Question 1

Which of the following best describes the function of the first line of defense in the immune system, as illustrated by the medieval castle analogy?

Accepted Answer

It includes surface barriers like skin and mucosae that prevent entry of pathogens.

Question 2

A patient presents with a cut on their skin. Which sequence of events best describes the mobilization of phagocytes to the site of injury?

Accepted Answer

Leukocytosis, margination, diapedesis, chemotaxis

Question 3

Which chemical released during inflammation is primarily responsible for vasodilation and increased capillary permeability?

Accepted Answer

Histamine

Question 4

A macrophage engulfs a rod-shaped bacterium. Which process describes the fusion of the phagosome with a lysosome, leading to destruction of the pathogen?

Accepted Answer

Phagolysosome formation

Question 5

Which of the following is TRUE regarding the complement system?

Accepted Answer

It consists of plasma proteins that, when activated, lyse microorganisms and enhance inflammation.

Question 6

A virus-infected cell releases interferons. What is the primary effect of these interferons on neighboring cells?

Accepted Answer

They stimulate neighboring cells to produce antiviral proteins that block viral replication.

Question 7

Which immunoglobulin class is most abundant in plasma and is responsible for conferring passive immunity from mother to fetus?

Accepted Answer

IgG

Question 8

What is the primary mechanism by which antibodies neutralize pathogens?

Accepted Answer

By blocking specific sites on viruses or toxins, preventing their attachment to body cells

Question 9

Which equation best represents the relationship between antibody concentration and time during a primary and secondary immune response?

Accepted Answer

Antibody concentration increases rapidly after secondary exposure: $$A(t) = A_0$ e$$^{kt}$$

Question 10

Which of the following best describes the role of MHC proteins in antigen presentation?

Accepted Answer

Class I MHC proteins present endogenous antigens to CD8 cells, while class II MHC proteins present exogenous antigens to CD4 cells.

Question 11

A patient receives a mismatched blood transfusion. Which type of hypersensitivity reaction is most likely to occur?

Accepted Answer

Type II (cytotoxic) hypersensitivity

Question 12

Which process ensures that T cells do not attack self-antigens during their maturation in the thymus?

Accepted Answer

Negative selection, which eliminates self-reactive T cells via apoptosis

Question 13

Which of the following is a function of helper T cells (TH cells) in the adaptive immune response?

Accepted Answer

Activating B cells and other T cells by releasing cytokines

Question 14

Which equation describes the rate of antibody production by plasma cells during a primary immune response?

Accepted Answer

Rate = $$2000 	ext{ antibodies/sec}$$ for $$4 to$$ $$5$$ days

Question 15

Which of the following is a characteristic of passive humoral immunity?

Accepted Answer

It provides immediate protection but does not generate immunological memory.

Question 16

Which immunoglobulin class is most likely to be elevated during a severe allergic reaction?

Accepted Answer

IgE

Question 17

Which process describes the tagging of pathogens with opsonins to enhance phagocytosis?

Accepted Answer

Opsonization

Question 18

A patient with AIDS has a deficiency in which type of immune cell, leading to impaired adaptive immunity?

Accepted Answer

Helper T cells (TH cells)

Question 19

Which equation best represents the effect of fever on metabolic rate?

Accepted Answer

Metabolic rate increases as temperature increases: $$M(T) = M_0$ + kT$$

Question 20

Which of the following best explains why autoimmune diseases may develop after a streptococcal infection?

Accepted Answer

Antibodies produced against streptococcal antigens cross-react with self-antigens, causing tissue damage.

The Immune System: Innate and Adaptive Body Defenses

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