Deck 27: Innate Defences and the Immune System

Question 1

The role of the immune system is to

A) secrete enzymes that destroy microorganisms.
B) provide protection from pathogens such as viruses and bacteria.
C) produce natural antibiotics.
D) respond to parasite invasion and establish symbiosis.
E) All of the above are true.

Answer 1

provide protection from pathogens such as viruses and bacteria.

Question 2

Which of the following statements is false?

A) Antibodies are the result of random genetic rearrangement.
B) Antibodies provide non-specific immunoprotection.
C) Antibodies are protein molecules.
D) Antibodies are the basis of acquired immunity.
E) Antibodies are produced by lymphocytes.

Answer 2

Antibodies provide non-specific immunoprotection.

Question 3

An antibody is best described as

A) glycoprotein produced in a cellular response to an immunogen.
B) protein molecule produced only by plasma cells in response to an antigen and which reacts specifically with that antigen.
C) the actual portion of an antigenic molecule that is recognised by a receptor.
D) glycoprotein molecule produced by B lymphocytes and plasma cells, in response to an immunogen.
E) a fundamentally important response to a pathogen found at all levels of animal life.

Answer 3

glycoprotein molecule produced by B lymphocytes and plasma cells, in response to an immunogen.

Question 4

In the human immune system, the consequences of the activation of the complement cascade include

A) resistance to viral infection.
B) autoimmunity.
C) local inflammation, phagocytosis and bacterial lysis.
D) production of antigenic peptides.
E) establishment of acquired resistance.

Question 5

An epitope is best defined as

A) the actual portion of an antigenic molecule that is recognised by a receptor.
B) an antigen which precipitates an immune response by inducing the production of antibodies or T-cell receptors.
C) any molecule which can be recognised by one of the specific molecules of the immune system.
D) the interacting protein in the complement cascade.
E) an immunogen.

Question 6

A form of non-specific defence against infection is

A) the complement system.
B) interferons.
C) lysozymes.
D) cytokines.
E) All of the answers are forms of non-specific defence against infection.

Question 7

Interferons

A) facilitate chemotaxis, opsonisation and lysis.
B) are glycoproteins produced by T lymphocytes in response to viral infections.
C) interfere with virus replication and production of viral proteins.
D) are part of the complement system.
E) are part of the innate response to bacterial infection.

Question 8

A primary response to infection in the mammalian immune system

A) occurs on contact with a virus after immunisation.
B) happens once in the lifetime of an animal.
C) is not 'remembered' by the immune system.
D) occurs after first exposure to an antigen.
E) involves the complement cascade.

Question 9

A secondary immunological response is

A) generally slower and smaller than a primary response.
B) dependent on an immunological memory.
C) mounted against any type of pathogen so long as the immune system has previously mounted a primary response against any other pathogen.
D) dependent on the primary response activating the complement cascade.
E) absolutely specific. A secondary response cannot be mounted unless a primary response has already been elicited by the exact pathogen.

Question 10

The capacity of immune systems to protect against pathogens

A) is a consequence of a small number of inherited genetic elements which are randomly rearranged during differentiation of specific immune cells.
B) is a consequence of a very large number of inherited genetic elements which produce individual lymphocytes carrying a distinct antigen receptor.
C) depends on mounting an inflammatory response at the site of infection.
D) is principally a function of the physical and chemical barriers and the action of phagocytic cells in conjunction with the complement system which prevent pathogens from becoming established.
E) depends on the effective screening of lymphocytes in the thymus, spleen and bone marrow to prevent the release of cells with receptors which can bind with molecules on the surfaces of self cells as if they were antigens.

Question 11

The theory of clonal selection in immune responses suggests that

A) cells interacting with antigens will proliferate.
B) infants receive their immune-specific lymphocytes from their mother.
C) the pre-immune response produces a large number of genetically identical lymphocytes.
D) lymphocytes will rearrange their surface molecules.
E) clones of cells expressing the TCR (T-cell receptor) will multiply and interact with an organism to kill it.

