Question 1

Which of the following best describes self-tolerance in the immune system?

Accepted Answer

The ability of immune cells to avoid attacking normal self-cells by distinguishing self from foreign antigens.

Question 2

A patient is exposed to a pathogen but does not develop symptoms. Which statement best explains this outcome?

Accepted Answer

The patient is immune to the pathogen due to adaptive immune responses.

Question 3

Which of the following is NOT a similarity shared by innate and adaptive immunity?

Accepted Answer

Both tailor their response to specific antigens.

Question 4

According to the hygiene hypothesis, what is the effect of reduced microbial diversity in the normal microbiota?

Accepted Answer

It may negatively affect immune response, leading to increased risk of immune disorders.

Question 5

Which of the following is a chemical barrier in the first line of innate defenses?

Accepted Answer

Lysozyme in tears

Question 6

Defensins are classified as antimicrobial peptides (AMPs). What is their primary mechanism of action?

Accepted Answer

They insert themselves into microbial cell membranes, causing rapid cell death.

Question 7

Which tissue is considered the main physical barrier in animals against pathogen entry?

Accepted Answer

Epithelial tissue

Question 8

A patient presents with swollen lymph nodes during an infection. What is the most likely cause of this swelling?

Accepted Answer

Rapid multiplication of leukocytes in the lymph node to combat the infection.

Question 9

Which of the following is a primary lymphoid tissue?

Accepted Answer

Thymus

Question 10

Which leukocyte is the most abundant in the blood and is the first recruited to injured tissues?

Accepted Answer

Neutrophils

Question 11

A patient’s blood test shows neutropenia. Which type of infection is most likely responsible?

Accepted Answer

Certain viral infections

Question 12

Which cell type releases histamine and plays a key role in allergies and fighting parasites?

Accepted Answer

Mast cells

Question 13

Natural killer (NK) cells are classified as lymphocytes. Which statement best describes their role?

Accepted Answer

They directly kill virus-infected and tumor cells as part of innate immunity.

Question 14

Which complement pathway is triggered by antibodies bound to an invading agent?

Accepted Answer

Classical pathway

Question 15

What is the outcome of complement protein C5b (with C6, C7, C8, and C9) forming a membrane attack complex (MAC)?

Accepted Answer

Cytolysis of the pathogen by drilling into its membrane and causing cell lysis

Question 16

A microbe produces siderophores. What is the primary function of these molecules?

Accepted Answer

To extract iron from host iron-binding proteins without breaking them down.

Question 17

Which cytokine is primarily produced by macrophages and is known for stimulating inflammation and killing tumor cells?

Accepted Answer

Tumor necrosis factor alpha (TNF-\alpha)

Question 18

During inflammation, which two steps allow leukocytes to exit blood vessels and enter tissues?

Accepted Answer

Margination and diapedesis

Question 19

A patient is prescribed NSAIDs for inflammation. What is the mechanism by which NSAIDs reduce pain and inflammation?

Accepted Answer

They reduce eicosanoid production, which decreases inflammation and pain.

Question 20

A fever is induced by pyrogens signaling the hypothalamus. What is the risk associated with fevers above $$105^\circF$$?

Accepted Answer

They cause denaturation of essential cellular enzymes and proteins, leading to life-threatening conditions.

Question 21

Which of the following best describes the process of opsonization?

Accepted Answer

Complement proteins tag pathogens, making them more readily cleared by phagocytic cells.

Innate Immunity and Immune System Study Guide – Step-by-Step Guidance

Study Guide - Practice Questions