Chapter 43 Homework

Which of these binds to receptor molecules on the host cell membrane?

A glycoproteins

Which of the following statements is not true? An antibody has more than one antigen-binding site. A lymphocyte has receptors for multiple different antigens. An antigen can have different epitopes. A liver or muscle cell makes one class of MHC molecule.

A lymphocyte has receptors for multiple different antigens.

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

Antigens; Antigens are foreign molecules that initiate an immune response.

Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____.

B cells ... plasma cells and memory cells

Which of these is reverse transcriptase?

C

Which of these is the viral genome?

E

The words "antigen" and "virus" are interchangeable.

False; A virus, like other pathogens, has numerous antigens on its surface, so the words "antigen" and "virus" cannot be used interchangeably.

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.

A man who has been exposed to the flu virus is tested by his physician. The physician notes that the virus is present but no measurable level of antibodies corresponding to the virus are detected in his body. What might this mean?

He was probably exposed a few days ago and clonal selection has yet to produce plasma cells.

____ interact with the antigen-class II MHC complex presented by macrophages.

Helper T cells

Arrange in the correct sequence these components of the mammalian immune system as it first responds to a pathogen. I) Pathogen is destroyed. II) Lymphocytes secrete antibodies. III) Antigens from a pathogen bind to antigen receptors on lymphocytes. IV) Lymphocytes specific to antigens from a pathogen become numerous. V) Only memory cells remain.

III → IV → II → I → V

Which of the following is an INACCURATE statement regarding lymph nodes? Immune system cells are only located in the cortex. Lymph is channeled toward the hilus. Nodes can have several efferent and afferent vessels. Trabeculae compartmentalize the node.

Immune system cells are only located in the cortex.

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.

Tissues are immunogically "typed" before an organ transplant to make sure that the donor and recipient match as closely as possible in their _____.

MHC (major histocompatibility complex) proteins

Which of the following cells can engulf a pathogen?

Macrophages

________ is a characteristic of adaptive immunity but not innate immunity.

Memory

________ are cells of the mammalian innate immune response that help destroy tumors.

Natural killer cells

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.

Which is a true statement about memory cells?

They have a longer lifespan than plasma cells.

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.

________ are receptor molecules on mammalian cells that recognize macromolecules that are present in or on certain groups of pathogens.

Toll-like receptors

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

You and a friend were in line for a movie when you noticed the woman in front of you sneezing and coughing. Both of you were equally exposed to the woman's virus, but over the next few days, only your friend acquired flu-like symptoms and was ill for almost a week before recovering. Which one of the following is a logical explanation for this?

You had an immunological memory of that virus.

The complement system is ________.

a group of proteins that act together in a cascade fashion the complement system is part of the immune system that enhances the ability of antibodies and phagocytes to clear pathogens from the individual promotes inflammation and attack on pathogens part of the innate immune system that helps the adaptive immune system

Clonal selection is an explanation for how ________.

an antigen can provoke production of high amounts of specific antibodies

Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____.

antibodies from plasma cells

A newborn who is accidentally given a drug that destroys the thymus would most likely ________.

be unable to differentiate and mature T cells

Which of the following are similarities between B cells and T cells? I) They both recognize antigen using immunoglobulin receptors. II) Both B cells and T cells undergo clonal selection after encountering an antigen. III) B cells and T cells both maintain an immunological memory of previously encountered antigens.

both II and III

What is the function of reverse transcriptase?

catalyzing the formation of DNA from a RNA template

Innate immunity and acquired immunity are both _____.

characteristics of all vertebrate animals

Which of the following components of the immune system destroys cancerous cells by punching holes in plasma membranes and triggering apoptosis? toll-like proteins macrophages plasma cells cytotoxic T cells

cytotoxic T cells

T cells of the immune system include ________.

cytotoxic and helper cells

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

helper T cells release cytokines

What is the source of a viral envelope?

host cell membrane

Inflammatory responses typically include ________.

increased activity of phagocytes in an inflamed area

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student—faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times. Use the following information to answer the question below. The research team used their experiments to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that __________.

infection causes lymphocytes to divide more rapidly

A boy falls while riding his bike. A scrape on his hand almost immediately begins to bleed and becomes red, warm, and swollen. What response is occurring?

inflammatory response

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.

Innate immunity ________

is the first, and most general, mechanism of protection against pathogens

Vaccination increases the number of

lymphocytes with receptors that can bind to the pathogen.

Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium?

macrophage

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

mast cells and histamines

Which of these cells is responsible for the rapidity of the secondary immune response?

memory cells

CD4 and CD8 are ________.

molecules present on the surface of T cells where they interact with major histocompatibility (MHC) molecules

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

mutation in the influenza virus is frequent

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

only II and III

The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response.

perforin ... cell-mediated

Mucus occurs in both the respiratory and digestive tracts. What is its main immunological function?

physically trapping of pathogens

B cells that have been stimulated by interleukin-2 develop into _____.

plasma cells

Which of these cells produce and secrete antibodies?

plasma cells

Which of the following would not help a virus avoid triggering an adaptive immune response? having frequent mutations in genes for surface proteins infecting cells that produce very few MHC molecules producing proteins very similar to those of other viruses infecting and killing helper T cells

producing proteins very similar to those of other viruses

Double-stranded viral DNA is incorporated into a host cell as a

provirus

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

What enzyme is responsible for the process seen here?

reverse transcriptase

The genetic material of HIV consists of _____.

single-stranded RNA