Which secretion is not a barrier that prevents pathogens from entering the body?

A. Mucus.

B. Ear wax.

C. Antigens.

D. Lysozyme.

C. Antigens.

Antigens are foreign molecules that initiate an immune response.

True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils.

False

The leukocytes of the innate immune system are mast cells, macrophages, and neutrophils.

How do cells involved in the innate immune response detect the presence of pathogens?

A. Antibodies bind to the pathogens.

B. Leukocytes recognize the entire pathogen.

C. Leukocytes recognize the secretions from a pathogen.

D. Leukocytes recognize unique molecules on pathogens.

D. Leukocytes recognize unique molecules on pathogens.

Pattern-recognition receptors on leukocytes recognize and bind to unique molecules on the pathogens, such as the amino acid N-formylmethionine in bacteria. This receptor binding leads to activation of the innate immune response.

Which of the following cells can engulf a pathogen?

A. Macrophages.

B. Mast cells.

C. Cytokines

D. Platelets.

A. Macrophages.

Macrophages are leukocytes that can engulf and digest a pathogen.

Which of the following statements best describes the role of mast cells in the inflammatory response?

A. They secrete substances that degrade bacterial cell walls and engulf and digest the invaders.

B. They release chemicals that constrict blood vessels at some distance from the wound site.

C. They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream.

D. They release cytokines to stimulate the release of additional neutrophils and macrophages.

C. They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream.

Mast cells release chemicals that dilate nearby capillaries, increasing their permeability and allowing blood components to enter the region from the bloodstream, thus causing localized swelling.

Which of the following events occurs first when a wound that breaks the skin has occurred?

A. Macrophages present bacterial proteins as antigens on their plasma membrane.

B. Platelets release proteins that form clots and decrease bleeding.

C. Mast cells secrete chemical messengers to regulate blood flow to the wound.

D. Neutrophils secrete substances that degrade bacterial cell walls.

B. Platelets release proteins that form clots and decrease bleeding.

The first response to broken skin is the release of clotting proteins from platelets in the bloodstream, which decreases bleeding and helps to seal the wound.

True or False? The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors.

True.

The site of inflammation may also become red due to increased blood flow at the site; the inflammatory response continues until all invaders are eliminated and the wound is repaired.

Innate immunity and acquired immunity are both _____.

A. dependent on surface secretions from sebaceous and sweat glands, which give the skin an acidic pH that is unfavorable for bacterial colonization

B. dependent exclusively on cell-mediated responses

C. dependent on tears, saliva, and mucous secretions that contain lysozyme, an enzyme that digests bacterial cell walls

D. characteristics of all vertebrate animals

E. based on the trapping of microbes by mucus

D. characteristics of all vertebrate animals

Only vertebrate animals have fully developed acquired immunity to supplement their innate immunity.

Macrophages are _____.

A. large, phagocytic cells that can leave the circulation and enter the tissues of the body

B. the best defense against parasites

C. antigen-presenting cells that originate from neutrophils

D. cells that induce the lysis of virus-infected body cells

E. short-lived cells that self-destruct soon after engulfing foreign invaders

A. large, phagocytic cells that can leave the circulation and enter the tissues of the body

Once resident in the tissues, macrophages are active phagocytes that capture and digest many microorganisms.

The cells and signaling molecules involved in the initial stages of the inflammatory response are _____.

A. lymphocytes and interferons

B. mast cells and histamines

C. phagocytes and chemokines

D. dendritic cells and interferons

B. mast cells and histamines

Inflammatory responses typically include _____.

A. release of substances to decrease the blood supply to an inflamed area

B. increased activity of phagocytes in an inflamed area

C. inhibiting the release of white blood cells from bone marrow

D. reduced permeability of blood vessels to conserve plasma

B. increased activity of phagocytes in an inflamed area

Mutant fruit flies that make only one antimicrobial peptide were tested for survival after infection with Neurospora crassa fungi or with Micrococcus luteus bacteria.

The results shown in the graphs support the hypothesis that _____.

A. adding the defensin gene to such mutants protects them from death by fungal infection

B. the presence of any single antimicrobial peptide protects against both infective agents

C. adding the drosomycin gene to such mutants protects them from death by fungal infection

D. wild-type flies with the full set of genes for antimicrobial peptides are highly susceptible to these infective agents

C. adding the drosomycin gene to such mutants protects them from death by fungal infection

Acidity in human sweat is an example of _____.

A. acquired immunity

B. adaptive immunity

C. cell-mediated immune responses

D. innate immunity

D. innate immunity

An antigen _____.

A. could be an invading bacterium

B. is a foreign molecule that evokes a specific response by a lymphocyte

C. is a protein molecule that helps defend the body against disease

D. induces development of white blood cells in the bone marrow

E. is a protein attacked by an invading microorganism

B. is a foreign molecule that evokes a specific response by a lymphocyte

Antigen molecules can be a part of any type of organism. Antigen molecules could also be a part of a product of an organism such as pollen or feces.

