Question 1

The cell-mediated immunity that destroys virally infected cells primarily involves ________.
A) cytotoxic T cells
B) inflammation
C) phagocytosis
D) macrophages
E) B cells

Accepted Answer

Cell-mediated immunity involves the activation of cytotoxic T cells, which recognize and destroy virally infected cells. This process does not involve B cells, phagocytosis, or macrophages. Inflammation can play a role in activating the immune response, but it is not the primary mechanism for destroying infected cells.

Question 2

Use the following information to answer the question(s) below.
An otherwise healthy student in your class is infected with EBV, the virus that causes infectious mononucleosis. The same student had already been infected when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though infected, she does not get sick.
-Her immune system's recognition of the second infection involves memory ________.
A) helper T cells
B) natural killer cells
C) plasma cells
D) cytotoxic T cells

Accepted Answer

Memory cytotoxic T cells are responsible for recognizing and destroying infected cells during a second infection.

Question 3

A function of antibodies is to ________.
A) inject toxins into living pathogens
B) secrete cytokines that attract macrophages to infection sites
C) release major histocompatibility proteins to disrupt infected cells
D) act as Toll-like receptors
E) mark pathogenic cells for destruction

Accepted Answer

Antibodies mark pathogenic cells for destruction by binding to specific antigens on their surface and triggering the immune system to recognize and eliminate them.

Question 4

For the successful development of a vaccine to be used against a pathogen, it is necessary that ________.
A) the surface antigens of the pathogen stay the same
B) a rearrangement of the B-cell receptor antibodies takes place
C) all of the surface antigens on the pathogen be identified
D) the pathogen have only one epitope
E) the major histocompatibility (MHC) molecules are heterozygous

Accepted Answer

The surface antigens of the pathogen must remain the same in order to develop a successful vaccine. This is because vaccines work by exposing the immune system to a harmless form of the pathogen, in order to train it to recognize and respond to the pathogen if it is encountered again in the future. If the surface antigens of the pathogen change, the immune system may not be able to recognize and respond to the pathogen effectively.

Question 5

Which of the following cells are involved in cell-mediated immunity and also respond to class I MHC molecule-antigen complexes?
A) cytotoxic T cells
B) plasma cells
C) helper T cells
D) macrophages
E) B cells

Accepted Answer

Cytotoxic T cells are involved in cell-mediated immunity and respond to class I MHC molecule-antigen complexes. Choice B (plasma cells) secretes antibodies and does not respond to MHC molecule-antigen complexes. Choice C (helper T cells) responds to class II MHC molecule-antigen complexes. Choice D (macrophages) present antigens to T cells via MHC molecules but do not respond to them. Choice E (B cells) are involved in humoral immunity and do not directly participate in cell-mediated immunity.

Question 6

Which of the following is a difference between class I and class II major histocompatibility complex (MHC) proteins?
A) Class I MHC proteins can be found on most cell types, whereas both class I and II MHC proteins are found on the antigen-presenting cells of the immune system
B) Class I MHC proteins are added to antigens in the cytoplasm, whereas class II proteins are added to antigens in the Golgi apparatus.
C) Class I MHC proteins signal the immune system to activate the cell displaying the message, whereas class II proteins signal the immune system to destroy a particular cell.
D) Class I and class II MHC proteins have the same basic role, but individuals with particularly strong immune systems will have both types, whereas most individuals have just one or the other.

Accepted Answer

Class I MHC proteins can be found on most cell types, whereas both class I and II MHC proteins are found on the antigen-presenting cells of the immune system. This is a key difference between the two classes of MHC proteins.

B, C, and D are incorrect:
B: Both class I and II MHC proteins are added to antigens in the endoplasmic reticulum, not the cytoplasm or Golgi apparatus.
C: Both class I and II MHC proteins play a role in signaling the immune system, but the specific signals are different, and neither signal necessarily indicates destruction of a cell. 
D: Most individuals have both class I and class II MHC proteins, although some individuals may have certain variations or mutations that affect their MHC protein expression.

Question 7

Your sister-in-law never gets sick, while her male neighbor seems to be sick all the time. Although there are several possible explanations for this, one is that they are genetically different. Which of the following hypotheses concerning genetic inheritance of major histocompatibility complex (MHC) molecules is consistent with this observation and your understanding of the immune system?
A) Individuals who are homozygous dominant for MHC genes are healthier than those who are homozygous recessive for MHC genes.
B) In the case of MHC, it is beneficial to have as many different alleles as possible, so individuals heterozygous for the multiple MHC genes are healthier than those who are mainly homozygous for MHC genes.
C) MHC proteins are often closely associated with small antigen particles that have been broken off the main pathogen, so individuals who are recessive for MHC don't normally have many illnesses because they don't produce these MHC-antigen complexes.
D) Some individuals undergo greater levels of somatic hypermutation for the MHC genes.

