Question

Question 11 pts

which of the following events turns on/activates T and B cells?  

Group of answer choices

fever

T and B cells bind to the antigen (epitope) that they recognize

Release of type-1 interferons

antibodies bind to T and B cells

complement activation

Question 21 pts

under NORMAL circumstances, which of the following is NOT an antigen (or not likely to be an antigen)?

Group of answer choices

molecules bound by TCR

molecules bound by soluble antibodies and BCR

viral or bacterial components

host/self molecules

molecules that the immune system (T and B cells) can recognize, bind and respond to

Question 31 pts

which of the following does NOT describe an antibody molecule:

Group of answer choices

is made by a B cell

has two antigen-binding sites

can bind to 2 different antigens/epitopes at once

Its stem (Fc region) can activate complement or stimulate cells of the innate defences to respond (e.g.,damage eukaryotic pathogens or do phagocytosis)

binds to ONE specific antigen/epitope/microbe

Question 41 pts

opsonization:

Group of answer choices

is something that ANTI-BIOTICS (instead of anti-bodies) do to bacteria to control or eliminate them

helps/facilitates phagocytosis

is something done by anti-BODIES (immunoglobulins) only

is defined as preventing microbes or toxins from attaching to our cells

is NOT done by complement

Question 51 pts

the class-2 pathway of antigen presentation is used for:  

Group of answer choices

displaying antigen so CD4 T cell can bind it

used for displaying “endogenous” antigens

displaying components of microbes that live or replicate inside an infected cell (i.e., in the cytosol)

displaying antigen so CD8 T cell can bind it

displaying antigen so dendritic cells can bind it

displaying antigen so B cells can bind it

Question 61 pts

which of the following is a role of the lymphatic system:

Group of answer choices

transports type-1 interferons to site of infection

transports complement to site of infection

causes the symptoms and signs of inflammation (such as redness and swelling)

brings microbes/antigens into contact with T and B cells

Question 71 pts

the differential white blood cell count:

Group of answer choices

Refers ONLY to the number of T cells and B cells in the blood

is the relative numbers of memory cells and effector cells in the blood

does NOT change during the course of infection

includes the amount of complement proteins in the blood

can give us an idea of the patient’s condition during an infection

Question 81 pts

A B-cell that recognizes the spike of covid-19 virus/sars-cov-2 makes antibodies that bind:

Group of answer choices

any protein component of covid-19 virus, not just the spike

the RNA polymerase of the covid-19 virus

the RNA polymerase of any RNA virus

the spike of the flu virus only

spike of the covid-19 virus only

Question 91 pts

T and B cells are active/functional ALL the TIME, even when there is no infection nor exposure to microbe that T or B cells recognize

Group of answer choices

True

False

Question 101 pts

worms and eukaryotic pathogens are mainly controlled by:   

Group of answer choices

phagocytosis

the humoral immune response ONLY

cytotoxic T cells (CTL)

cytokines & enzymes from Th/T helper cells

Type 1 interferons and inflammation

antibodies and cells of the innate defences (ADCC)

Question 111 pts

A CTL/activated CD8T cell that recognizes the replicase enzyme of the hepatitis b virus can destroy:

Group of answer choices

cells of the body infected by any pathogen

cells of the body infected by covid-19

cells of the body infected hepatitis b virus that is presenting epitopes of the replicase enzyme

B cell displaying hepatitis b replicase epitope by the class-2 pathway

uninfected cells of the body

cells of the body infected by hepatitis b that is presenting epitopes of the heptatitis b spike protein ONLY

Question 121 pts

which antigen is mostly likely to be displayed by the class-1 pathway of antigen presentation?

Group of answer choices

viral proteins made inside infected cell

bacterial exo-enzyme

components of microbe that has entered the antigen presenting cell via a vesicle (i.e., entered the cell via endocytosis)

components of bacteria found in body fluids or extracellular space

bacterial exo-toxin

Question 131 pts

Infection by the flu virus turns on:

Group of answer choices

only T and B cells that recognize the flu virus

all T and B cells that recognize viruses (not just ones that recognize the flu virus)

all T cells only

all B cells only

all T cells and B cells

Innate defences only, not the immune system

Question 141 pts

“activated” (functional) T or B cells that respond to (or “attack”) microbe/antigen during a FUTURE re-exposure to the microbe are called___. These cells are generated during_____,

(for each choice: the item before the semicolon goes into the first space; item after the semicolon goes into the 2nd space.)

