Question 1

The selection and differentiation of B cells during clonal selection occurs by which cellular process?

Accepted Answer

The selection and differentiation of B cells during clonal selection occurs by mitosis. As the B cells are activated and undergo clonal expansion, they differentiate into plasma cells, which are responsible for producing antibodies, or memory B cells, which provide long-term immunity. This process involves mitosis, as the parent B cell divides to produce identical daughter cells with the same genetic information. Meiosis, binary fission, and cytokinesis are not involved in the selection and differentiation of B cells during clonal selection.

Question 2

Which of the following cells are involved in cell-mediated immunity?

Accepted Answer

Cytotoxic T cells are a type of T cell that directly kills infected or cancerous cells through the release of toxic molecules. This is a key component of cell-mediated immunity, which targets abnormal or infected cells specifically. Memory B cells are involved in antibody-mediated immunity, while macrophages and natural killer cells have roles in both types of immunity but are not specifically involved in cell-mediated immunity.

Question 3

Which of the following class of immunoglobulin proteins is associated with allergies?

Accepted Answer

IgE is the class of immunoglobulin proteins associated with allergies. When a person is exposed to an allergen, such as pollen or pet dander, their immune system produces IgE antibodies which then bind to mast cells and basophils in the body. Upon subsequent exposure to the allergen, the IgE-bound mast cells and basophils release histamine and other inflammatory mediators, leading to the symptoms of an allergic reaction.

Question 4

Given the B cell's role in the adaptive immune response, it is reasonable to assume that a B cell has:

Accepted Answer

B cells are primarily responsible for the production of antibodies, a process that requires the synthesis of proteins. This synthesis occurs in the rough endoplasmic reticulum (rough ER), which is why B cells have extensive rough ER to accommodate the high demand for protein production.

Question 5

You are a doctor examining a patient's blood-test results. The patient's T cell count is low. You examine scans of the patient's thymus. It is underdeveloped, which means the T cells in the blood will:

Accepted Answer

The answer of You are a doctor examining a patient's...

Question 6

Clonal selection results in the formation of:

Accepted Answer

Clonal selection results in the formation of both plasma cells and memory cells, which are responsible for the production of secreted antibody. Therefore, all of these choices are correct.

Question 7

One of the major advances in transplant surgery over the last 50 years is the use of immunosuppressant drugs to reduce the response of the immune system to the transplanted organ. Based on what you know about the immune system, what cells do you think these drugs act on?

Accepted Answer

Immunosuppressant drugs are specifically designed to act on T cells, which are a key component of the adaptive immune response responsible for recognizing and attacking foreign tissues in the body. By suppressing the activity of T cells, these drugs help prevent rejection of transplanted organs. While other cells and components of the immune system (such as B cells and phagocytes) also play important roles in immune responses, they are not the primary target of immunosuppressive drugs in transplant surgery.

Question 8

What determines the specificity of the hypervariable region of an antibody?

Accepted Answer

The specificity of the hypervariable region of an antibody is determined by genomic rearrangement. The genes that encode for the variable regions of the light and heavy chains of antibodies can recombine in different ways during the development of B cells, leading to a diverse repertoire of antibodies with different specificities. This process is known as V(D)J recombination and plays a crucial role in generating the antigen-binding diversity of antibodies. The hypervariable regions of the antibody are also known as complementarity-determining regions (CDRs) due to their close association with the paratope, which is the part of the antibody that interacts with the antigen.

Question 9

Clonal selection is a process in which:

Accepted Answer

Clonal selection refers to the process where an antigen binds to a specific B cell receptor, leading to the proliferation (mitotic cell division) of that B cell to produce clones that secrete the specific antibody.

Question 10

Antibody diversity is primarily the result of:

Accepted Answer

Antibody diversity is primarily the result of genomic rearrangement, which involves the recombination of V (variable), D (diversity), and J (joining) gene segments during B cell development. This process creates a vast array of potential antibody variable region sequences, leading to the generation of diverse antibodies capable of recognizing and binding to a wide range of antigens. mRNA splicing, differential gene expression, and gene silencing also play important roles in regulating antibody diversity, but they are not primary drivers of the process.