Accepted Answer

MHC molecules play a crucial role in the immune system by presenting antigens to T cells. Having multiple different MHC alleles would increase the chances of being able to detect a wider variety of antigens, thus improving the overall effectiveness of the immune system. Therefore, individuals who are heterozygous for the multiple MHC genes are healthier than those who are mainly homozygous for MHC genes.

Question 8

Which of the following is a difference between B cells and T cells?
A) One has a major role in antibody production, while the other has a major role in cytotoxicity.
B) One binds a receptor called BCR (B-cell receptor), while the other recognizes a receptor called TCR (T-cell receptor).
C) B cells are activated by free-floating antigens in the blood or lymph. T cells are activated by plasma cells.
D) T cells are produced in the thymus and B cells are produced in the bone marrow.

Accepted Answer

The answer of Which of the following is a difference...

Question 9

Phagocytosis of microbes by macrophages is enhanced by ________.
I. the binding of antibodies to the surface of microbes
II. antibody-mediated agglutination of microbes
III. the release of cytokines by activated B cells
A) only I and II
B) only II and III
C) only I and III
D) I, II, and, III

Accepted Answer

The binding of antibodies to the surface of microbes (opsonization) and antibody-mediated agglutination both enhance phagocytosis by making microbes more recognizable and easier to engulf by macrophages. Cytokines released by B cells do not directly enhance phagocytosis.

Question 10

Secondary immune responses upon a second exposure to a pathogen are due to the activation of ________.
A) memory cells
B) macrophages
C) stem cells
D) B cells
E) T cells

Accepted Answer

Memory cells are formed during the primary immune response and are able to quickly activate upon a second exposure to the same pathogen, leading to a more rapid and robust secondary immune response. Macrophages, stem cells, B cells, and T cells all play important roles in the immune response, but memory cells are specifically responsible for the secondary immune response.

Question 11

A cell type that interacts with both the humoral and cell-mediated immune pathways is a ________.
A) plasma cell
B) cytotoxic T cell
C) natural killer cell
D) CD8 cell
E) helper T cell

Accepted Answer

Helper T cells interact with both the humoral and cell-mediated immune pathways by synthesizing and secreting cytokines, which activate other immune cells such as B cells (for humoral immunity) and cytotoxic T cells (for cell-mediated immunity).

Question 12

Why might humans need yearly vaccination for influenza?
A) There has been an increase in immunodeficiency diseases.
B) Influenza typically causes anaphylactic shock.
C) Memory B cells die out after one year.
D) Influenza virus undergoes rapid mutation that alters the surface proteins in the cells it infects.
E) Influenza initiates autoimmune disorders.

Accepted Answer

Influenza virus undergoes rapid mutation that alters the surface proteins in the cells it infects, which makes it difficult for the immune system to recognize and fight off the virus from previous infections. Therefore, yearly vaccination is required to protect individuals from new strains of the virus.

Question 13

Which of the following is crucial to activation of the adaptive immune response?
A) memory cells
B) presentation of MHC (major histocompatibility complex)-antigen complex on a cell surface
C) somatic hypermutation
D) phagocytosis of antibody-antigen complex by macrophages in the blood (the humoral response)

Accepted Answer

Presentation of MHC-antigen complex on a cell surface is crucial for activation of the adaptive immune response. This is because T cells can only recognize antigens that are presented in association with the MHC molecules on the surface of antigen-presenting cells. The MHC-antigen complex serves as a signal to activate T cells, which then orchestrate the immune response.

Question 14

A bone marrow transplant may not be appropriate from a given donor (Jane) to a given recipient (Jane's cousin Bob), even though Jane has previously given blood for one of Bob's needed transfusions, because ________.
A) Jane's major histocompatibility (MHC) proteins may not be a match
B) a blood-type match is less stringent than a match required for transplant because blood is more tolerant of change
C) Jane is heterozygous for MHC genes but Bob is not
D) Jane's MHC class II genes are not expressed in bone marrow
E) Bob's immune response is impaired

Accepted Answer

A bone marrow transplant requires a close match in the major histocompatibility complex (MHC) proteins, which play a key role in determining whether a recipient's immune system will recognize transplanted cells as self or non-self. While a blood type match is important for transfusions, it is less stringent than the match required for a bone marrow transplant. Additionally, the fact that Jane is heterozygous for MHC genes while Bob is not may create potential mismatches. The expression of MHC class II genes in bone marrow does not affect the match, as these genes typically play a role in presenting antigens to immune cells rather than directly affecting compatibility. The immune response of the recipient is also unrelated to the suitability of a particular donor.

