Question 1

Which of the following best describes the primary difference between innate and adaptive immunity?

Accepted Answer

Innate immunity provides a rapid, broad-spectrum response using preset receptors, while adaptive immunity is slower but highly specific and develops memory.

Question 2

A patient is exposed to a novel virus. Which of the following events occurs FIRST in their immune response?

Accepted Answer

Recognition of viral components by Toll-like receptors (TLRs) on innate immune cells.

Question 3

Which enzyme found in tears and saliva is responsible for digesting bacterial cell walls, and what is its primary target?

Accepted Answer

Lysozyme; it targets peptidoglycan in bacterial cell walls.

Question 4

A genetic mutation prevents the expression of CD4 accessory proteins on T cells. Which of the following is the most likely consequence?

Accepted Answer

Helper T cells cannot be activated, severely impairing both humoral and cell-mediated adaptive responses.

Question 5

Which of the following best explains why a new strain of influenza virus resulting from gene exchange with a swine flu virus can evade immunity from a previous year's flu shot?

Accepted Answer

The new strain expresses different surface epitopes due to antigenic variation, so memory B and T cells from the previous infection or vaccination do not recognize it.

Question 6

Which of the following is a function of antibodies in the humoral immune response?

Accepted Answer

They neutralize pathogens by blocking their entry into host cells.

Question 7

A researcher discovers a bacterium with a capsule that prevents binding by innate immune receptors. Why is this bacterium particularly dangerous during the primary immune response?

Accepted Answer

The innate immune system cannot recognize or respond to the bacterium, delaying the adaptive response and allowing the pathogen to proliferate unchecked.

Question 8

Which class of antibody is most abundant in blood and is primarily responsible for long-term immunity?

Accepted Answer

IgG

Question 9

What is the role of the enzyme complex RAG in the development of B cells?

Accepted Answer

It facilitates the random recombination of V (variable), J (joining), and C (constant) gene segments to generate diverse antigen receptors.

Question 10

Which of the following best describes the function of cytotoxic T cells in the immune response?

Accepted Answer

They recognize antigens presented by MHC I molecules and induce apoptosis in infected host cells.

Question 11

Which of the following is a key feature of the inflammatory response?

Accepted Answer

Mast cells release histamine, increasing capillary permeability and causing redness and swelling.

Question 12

Which of the following best explains why herpes simplex virus can remain undetected in sensory neurons?

Accepted Answer

Sensory neurons express very few Class I MHC molecules, making them less visible to cytotoxic T cells.

Question 13

Which process describes the marking of a pathogen by antibodies to enhance its uptake and destruction by phagocytes?

Accepted Answer

Opsonization

Question 14

A patient with severe combined immunodeficiency (SCID) lacks functional lymphocytes. Which aspect of their immune response is most compromised?

Accepted Answer

Both humoral and cell-mediated adaptive immunity are severely impaired.

Question 15

Which of the following is TRUE regarding the role of MHC molecules in antigen presentation?

Accepted Answer

Class I MHC molecules present antigens to cytotoxic T cells, while Class II MHC molecules present antigens to helper T cells.

Question 16

Which of the following best describes the process of clonal selection in adaptive immunity?

Accepted Answer

Only lymphocytes with receptors specific to an encountered antigen are activated to proliferate and differentiate.

Question 17

Which antibody class is primarily responsible for allergic reactions and binds to mast cells, triggering histamine release?

Accepted Answer

IgE

Question 18

Which of the following best explains why the adaptive immune response is dependent on the innate immune system?

Accepted Answer

The innate system provides immediate defense and presents antigens to activate the adaptive response.

Question 19

Which of the following is a characteristic of autoimmune diseases?

Accepted Answer

The immune system loses self-tolerance and attacks the body's own tissues.

Question 20

A plasma cell can secrete approximately how many antibodies per second during its lifespan?

Accepted Answer

$$2 	imes 10^3$

Chapter 43: The Immune System – Guided Study and Practice

Study Guide - Practice Questions

Study Guide - Flashcards