Group of answer choices

antigen presenting cells; antigen presentation

phagocytes; inflammation

mast cells; allergies

memory cells; T or B cell activation

effector cells; T or B cell activation

Question 151 pts

B cell activation requires:

Group of answer choices

signals from CD8 T cells (CTL)

signals from CD4 T/Th cells

B cell binding to antigen

B cell binding to antigen and signals from CD4 T/Th cells

B cell making physical contact with Dendritic cells

Question 161 pts

the following should occur when the immune system is re-exposed to a microbe it encountered in the past:

Group of answer choices

B cells should release higher amounts of antibodies and CTLs should kill more infected cells

the amount of antibodies decline very rapidly-within 2 weeks after re-exposure to microbe

the T and B cells that recognize the microbe are turned on more slowly

memory cells are not binding/responding to microbe

Th cells should release lower amounts of cytokines than during the primary response

Question 171 pts

what is the role of IgE (E class antibodies):

Group of answer choices

“all-purpose” antibody

protects us during the early part of an infection

prevent microbes from infecting mucus membranes

fighting off worms or other eukaryotic pathogens

Question 181 pts

An antibiotic can be used as a drug:  

Group of answer choices

when it’s shown to have selective toxicity

as soon as it’s discovered

when it is proven NOT to cause resistance in bacteria

when your instructor says so

when people figure out a way to modify it so that bacteria cannot overcome them

Question 191 pts

one reason that secondary/memory responses are stronger than primary responses is because there are more cells that recognize and respond to the antigen/microbe in a secondary response

Group of answer choices

True

False

Question 201 pts

what is the advantage of using broad-spectrum antibiotics?

Group of answer choices

controls spread of resistance by wiping out resistant bacteria

they specifically kill pathogenic bacteria

keep patients alive until pathogen is identified

they are also effective against diseases caused by viruses

helps to maintain normal flora population

Answer 1

1) The B-cells and the T-cells both originate in the bone marrow, but the T-cells migrate to the thymus for differentiation while the B-cells continue to remain in the bone marrow for differentiation. Both T-cells and B-cells require antigens to trigger them into action but they respond differently. B-cells require two distinct signals to become activated, and results in B-cell differentiation into plasma cells or memory cells. The first activation occurs when antigen binds to B cells receptors (BRCs) which is followed by receptor-mediated endocytosis, digested and complexed with MHC class II molecules on B-cell surface. The second activation requires the interaction of B cell with helper T cells, where MHC class II present a population of cells known as antigen presenting cells (APCs) to T cells. When the peptide fragments to MHC is fused and inserted into the plasma membrane, it triggers T cell activation or B cell activation. B cells evolve into plasma cells under the influence of T cell released cytokines while other B cells circulate as memory cells. Plasma cells secrete antibodies in greater amounts, whereas B memory cells live for months or years, and are part of the immune memory system. So option (b) is the correct answer.

2) Antigen are foreign molecules that invade the body of an organism. They stimulate the production of antibodies in response to infection. Antigens are generally large molecules amd majority of them are made of proteins or polysaccharides found on the cell walls of bacteria and other cells or on the coats of viruses. T cell receptors (TCR) on helper T cells bind to the antigen complexed MHC class II molecules on B cell surface resulting its activation. The molecules bound by soluble antibodies produced by plasma cell of B lymphocytes and B cell receptors (BRCs) are also antigen. So basically, antigen are molecules that the immune system (B and T cell) can recognize, bind to and respond. But undernormal circumstances, host or self molecules do not act as antigen, they do so only in case of autoimmune disorders where self antigen is involved in which the cells acting as antigens in the same body. So option (d) is the correct answer.

3) Antibodies are glycoproteins of high molecular weight. The one end of the Ig binds to antigens (the Fab portion, so called because it is the fragment of the molecule which is antigen binding), and the other end which is crystallizable and therefore called Fc, is responsible for effector functions. Antibodies are synthesized by B cells. Antibody are composed of four polypeptide chain-two identical heavy chains and two identical light chains. The two antigen binding sites are identical, each formed by the N-terminal region of a light chain and N-terminal region of a heavy chain. The stem or the tail (Fc) is formed by the two heavy chains. It is involved in the activation of complement system binding to antigen at the surface of a cell or it may stimulate the innate immune response to act via phagocytosis. Antigens ahave determinants called epitopes. Epitopes are molecular shapes recognized by antibodies, which recognize 1 specific epitope at a time rather than the whole antigen. So option (c) is the correct answer.

4) Opsonization is the coating of antigen by molecules known as opsonins for which the antibody,s Fab region has specificity (especially IgG). Even complement system takes part in opsonization specially C3B molecule. This facilitates subsequent phagocytosis by cells possessing an Fc receptor, e.g neutrophil (polymorphonuclear leucocytes or polymorphs). Hence, opsonization is the process that facilitates the phagocytosis of antigen. Thus in opsonization and phagocytosis, both the Fab and the Fc portions of the immunoglobulin molecule are involved. So option (b) is the correct answer.

5) MHC class II is present only on a ppulation of cells known as Antigen presenting cells (APCs). These are a special class of cells which process and present exogenous antigens. APCs include macrophages, B cells and dendritic cells. It is the job of helper (CD4+) T cells to bind to antigens presented in this way, and when this happens, a helper T cell can produce special messenger molecules called cytokines, cooperate with complementary B cells to get them to clone themselves and to release antibodies and clone themselves to increase the number of this type of T cell. So option (a) is the correct answer.