Question 15

When antibodies bind antigens, the clumping of antigens results from ________.
A) the antibody having at least two binding regions
B) disulfide bridges between the antigens
C) a complement protein that makes the affected cells sticky
D) bonds between class I and class II MHC molecules
E) denaturation of the antibodies

Accepted Answer

Antibodies have at least two binding regions, allowing them to bind to multiple antigens at once and causing them to clump together. This is known as agglutination.

Question 16

Clonal selection is an explanation for how ________.
A) a single type of stem cell can produce both red blood cells and white blood cells
B) V, J, and C gene segments are rearranged
C) an antigen can provoke production of high levels of specific antibodies
D) HIV (human immunodeficiency virus) can disrupt the immune system
E) macrophages can recognize specific T cells and B cells

Accepted Answer

Clonal selection explains how specific antigens can trigger the production of high levels of antibodies by selecting and activating specific B cells that recognize the antigen. The selected B cells then undergo clonal expansion, producing a large number of identical cells that secrete the same antibody.

Question 17

The number of major histocompatibility (MHC) protein isoforms possible in a given human population is enormous. However, each individual has a limited array of MHC molecules because ________.
A) the MHC proteins are made from several different gene regions that are capable of rearranging in a number of ways
B) MHC proteins from one individual can only be of class I or class II
C) each of the MHC genes has a large number of alleles, but each individual inherits only two for each gene
D) once a B cell has matured in the bone marrow, it is limited to two MHC response categories
E) once a T cell has matured in the thymus, it can only respond to two MHC categories

Accepted Answer

Each individual inherits two alleles (one from each parent) for each of the MHC genes, which limits the array of possible MHC molecules. While MHC proteins are made from multiple gene regions that can rearrange, and there are different classes of MHC molecules, these factors alone do not explain why each individual has a limited array of MHC molecules.

Question 18

Immunological memory accounts for ________.
A) the human body's ability to distinguish self from nonself
B) the observation that some strains of the pathogen that causes dengue fever cause more severe disease than others
C) the ability of a helper T cell to signal B cells via cytokines
D) the ancient observation that someone who had recovered from the plague could safely care for those newly diseased
E) the ability of the immune system to present antigen fragments in association with major histocompatibility (MHC) antigens

Accepted Answer

Immunological memory is the ability of the immune system to remember and recognize a pathogen it has encountered before, leading to a faster and more effective response upon subsequent exposure. This phenomenon explains why someone who has recovered from the plague can safely care for others who are newly infected, as their immune system has developed memory cells that recognize and respond to the pathogen.

Question 19

The primary function of humoral immunity (humoral response) is to ________.
A) defend against fungi and protozoa
B) reject transplanted tissues
C) protect the body against cells that become cancerous
D) protect the body against extracellular pathogens
E) defend against bacteria and viruses that have already infected cells

Accepted Answer

Humoral immunity, also known as the antibody-mediated immunity, is responsible for defending the body against extracellular pathogens such as bacteria and viruses that have not yet infected cells. This type of immunity relies on the production of specific antibodies that can neutralize the pathogen and tag it for destruction by immune cells.

Question 20

If a patient is missing B and T cells, what would be absent from the immune response?
A) memory
B) lysozymes
C) cytokines
D) defense against bacteria
E) the innate immune response

Accepted Answer

The answer of If a patient is missing B and...

Quiz 48: The Immune System in Animals

The cell-mediated immunity that destroys virally infected cells primarily involves ________.

A function of antibodies is to ________.

For the successful development of a vaccine to be used against a pathogen, it is necessary that ________.

Which of the following cells are involved in cell-mediated immunity and also respond to class I MHC molecule-antigen complexes?

Which of the following is a difference between class I and class II major histocompatibility complex (MHC) proteins?

Which of the following is a difference between B cells and T cells?

Phagocytosis of microbes by macrophages is enhanced by ________. I. the binding of antibodies to the surface of microbes II. antibody-mediated agglutination of microbes III. the release of cytokines by activated B cells

Secondary immune responses upon a second exposure to a pathogen are due to the activation of ________.

A cell type that interacts with both the humoral and cell-mediated immune pathways is a ________.

Why might humans need yearly vaccination for influenza?

Which of the following is crucial to activation of the adaptive immune response?

A bone marrow transplant may not be appropriate from a given donor (Jane) to a given recipient (Jane's cousin Bob) , even though Jane has previously given blood for one of Bob's needed transfusions, because ________.

When antibodies bind antigens, the clumping of antigens results from ________.

Clonal selection is an explanation for how ________.

The number of major histocompatibility (MHC) protein isoforms possible in a given human population is enormous. However, each individual has a limited array of MHC molecules because ________.

Immunological memory accounts for ________.

The primary function of humoral immunity (humoral response) is to ________.

If a patient is missing B and T cells, what would be absent from the immune response?