Question 1

Which of the following best describes the role of the skin in the immune system's first line of defense?

Accepted Answer

It acts as a physical barrier and secretes chemicals like keratin and acid mantle to inhibit microbial growth.

Question 2

A patient with a genetic defect in Toll-like receptors (TLRs) would most likely have impaired:

Accepted Answer

Recognition and response to common microbial patterns, reducing innate immune activation.

Question 3

Which process enhances phagocytosis by marking pathogens with antibodies or complement proteins?

Accepted Answer

Opsonization

Question 4

During inflammation, which chemical is primarily responsible for vasodilation and increased vascular permeability?

Accepted Answer

Histamine

Question 5

A patient receives a mismatched blood transfusion and develops a reaction within 2 hours. Which type of hypersensitivity is this?

Accepted Answer

Type II (Cytotoxic) hypersensitivity

Question 6

Which equation best represents the process of clonal selection in B cells after antigen exposure?

Accepted Answer

$$B_{naive} + Ag \rightarrow B_{activated} \rightarrow Plasma\ Cells + Memory\ B\ Cells$$

Question 7

Which of the following is TRUE regarding the difference between humoral and cellular immunity?

Accepted Answer

Humoral immunity involves antibodies produced by B cells, while cellular immunity involves direct action by T cells.

Question 8

Which class of MHC protein is displayed by all nucleated cells except red blood cells and is recognized by cytotoxic T cells?

Accepted Answer

Class I MHC

Question 9

A child is born with severe combined immunodeficiency (SCID). Which immune cells are most affected?

Accepted Answer

B cells and T cells

Question 10

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

Accepted Answer

Fever causes the liver and spleen to sequester iron and zinc, limiting microbial growth.

Question 11

Which equation describes the activation of the complement system via the classical pathway?

Accepted Answer

$$Antibody + Antigen \rightarrow Antibody-Antigen\ Complex \rightarrow Complement\ Activation$$

Question 12

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

Accepted Answer

Activate B cells and cytotoxic T cells by secreting cytokines.

Question 13

A person exposed to poison ivy develops a skin reaction 2 days later. Which immune mechanism is responsible?

Accepted Answer

Type IV (Delayed) hypersensitivity mediated by T cells

Question 14

Which of the following best describes the process of antigen presentation to T cells?

Accepted Answer

Antigen-presenting cells (APCs) engulf antigens and display fragments on MHC proteins for T cell activation.

Question 15

Which equation represents the process of antibody neutralization?

Accepted Answer

$$Antibody + Antigen \rightarrow Antigen-Antibody\ Complex \rightarrow Blocked\ Pathogen\ Binding$$

Question 16

Which of the following is a key difference between active and passive humoral immunity?

Accepted Answer

Passive immunity involves the transfer of ready-made antibodies and does not generate immunological memory.

Question 17

A patient with HIV is most likely to have a deficiency in which immune cell type, leading to increased susceptibility to opportunistic infections?

Accepted Answer

Helper T cells (Th)

Question 18

Which of the following mechanisms is used by cytotoxic T cells to kill infected target cells?

Accepted Answer

Release of perforins and granzymes to induce apoptosis.

Question 19

Which equation best represents the process of inflammation following tissue injury?

Accepted Answer

$$Injury \rightarrow Release\ of\ Inflammatory\ Chemicals \rightarrow Vasodilation + Increased\ Permeability \rightarrow Phagocyte\ Mobilization$$

Question 20

Which of the following is a common cause of autoimmunity according to the study materials?

Accepted Answer

Foreign antigens that resemble self-antigens, leading to cross-reactivity.

The Immune System: Innate and Adaptive Body Defenses

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