

Which of the following best describes the role of CD8+ T lymphocytes in the adaptive immune response?

Accepted Answer

They directly kill infected host cells presenting antigen with MHC class I.

Question 12

Which of the following is a correct statement about antigen presentation and MHC restriction?

Accepted Answer

CD4+ T cells recognize antigens presented by MHC class II molecules.

Question 13

Which of the following is a function of antibodies in the immune response?

Accepted Answer

Opsonizing pathogens to enhance phagocytosis

Question 14

A patient with a genetic deficiency in natural killer (NK) cells would be most susceptible to which type of infection?

Accepted Answer

Viral infections and tumor formation

Question 15

Which of the following best describes the difference between humoral and cellular immunity?

Accepted Answer

Humoral immunity is mediated by antibodies produced by B cells, while cellular immunity is mediated by T cells.

Question 16

Which of the following is a characteristic of the innate immune system but NOT the adaptive immune system?

Accepted Answer

Immediate response to pathogens

Question 17

A patient is bitten by a mosquito carrying the malaria parasite. Which route of transmission and portal of entry does this represent?

Accepted Answer

Vector-borne; parenteral route

Question 18

Which of the following is a common reservoir for Salmonella typhi, the causative agent of typhoid fever?

Accepted Answer

Humans

Question 19

Which of the following best explains why fever can be beneficial during an infection?

Accepted Answer

Fever enhances the activity of immune cells and inhibits the growth of some pathogens.

Question 20

A patient is exposed to a bacterial pathogen and produces IgM antibodies within a week. Upon a second exposure months later, the patient rapidly produces high levels of IgG antibodies. Which immunological principle does this scenario illustrate?

Accepted Answer

Secondary immune response

Host-Microbe Interactions and the Immune Response to Infectious Disease

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