Chapter 43 Mastering Biology

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

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

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

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.)

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

mast cells and histamines

Immunological memory accounts for _____.

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

For the successful development of a vaccine to be used against a pathogen, it is necessary that _____.

the surface antigens of the pathogen stay the same

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

they respond differently to invaders (Humoral immunity is a function of B cells and antibody production, whereas cell-mediated immunity is a function of the activation of cytotoxic T cells.)

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

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.)

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

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

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

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?

Macrophages. (Macrophages are leukocytes that can engulf and digest a pathogen.)

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.)

Helper T cells are part of _____.

cell-mediated immune responses (Cell-mediated immunity depends on the activation of T lymphocytes. ;;;;; Macrophages, but not helper T cells, are phagocytic.)

Innate immunity and acquired immunity are both _____.

characteristics of all vertebrate animals (Only vertebrate animals have fully developed acquired immunity to supplement their innate immunity.)

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

helper T cells release cytokines

Inflammatory responses typically include _____.

increased activity of phagocytes in an inflamed area

Acidity in human sweat is an example of _____.

innate immunity

An antigen _____.

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.)

Macrophages are _____.

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.)

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

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.) (Immunity is a characteristic of the organism, not just the specific tissues that were infected.; Memory cells are not decimated by influenza.; Immunity persists for years and years in many types of disease.; As long as the flu-infected individual recovers, her immune system will likely be unimpaired from the infection.)

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

only II and III

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

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.)

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

the antibody having at least two binding regions

How does an antihistamine reduce allergy symptoms?

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.)

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

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 blood vessels at some distance from the wound site to allow other leukocytes and 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.)

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 _____. (see graphs on pg. 6)

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

Clonal selection is an explanation for how _____.

an antigen can provoke production of high levels of specific antibodies

Vaccination increases the number of _____.

lymphocytes with receptors that can bind to the pathogen