Question 1

According to the hygiene hypothesis, which of the following best explains the increased prevalence of allergies and asthma in urban populations compared to rural populations?

Accepted Answer

Urban populations have limited exposure to diverse microbes, resulting in lower immune tolerance and increased hypersensitivity.

Question 2

Which of the following statements about dysbiosis is correct?

Accepted Answer

Dysbiosis is an imbalance in the microbiota that can lead to adverse effects such as Clostridioides difficile infection.

Question 3

A patient with Crohn’s disease is treated with whipworm eggs. What is the proposed mechanism by which this therapy works?

Accepted Answer

Whipworm eggs suppress T helper cell pathways, reducing inflammation.

Question 4

Which of the following is a real-world application of fecal transplants?

Accepted Answer

Restoring healthy gut microbiota in patients with Clostridioides difficile infection.

Question 5

Which of the following mediators is released during mast cell degranulation in a Type I (anaphylactic) hypersensitivity reaction and increases the permeability of blood capillaries?

Accepted Answer

Histamine

Question 6

A person experiences systemic anaphylaxis after being stung by a bee. Which treatment is most effective for reversing the shock?

Accepted Answer

Epinephrine

Question 7

Which equation best represents the relationship between the concentration of IgG blocking antibodies and the effectiveness of desensitization therapy for allergies?

Accepted Answer

$$E = k 	imes [IgG]$$

Question 8

A patient with blood type O receives a transfusion of type A blood. Which hypersensitivity reaction is most likely to occur, and what is the mechanism?

Accepted Answer

Type II hypersensitivity; IgG or IgM antibodies activate complement, causing cell lysis

Question 9

Hemolytic disease of the newborn (HDNB) occurs when an Rh− mother has an Rh+ fetus. Which preventive measure is used to avoid this condition?

Accepted Answer

Giving RhoGAM® shots to the mother at 28 weeks and after delivery

Question 10

Which of the following best describes the mechanism of Type III (immune complex) hypersensitivity reactions?

Accepted Answer

Antibodies form against soluble antigens, creating immune complexes that activate complement and cause inflammation.

Question 11

A patient develops allergic contact dermatitis after exposure to poison ivy. Which process is responsible for this delayed hypersensitivity reaction?

Accepted Answer

Haptens combine with skin proteins, activating T memory cells to release cytokines.

Question 12

Which equation best represents the time delay in Type IV hypersensitivity reactions after antigen exposure?

Accepted Answer

$$t_{delay} = t_{migration} + t_{accumulation}$$

Question 13

Which of the following is a characteristic of autoimmune diseases?

Accepted Answer

Immune system responds to self-antigens, causing organ damage.

Question 14

DiGeorge syndrome is an example of which type of immunodeficiency, and what is its primary defect?

Accepted Answer

Congenital immunodeficiency; lack of thymus and failure to develop cell-mediated immunity

Question 15

Which of the following best describes the structure of HIV?

Accepted Answer

Two identical + stranded RNA genomes, reverse transcriptase, integrase, phospholipid envelope, gp120 glycoprotein spikes

Question 16

Which equation best represents the rate of HIV mutation, contributing to its rapid antigenic changes?

Accepted Answer

$$R_{mutation} = \mu 	imes N_{replication}$$

Question 17

Which diagnostic method can detect HIV infection before antibodies are present, and what is the principle behind it?

Accepted Answer

Nucleic acid amplification tests (NAATs); detect HIV RNA using real-time PCR

Question 18

Which of the following is the most common mode of HIV transmission worldwide?

Accepted Answer

Heterosexual transmission

Question 19

Highly active antiretroviral therapy (HAART) is used to treat HIV infection. What is the primary goal of HAART?

Accepted Answer

To minimize the survival of resistant HIV strains by using multiple drugs simultaneously

Disorders Associated with the Immune System: Hypersensitivity, Autoimmunity, and HIV/AIDS

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