Question 1

Macrophages and dendritic cells are

Accepted Answer

Macrophages and dendritic cells are both types of antigen-presenting cells, which means they are responsible for presenting foreign substances (antigens) to T cells and B cells to initiate an immune response. They do not produce antibodies themselves, but they do play a crucial role in activating antibody-producing cells.

Question 2

The immune response is directed against an entire molecule.

Accepted Answer

The immune response can be directed against specific parts of a molecule, known as epitopes or antigenic determinants, rather than the entire molecule.

Question 3

Memory cells may take the form of

Accepted Answer

Memory cells can take the form of B cells, T cytotoxic cells, and T helper cells. All of these choices are correct. Memory cells are formed during an initial immune response and allow for a quicker and more robust response upon subsequent exposure to the same antigen.

Question 4

The peptides presented by MHC class II peptide molecules are

Accepted Answer

MHC class II peptide molecules present exogenous antigens, which are antigens that come from outside the cell and are taken up and processed by antigen presenting cells.

Question 5

The surface receptors on B and T cells both

Accepted Answer

Surface receptors on B and T cells, also known as B cell receptors (BCRs) and T cell receptors (TCRs), respectively, both have variable and constant regions that allow them to recognize and bind to specific antigens. However, their roles in each type of cell are different. BCRs are responsible for recognizing and binding to antigens directly, while TCRs can only recognize antigens that are presented to them by other cells. Therefore, choice D is the best answer.

Question 6

Giant cells are

Accepted Answer

Giant cells are formed by the fusion of macrophages in order to contain and destroy bacterial infections.

Question 7

It would be useful if antigens were delivered directly to

Accepted Answer

Peyer's patches and M cells are both involved in the immune response in the gut. Peyer's patches are areas of aggregated lymphoid tissue in the small intestine, which play a role in the immune surveillance of intestinal bacteria. M cells are specialized cells that transport antigens from the gut lumen to immune cells in Peyer's patches, facilitating the initiation of an immune response. Therefore, delivering antigens directly to both Peyer's patches and M cells would be useful for stimulating an immune response.

Question 8

Apoptosis

Accepted Answer

Apoptosis is a form of programmed cell death that is often referred to as cell suicide. It can be induced in target cells by effector T cytotoxic cells. Therefore, both options A and B are correct, making E the best choice. Option C is incorrect as apoptosis does not refer to T cell death. Option D is incorrect as it refers to the transformation of B cells into plasma cells, which is not related to apoptosis.

Question 9

Antigens may be processed for presentation by

Accepted Answer

Antigens can be processed and presented by both macrophages and dendritic cells. Erythrocytes and T cytotoxic cells do not have this capability.

Question 10

T-independent antigens

Accepted Answer

T-independent antigens include polysaccharides.

Question 11

Antibody and antigen are held to one another by covalent bonds.

Accepted Answer

Antibody and antigen bind to each other through non-covalent interactions such as hydrogen bonding, electrostatic interactions, and Van der Waals forces.

Question 12

Class II MHC molecules are found primarily on

Accepted Answer

Class II MHC molecules are primarily found on antigen-presenting cells, such as macrophages and dendritic cells, which play a critical role in presenting antigens to T helper cells. Erythrocytes and T cytotoxic cells do not typically present antigens and therefore do not express Class II MHC molecules on their surfaces.

Question 13

Substances with a molecular weight of less than 10,000 Daltons make good antigens.

Accepted Answer

Substances with a molecular weight of less than 10,000 Daltons are generally considered too small to elicit a strong immune response on their own and are often referred to as haptens rather than good antigens.

Question 14

Antibody molecules are very rigid in structure.

Accepted Answer

Antibody molecules are flexible in structure, allowing them to bind to a wide range of antigens.

Question 15

The stimulation of B cells to divide and mature is provided by

Accepted Answer

T helper cells provide signals to activate B cells to divide and mature into antibody-secreting plasma cells.

Question 16

Which is involved in reacting to virus-infected cells?

Accepted Answer

Reacting to virus-infected cells involves cell-mediated immunity, which is mediated by T cytotoxic cells that directly kill infected cells. The recognition of infected cells by T cells is facilitated by the presentation of viral antigens on the surface of cells through the MHC I complex. Therefore, all choices (A, B, D) are involved in reacting to virus-infected cells, but the most comprehensive answer is E, which includes all the above components. Choice C (B cells) is not directly involved in reacting to virus-infected cells.

Question 17

All antigens are immunogens.

Accepted Answer

While all immunogens are antigens, not all antigens are necessarily immunogens. Antigens are any substance that can be recognized by the immune system and elicit an immune response, while immunogens are antigens that are capable of inducing an immune response.

Question 18

Only antigen-presenting cells

Accepted Answer

Only antigen-presenting cells such as dendritic cells, macrophages, and B cells produce MHC class II molecules, which are necessary for presenting antigens to helper T cells and initiating the adaptive immune response. Antigen-presenting cells do not directly produce antibodies or activate cytotoxic T cells, but instead play a crucial role in initiating and coordinating the adaptive immune response.

Question 19

Perforin is produced by

Accepted Answer

Perforin is produced by NK cells.

Question 20

CD8 cells are often

Accepted Answer

CD8 cells, also known as cytotoxic T cells, are responsible for killing virus-infected or cancerous cells. They do not function as T helper or suppressor cells, nor do they cause hypersensitivity reactions.

Quiz 15: The Adaptive Immune Response