The fact that there are about a million different antigen receptors possible in human B cells is based on _____.

A. temporary changes in the ways that RNA is spliced in the B cells

B. the capacity of memory cells to produce antibodies

C. constant changes in the splicing pattern of receptor genes after the differentiation of the B cell

D. having one million different immunoglobulin genes

E. recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells

E. recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells

Which variable and which joining segments are recombined in the DNA of the differentiated B cells determine which receptor proteins will be made in that B cell.

Clonal selection is an explanation for how _____.

A. macrophages can recognize specific T cells and B cells

B. HIV (human immunodeficiency virus) can disrupt the immune system

C. V, J, and C gene segments are rearranged

D. an antigen can provoke production of high levels of specific antibodies

D. an antigen can provoke production of high levels of specific antibodies

Immunological memory accounts for _____.

A. the human body's ability to distinguish self from non-self

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

D. the ancient observation that someone who had recovered from the plague could safely care for those newly diseased

How does an antihistamine reduce allergy symptoms?

A. An antihistamine kills mast cells, blocking an allergic reaction.

B. An antihistamine binds pollen antigens, preventing them from provoking an allergic reaction.

C. An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells.

C. An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells.

Allergens attach to the antigen-binding sites of these IgE antibodies. This attachment links adjacent IgE molecules, inducing the mast cell to release histamine and other inflammatory chemicals from granules. Antihistamines diminish allergy symptoms (and inflammation) by blocking receptors for histamine. Read about allergies.

Lymphocytes mature in the _____.
I) spleen
II) thymus
III) bone marrow

A. only I and III

B. I, II, and III

C. only II and III

D. only I and II

C. only II and III

Vaccination increases the number of _____.

A. epitopes that the immune system can recognize

B. lymphocytes with receptors that can bind to the pathogen

C. major histocompatability (MHC) molecules that can present an antigen

D. macrophages specific for a pathogen

B. lymphocytes with receptors that can bind to the pathogen

What major advantage is conveyed by having a system of adaptive immunity?

A. It enables a rapid defense against an antigen that has been previously encountered.

B. It enables an animal to counter most pathogens almost instantly the first time they are encountered.

C. It results in effector cells with specificity for a large number of antigens.

D. It allows for the destruction of antibodies.

A. It enables a rapid defense against an antigen that has been previously encountered.

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

A. One binds a receptor called BCR (B-cell receptor), while the other recognizes a receptor called TCR (T-cell receptor).

B. One has a major role in antibody production, while the other has a major role in cytotoxicity.

C. T cells are produced in the thymus and B cells are produced in the bone marrow.

D. B cells are activated by free-floating antigens in the blood or lymph. T cells are activated by membrane-bound antigens.

B. One has a major role in antibody production, while the other has a major role in cytotoxicity.

Cell-mediated immunity differs from humoral immunity in that _____.

A. cell-mediated immunity is longer lasting

B. clonal selection occurs only in cell-mediated immunity

C. a humoral response is mounted more quickly

D. they respond differently to invaders

E. a subsequent secondary immune response can occur in humoral immunity

D. they respond differently to invaders

Helper T cells are part of _____.

A. innate immunity

B. a group of phagocytic white blood cells

C. cell-mediated immune responses

D. the complement systemthe first cells to bind to antigens

C. cell-mediated immune responses

Cell-mediated immunity depends on the activation of T lymphocytes.

B cells interacting with helper T cells are stimulated to differentiate when _____.

A. B cells produce IgE antibodies

B. B cells release cytokines

C. cytotoxic T cells present the class II MHC molecule-antigen complex on their surface

D. helper T cells release cytokines

D. helper T cells release cytokines

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

A. the antibody having at least two binding regions

B. denaturation of the antibodies

C. bonds between class I and class II MHC molecules

D. disulfide bridges between the antigens

A. the antibody having at least two binding regions

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. the pathogen has only one epitope

C. the major histocompatability (MHC) molecules are heterozygous

D. all of the surface antigens on the pathogen be identified

A. the surface antigens of the pathogen stay the same

A primary reason for needing a new vaccine for influenza each year is that _____.

A. the influenza virus might proliferate in different tissues during each subsequent year, and immune memory is limited to those tissues initially infected

B. the first infection with influenza weakens the immune system

C. influenza is a disease that causes the apoptosis of all memory cells

D. immunity typically disappears one month after recovery from a disease

E. mutation in the influenza virus is frequent

E. mutation in the influenza virus is frequent

The virus that causes one year's flu outbreak has a high rate of mutation, resulting in antigenic variation that the immune system cannot recognize.