Question 12

During an immune response any lymphocyte that encounters its specific antigen

A) binds with it precipitating a series of complex rearrangement events involving variable (V) genes, diversity (D) and joining (J) elements but not constant (C) genes.
B) undergoes a series of complex rearrangement events involving variable (V) and constant (C) genes together with diversity (D) and joining (J) elements.
C) will not bind with it in the absence of complement proteins failing to opsonise the pathogen.
D) will secrete antibodies specific to the antigen and neutralise it.
E) will undergo clonal selection.

Question 13

Immune responses to pathogens include the

A) production of lysozymes in tears and saliva.
B) production of mucus in the respiratory and genital tracts.
C) production of immunoglobulins.
D) lowering of the pH in the stomach.
E) activation of the complement cascade.

Question 14

A humoral immune response

A) is mediated by soluble lymphokine molecules released by B cells into the serum or other body fluids.
B) is invoked principally in response to intracellular or viral infections.
C) depends on antibodies bound to cell membranes of B memory cells and B plasma cells.
D) is most effective against extracellular phases of bacterial and viral infections.
E) is induced against intracellular parasitic infections.

Question 15

T lymphocytes

A) mature in the spleen and if the spleen is absent or removed early in fetal development no T cells are produced and profound immunodeficiency results.
B) fall into two functionally distinct classes, helper cells and cytotoxic cells, which secrete lymphokines.
C) have TCR (T-cell receptors) which are functional only when bound to the membranes of helper cells and cytotoxic cells.
D) are essential to primary immunity.
E) are screened in the spleen but mature in the bone marrow.

Question 16

Phagocytes

A) are of two main types: mononuclear phagocytes such as granulocytes, and polymorphs such as macrophages.
B) include monocytes found principally in tissues, rather than circulating in blood.
C) include the polymorphonuclear granulocytes and macrophages.
D) include dendritic cells that are confined to strategic locations in the lymphatic system such as the Kupffer cells of the liver which can present antigens to T and B cells.
E) are specific effector cells which engulf bacteria in response to secondary infection.

Question 17

In the human immune system

A) an immunogen is the variable region of an immunoglobulin molecule.
B) an immunogen is an antigen which stimulates lymphocytes to make an immune response.
C) antibodies will respond to polypeptide fragments of three or more amino acids.
D) epitopes are produced during an autoimmune response.
E) immunological memory results from activation of specific epitopes produced in response to infection.

Question 18

An antigen is best defined as

A) a foreign organic molecule recognised and bound by T-cell receptors or antibodies.
B) the actual portion of a molecule which elicits a specific immune response.
C) an immunogen.
D) a membrane protein of a bacterium which interacts with a B-cell to cause lysis.
E) any molecule which can be recognised by one of the specific molecules of the immune system.

Question 19

Immunogens

A) are peptides of up to ten amino acids, which are the largest molecules capable of binding directly with TCRs or antibodies.
B) are capable of being bound by antibodies directly without the mediation of major histocompatibility (MHC) proteins.
C) are recognised by TCRs only when presented complexed with the MHC molecules of phagocytes. The MHC molecules are only capable of presenting epitopes that were on the surface of the intact molecule.
D) to which T cells respond are of a wide variety and include carbohydrates and proteins. B cells only respond to protein immunogens.
E) are antibodies produced in response to a foreign organism.

Question 20

In the human immune system, each antibody molecule consists of four polypeptide chains. Which of the following statements about these chains is CORRECT?

A) There are two identical heavy and two identical light chains.
B) Each chain has two different binding sites at its end.
C) Only the heavy chains have a variable region.
D) Epitopes are attached to the ends of the chains.
E) The antigen binding site is formed by the dimerisation of an $\alpha$ and a $\beta$ chain polypeptide.

Question 21

In the human immune system, a difference between T-cell receptors and immunoglobulins is that T-cell receptors have

A) twice as many binding sites.
B) more subtypes.
C) a larger degree of polymerisation.
D) only two polypeptide chains.
E) four polypeptide chains.

Question 22

Which of the following statements about the major histocompatibility complex (MHC) is true?

A) MHC molecules are expressed on professional antigen-presenting cells such as dendritic cells, macrophages and B cells.
B) MHC molecules do not influence the production of immunoglobulins although they must bind antigens before TCRs will recognise the antigen.
C) MHC molecules are expressed only on activated T-cells to enable recognition of specific antigens.
D) MHC molecules are coded for by the multigene complex, which is located with the variable (V) genes and joining (J) elements rather than the constant (C) gene or diversity (D) elements.
E) The MHC restriction concept is particularly important in modern immunology because it details the categories of antigens capable of binding to MHC molecules.

