Question 1

Which of the following best describes the role of the skin in non-specific resistance?

Accepted Answer

It acts as a physical barrier with tightly packed cells containing keratin, preventing microbial entry.

Question 2

A patient with a genetic defect that prevents the production of lysozyme would be most susceptible to which of the following?

Accepted Answer

Increased risk of bacterial infections due to impaired chemical defense in tears and saliva.

Question 3

Which of the following is NOT a chemical factor involved in non-specific resistance?

Accepted Answer

Cilia

Question 4

During the process of phagocytosis, which stage is directly enhanced by opsonization?

Accepted Answer

Adherence

Question 5

A laboratory test shows a high percentage of eosinophils in a patient's blood. This finding is most consistent with which type of infection?

Accepted Answer

Parasitic infection

Question 6

Which of the following best explains how a bacterial capsule helps a microbe evade the immune system?

Accepted Answer

It prevents adherence by making the microbe too slippery for phagocytes to grab.

Question 7

Which of the following is the correct sequence of events in inflammation?

Accepted Answer

Vasodilation and increased permeability → Phagocyte migration and emigration → Tissue repair

Question 8

A patient develops a fever after a bacterial infection. Which of the following best describes the physiological cause of this fever?

Accepted Answer

The hypothalamus is signaled by pyrogens to reset the body's thermostat higher.

Question 9

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

Accepted Answer

It can be activated by three pathways: classical, alternative, and lectin.

Question 10

Which of the following is a result of complement activation that directly leads to the lysis of a microbe?

Accepted Answer

Formation of the membrane attack complex (MAC) by C5b-C9

Question 11

Which of the following best differentiates between non-specific (innate) and specific (adaptive) immunity?

Accepted Answer

Non-specific immunity has no memory and treats all invaders the same, while specific immunity recognizes specific antigens and has memory.

Question 12

Which antibody class is most abundant in serum and is the only one that can cross the placenta?

Accepted Answer

IgG

Question 13

A newborn receives antibodies from its mother through breast milk. This is an example of which type of acquired immunity?

Accepted Answer

Naturally acquired passive immunity

Question 14

Which of the following best describes the function of MHC class II molecules?

Accepted Answer

They are found only on antigen-presenting cells and present antigens to CD4+ T cells.

Question 15

Which of the following is a correct description of the clonal selection theory?

Accepted Answer

A B cell that binds its specific antigen proliferates into plasma cells and memory cells.

Question 16

Which of the following is a function of TH2 cells?

Accepted Answer

Stimulating B cells to produce antibodies

Question 17

A patient is exposed to a pathogen for the first time. Which antibody is produced first and what is its main structural feature?

Accepted Answer

IgM; pentamer

Question 18

Which of the following best describes the process of antibody-dependent cell-mediated cytotoxicity (ADCC)?

Accepted Answer

Antibodies coat a large parasite, allowing NK cells and eosinophils to attack it from the outside.

Question 19

Which of the following is TRUE regarding T-independent antigens?

Accepted Answer

They often have repeating units and can activate B cells directly, but produce a weaker response with no memory.

Question 20

A scientist is developing a monoclonal antibody therapy. Which of the following best describes monoclonal antibodies?

Accepted Answer

They are laboratory-produced antibodies that are all identical and specific to one target.

Microbiology Immunity and Host Defense Study Guide – Step-by-Step Guidance

Study Guide - Practice Questions