Question 11

Which cell type is responsible for the strength of the secondary immune response?

Accepted Answer

Memory cells are responsible for the strength of the secondary immune response because they are formed during the primary immune response and "remember" the antigen. When the same antigen is encountered again, memory cells quickly differentiate into plasma cells and produce the necessary antibodies to eliminate the pathogen. Naive B cells and plasma cells do play a role in the immune response, but they do not contribute to the strength of the secondary response in the same way that memory cells do.

Question 12

When organs are transplanted from one individual to another, they can be attacked by cells of the host's immune system and rejected. Sometimes, the opposite occurs, in which the transplant (the graft) attacks the host. This is called graft-versus-host disease, and is MOST common in which of the following types of transplants?

Accepted Answer

Graft-versus-host disease is most commonly seen in bone marrow transplants, where the transplanted bone marrow cells (graft) can attack the host's cells.

Question 13

The interaction between an antibody and its antigen is most similar to which of the following?

Accepted Answer

A receptor and its ligand is the most similar interaction to an antibody and its antigen because both involve specificity and recognition between two molecules, leading to a specific biological response. Enzyme and substrate interaction involve catalysis and change in substrate structure, while codon and anticodon interaction occurs during protein synthesis and involve base-pairing between nucleotides. Motor protein and cytoskeletal filament interaction involve movement and transport within the cell.

Question 14

A new technique to replace diseased organs is harvesting stem cells from the patient's own body and using them to grow a new organ that is then transplanted into the body. In this case:

Accepted Answer

Since the new organ is grown from the patient's own stem cells, there should be no immune response or rejection. This is known as an autologous transplant. Immmunosuppressant drugs are not necessary in this case. Antibodies and antigens would also not be generated since the organ is from the patient's own body.

Question 15

How does a vaccination help to prevent a disease?

Accepted Answer

When a vaccine is administered, it stimulates the immune system to produce a population of memory cells that recognize and respond quickly to the specific pathogen in question. This means that if the person is exposed to the actual infection later on, their body will be able to mount a strong and quick response, preventing the disease from taking hold or reducing the severity of symptoms.

Question 16

You are a doctor examining a patient's blood test reports. You are looking at the ratio of helper T cells to cytotoxic T cells. Helper T cells _____; cytotoxic T cells _____. You can tell them apart by the type of protein they _____.

Accepted Answer

Helper T cells activate other immune system cells, while cytotoxic T cells kill altered host cells. These cells can be distinguished by the type of protein they express on their plasma membrane.

Question 17

Diseased organs can sometimes be replaced by healthy organs from donors. A long-standing problem with organ transplants is rejection of the organ by the recipient. Rejection would not be expected if the transplanted organ came from a(n):

Accepted Answer

Identical (monozygotic) twins have the same genetic makeup, which includes the human leukocyte antigens (HLA) that are responsible for initiating immune responses. Therefore, their immune systems should not recognize the transplanted organ as foreign and reject it. The other choices may have some similarities but could still differ in their HLA types, leading to a higher risk of rejection.

Question 18

You are a doctor examining a patient's blood-test results. The patient's T cell count is low. You are concerned that the patient will:

Accepted Answer

T cells are important for killing infected host cells and helping to activate other immune cells. If the T cell count is low, it means the patient will have a reduced ability to kill infected host cells if they become infected with a virus or intracellular bacteria.

Question 19

Sometimes an organ can be replaced by moving it from one part of the body to another. This can be done, for example, to replace damaged skin or joints. In these cases:

Accepted Answer

When an organ or tissue is moved from one part of the body to another in the same individual (autograft), rejection is not expected because the transplanted tissue is genetically identical to the recipient, thus not triggering an immune response.

Question 20

You are a doctor who examines a swollen and warm puncture wound on the hand of a patient. Does the fact that the patient's immune system responded normally to this wound tell you that every aspect of his or her immune system is functioning normally?

Accepted Answer

The response to a puncture wound does not include the complement response or adaptive immune response.

Quiz 43: Animal Immune Systems