Question 1

An advantage of innate immunity is ________.

Accepted Answer

Innate immunity includes physical and chemical barriers that prevent pathogens from entering into the body, such as the skin and mucous membranes. This is a major advantage because it provides a first line of defense against pathogens, reducing the likelihood of infection.

Question 2

Antibodies typically act extracellularly in body fluids and are therefore considered part of the humoral branch of adaptive immunity.

Accepted Answer

Antibodies are secreted by B cells and act extracellularly in body fluids, such as blood and lymph. They are therefore considered part of the humoral branch of adaptive immunity.

Question 3

Without the positive selection process in lymphocyte maturation ________.

Accepted Answer

Positive selection ensures that T-cells can recognize self-MHC molecules, which is necessary for them to bind to antigen-presenting cells (APCs) and become activated. Without this process, T-cells would not be able to properly bind to APCs.

Question 4

Choose the best description of an antigen.

Accepted Answer

An antigen is a particle that triggers the adaptive immune response. It is recognized as foreign by the immune system and leads to the production of specific antibodies to fight against it. Option A is partially correct, but not all antigens necessarily come from pathogens. Option C is incorrect as not all antigens trigger inflammation. Option D is also incorrect, as no antigen itself enhances or modifies the immune response, but rather triggers it.

Question 5

Vaccines work by ________.

Accepted Answer

Vaccines work by priming the adaptive immunity with a relatively harmless primary exposure. This allows the immune system to recognize and prepare to fight the real infectious agent if and when it is encountered in the future.

Question 6

Select the best description of the negative selection process of lymphocyte maturation.

Accepted Answer

Negative selection involves the removal of lymphocytes that react with "self" cells to prevent autoimmunity. The process is important in ensuring that only self-tolerant lymphocytes remain in circulation. Option A is not correct since it is more descriptive of positive selection. Option B is incorrect because it involves teaching instead of the elimination of cells. Option D is also incorrect since MHC proteins are important for antigen recognition and activation of T cells, and their absence would be detrimental.

Question 7

Allergens differ from antigens because ________.

Accepted Answer

Allergens cause an exaggerated immune response that results in allergy symptoms, even though they are generally harmless particles. Antigens, on the other hand, can be bacterial or viral in nature and stimulate the immune system to produce antibodies to fight off the foreign invader. Allergens are not restricted to plants and can be derived from other sources as well. Allergens do involve the activation of certain types of leukocytes, particularly mast cells and eosinophils, which are responsible for the inflammatory response.

Question 8

Which of the following best describes the qualities of most antigens?

Accepted Answer

Antigens are macromolecules that are foreign to the host and can trigger an immune response. Examples of antigens include proteins, polysaccharides, and nucleic acids from bacteria, viruses, and other pathogens. They can also be found on the surface of cancer cells or transplanted tissues. It is important to note that not all foreign macromolecules are antigens, only those that elicit an immune response.

Question 9

All of the following are true of the classical pathway of complement activation except one.Select the one answer that does not describe the classical pathway of complement activation.

Accepted Answer

The classical pathway of complement activation does not activate T-helper cells by presenting antigen to them. This is a function of the adaptive immune system, whereas the classical pathway is an example of overlap between innate and adaptive immune function. The other options are true of the classical pathway - it requires the binding of antibodies to antigens, results in enhanced inflammation, opsonization, and formation of MAC proteins.

Question 10

B-lymphocytes are categorized as part of the adaptive branch of the immune system for all of the following reason but one.Which of the following is not one of the reasons B-lymphocytes are considered part of the adaptive immunity?

Accepted Answer

B-lymphocytes are not considered a first line of defense as they are part of the adaptive immunity, which is a slower response that develops after exposure to a pathogen. The other options are all correct reasons why B-lymphocytes are part of the adaptive immunity.

Question 11

Which of the following examples below describes an autoimmune disease?

Accepted Answer

Antibody binding to acetylcholine receptors is a hallmark of Myasthenia Gravis, which is an autoimmune disease. In this condition, the immune system mistakenly attacks the body's own acetylcholine receptors, leading to muscle weakness.

The other options describe different mechanisms of disease that are not related to autoimmune processes. A describes a toxin-mediated disease, B describes an autoimmune disorder, C describes a viral infection that leads to immunodeficiency, and D describes cancer.

Question 12

Membrane attack complex (MAC)kills by ________.

Accepted Answer

The membrane attack complex (MAC) is a group of complement proteins that form a pore in the bacterial plasma membrane, disrupting the selectively permeability and causing it to leak, which eventually leads to bacterial cell death.

Question 13

Overlap in the innate and adaptive immune system is seen in all of the following examples but one.Which of the following examples does not illustrate the overlap of innate and adaptive immune responses?

Accepted Answer

NK cells causing apoptosis of an abnormal host cell, lacking MHC proteins, is an example of the innate immune system's function and does not illustrate an overlap with the adaptive immune system. NK cells can recognize and eliminate cells without the need for prior sensitization, which is a characteristic of innate immunity.

Question 14

Inflammation ________.

Accepted Answer

Inflammation brings more leukocytes (white blood cells) to the site of infection to fight off the invading pathogen. Option A and C are incorrect because inflammation is a natural response of the body's immune system and not caused by bacterial or viral activity to enhance the spread of disease. Option D is partially correct as swelling can impair bodily function, but inflammation can also aid in the healing process.

Question 15

During inflammation fluids will passively diffuse out of blood vessels into the nearby,infected tissues.This implies all of the following except ________.

Accepted Answer

The passage does not provide any information about B-lymphocytes differentiating to become plasma cells.

Question 16

A flu vaccine is needed seasonally to be effective but a polio vaccine is only needed once.The best explanation of this is ________.

Accepted Answer

The flu has several strains that change seasonally, which means that a new flu vaccine must be developed each year to target the specific strains that are expected to be prevalent in the upcoming flu season. In contrast, there is only one type of polio virus, so once someone is vaccinated against it, they are protected for life.

Question 17

Which of the following does not describe actions of interferon (IFN)?

Accepted Answer

IFN cannot penetrate the viral capsid and destroy the virus. It primarily acts by binding to normal, uninfected cells and stimulating the production of anti-viral proteins, as described in option A. Option C is also correct, as virally infected cells can release IFN which attracts NK cells to attack and kill the infected cell. Option D is also true, as IFN can attract macrophages to the secreting cell to be removed by phagocytosis.

Question 18

An advantage to adaptive immunity is ________.

Accepted Answer

Adaptive immunity's memory cells allow for a quicker, larger and more efficient immune response upon second exposure to an antigen, which can help protect the body against future infections.

Question 19

A vaccine is effective because ________.

Accepted Answer

A vaccine works by priming the immune system with a weakened or inactivated form of a pathogen, which allows the body to produce a memory of the pathogen and generate a faster and more efficient secondary immune response if it encounters the actual pathogen in the future. This is because during the primary immune response, B-lymphocytes undergo differentiation and activation, whereas during the secondary response, memory B-cells are already present and can rapidly produce large amounts of specific antibodies.

Question 20

All but one of the following occur during the inflammatory response.Select the example below that does not describe the process of inflammation.

Accepted Answer

Vasoconstriction is a response to injury but is not part of the inflammatory response. It occurs immediately after injury to prevent blood loss. The other options mentioned (B, C, and D) are all examples of processes that occur during the inflammatory response.

Quiz 21: The Immune System: Innate and Adaptive Body Defenses