Question 23

Immunological tolerance

A) describes the response mounted against a pathogen where an immunological memory already exists.
B) precipitates an autoimmune response with debilitating consequences and is dysfunctional.
C) is best treated with anti-inflammatory or immunosuppressive drugs rather than antihistamines.
D) occurs in mature lymphocytes where interaction with self antigens causes cellular damage resulting in disease.
E) develops at an early stage and is critical to the effective operation of a normal immune system.

Question 24

The immune system

A) includes secondary lymphoid organs such as Peyer's patches and the adenoids.
B) mounts the strongest immune response at the site of infection although the cells, debris and antigens from this site are eventually carried by the lymphatic vessels to the local lymph nodes where they are simply filtered.
C) mounts immune responses at primary lymphoid organs such as the lymph nodes, spleen and tonsils.
D) is dependent on lymphatic vessels to filter out foreign organisms and co-ordinate an organised response involving T-cells.
E) has secondary lymphoidal tissue that is recruited to an immune response only where an immune memory already exists as a result of a previous or primary infection.

Question 25

Allergenic responses occur because of:

A) infection through the epithelial surfaces.
B) IgE binding to the surface of mast cells.
C) proliferation of TC cells.
D) the cascade of the complement system.
E) activation of B cells by antigen, inducing secretion of antibodies and histamines.

Question 26

Which of the following statements is INCORRECT?

A) Viruses grow within cells and each type of virus grows in only certain types of cells.
B) The role of antibodies and T cells varies on the type of disease and stage of infection.
C) Viruses are more easily controlled by the immune system than bacteria.
D) AIDS results in a drastic drop in T cells.
E) Fungal infections are controlled by T cell responses which leads to the development of resistance.

Question 27

Most fatal cancerous tumours are allowed to grow because

A) the individual's immune system is not functioning properly.
B) they contain cells that are recognised as foreign by the immune system.
C) the immune system did not evolve to protect against tumours.
D) the cells are not immunogenic as they are recognised as self.
E) although tumours are immunogenic, they mainly occur in tissues and so are not accessible to lysis by T_C cells.

Question 28

Which of the following statements about immunity in animals is INCORRECT?

A) Invertebrates have no lymphocytes or truly specific immune responses.
B) Only vertebrates possess phagocytic cells.
C) Some invertebrates have antisomes that can distinguish its own cells from foreign material.
D) Most vertebrates have an immune system with antibodies, a spleen, thymus and T and B cells.
E) Multicellular invertebrates contain phagocytic cells that are able to engulf foreign material.

Question 29

In plants

A) immune defence is similar to that of invertebrates.
B) some species resemble mammals by having molecules coded by specific genes to be able to recognise particular pathogens.
C) immune mechanisms are local.
D) a circulatory system enables immune defence.
E) only the cell wall provides protection from invasion.

Question 30

Complement is

A) a series of about 20 proteins in mammals which interact to lyse membranes of some organisms.
B) a form of self-recognition which helps distinguish self from non-self.
C) a major arm of the defence mechanism of Chordates.
D) central to a specific immune response due to their ability to cause antibody production.
E) a transmembrane protein which is a primitive recognition molecule which when stimulated secretes defence peptides.

Question 31

Evolution of the immune system has resulted in a wide array of mechanisms of increasing complexity. Which of the following statements about the immune system is INCORRECT?

A) Sea squids have small lymphocytes similar to those in mammals.
B) Some invertebrates produce antibody-like proteins which attach to non-self and aid clearance of the foreign material.
C) Birds have all the characteristics and functions of the immune system that mammals have.
D) The major secretory antigen IgA, which protects mucous membranes, is produced only in mammals.
E) Macrophages developed late in evolution, with fully active macrophages being found only in vertebrates.

Question 32

T-cell receptors (TCR) and Immunoglobulins (Ig) are glycoproteins that recognise specific antigens. Their structure and function is similar for both EXCEPT

A) they are dimers of two different polypeptides
B) they are synthesised by the rearrangement of several, similar gene segments.
C) they are composed of a variable epitope that contributes to the antigen binding site.
D) they interact with antigen to produce proliferation and differentiation of T-cells.
E) they are membrane-bound molecules on the surface of the lymphocyte.

Question 33

Innate defence mechanisms are

A) only relevant to lower organisms as the immune system of mammals has superseded the primitive response.
B) the rapid first line of defence against infections in mammals.
C) specific, distinguishing clearly between different organisms.
D) important in early infection, but decrease once the specific acquired immunity is developed.
E) always present, and may be activated if the infection is large.

Question 34

If a pathogen passes the initial external defences and invades the body

A) internal specific defence mechanisms are activated.
B) interleukin-2 is produced by natural killer cells to expand the initial response.
C) monocytes release perforins which punch holes in the membranes of infected cells.
D) phagocytic cells engulf particles and kill the invading organisms.
E) macrophages are attracted to the site of infection and activate the complement cascade.

Question 35

Complement is

A) produced by macrophages in response to activation by an invading pathogen.
B) a cytokine which induces local inflammation increasing vascular permeabiligy at the site of infection.
C) part of the innate defences activated by the invading pathogen.
D) a key part of immunological memory.
E) a serum protein that exists in the fluids of the body in an inactive state.

Question 36

Dendritic cells are

A) the central cells of acquired immunity which specifically recognise different antigens.
B) non-specific effector cells which engulf and kill bacterial cells.
C) kill virus infected cells but not normal cells.
D) antigen-presenting cells which engulf and process antigen fragments of invading organisms.
E) cells which recognise antigen receptors anchored in their membranes.

Question 37

A fundamental requirement of any immune defence system is its ability to distinguish between _______ and ________.

A) antibodies; antigens.
B) bacteria; viruses.
C) internal; external.
D) self; non-self.
E) erythrocytes; leukocytes.

Question 38

An organism that has a reduced or absent ability to detect and respond to pathogen-associated molecular patterns most likely has a deficiency in.

A) phagocytosis.
B) activation of globular proteins.
C) induction of parathyroid hormone.
D) phosphorylation.
E) toll-like receptors.

Question 39

Why are immune responses mediated by antibodies referred to as 'humoral immunity'?

A) Because it is mediated by the humos
B) Because it involves H-cell recognition of foreign cells
C) Because they take place in the blood or humors
D) There is no such thing as humoral immunity
E) Because humoral is akin to holistic, denoting a systemic immune response which is uniform to all antibody responses

Question 40

A scientist wants to create new dendrites in vitro. In order to do this, what would be the most differentiated cell he could use to create dendrites and where would he harvest them from?

A) Myeloid progenitors from bone marrow
B) Lymphoid progenitors from the thymus
C) Multipotent progenitors from bone marrow
D) Lymphoid progenitors from bone marrow
E) Myeloid progenitors from the thymus

Question 41

Which cell of the immune system has similar morphology to classical lymphocytes, but lacks the same specificity?

A) B lymphocyte
B) Natural Killer (NT) cells
C) T cell
D) Monocyte
E) Granulocyte

Question 42

Which immune cell regulates the activation of the killing capacity of macrophages?

A) Plasma cell
B) Granulocyte
C) NK cells
D) T-cells
E) B lymphocytes

Question 43

When an immature T-cell enters the thymus, there is a rearrangement of genes coding for the T-cell receptor. What immune protein produced by B lymphocytes undergoes an analogous development?

A) alpha-amylase.
B) beta-glucanase.
C) Phenylalanine lyase.
D) Major histocompatibility complex.
E) Immunoglobulin.

Question 44

A sample of helper cells (T_H) is being studied in the laboratory. When scientists present them with antigen in an attempt to stimulate the development of other immune system cells there is no affect. Why would this be?

A) T_C cells have not been processed in the thymus.
B) Macrophages lack a functional receptor.
C) The antigens have not been properly processed.
D) There are no antibodies present.
E) B cells have no activation binding site.

Question 45

In what organ to B cells develop in birds?

A) Bone marrow
B) Brain
C) Brique de loopus
D) Bursa of Fabricius
E) Basal ganglion