Chapter 43 Mastering Biology

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1

Innate immunity_____.

A) Depends on an infected animal's previous exposure to the same pathogen

B) is based on recognition of antigens that are specific to different pathogens

C) is found only in vertebrate animals

D) is activated immediately upon infection

Answer: D

2

Engulfing-phagocytic cells of innate immunity of vertebrates include_____.

I) neutrophils

II) macrophages

III) dentritic cells

IV) natural killer cells

A) I and IV

B) II and IV

C) I, II, and III

D) I and III

Answer: C

3

the cells and signaling molecules involved in the initial stages of the inflammatory responses are ____.

A) dendritic cells and interferons

B) lymphocytes and interferons

C) mast cells and histamines

D) phagocytes and chemokines

Answer: C

4

Inflammatory responses typically include____.

A) inhibiting the release of white blood cells from bone marrow

B) release of substances to decrease the blood supply to an inflamed area

C) reduce permeability of blood vessels to conserve plasma

D) increased activity of phagocytes in an inflamed area

Answer: D

5

Mammals have Toll-like receptors (TLRs) that can recognize a kind of macromolecule that is absent from vertebrates but present in or on certain groups of pathogens, such as viral _____.

A) glycoproteins

B) phospholipids

C) double-stranded DNA

D) double-stranded RNA

Answer: D

6

Septic shock, a systemic response including high fever and low blood pressure, is a response to ____.

A) the presence of natural killer cells

B) specific forms of viruses

C) increased production of neutrophils

D) certain bacterial infections

Answer: D

7

The cells involved in innate immunity, whose absence increases the chances of developing malignant tumors, are ____.

A) cytotoxic T cells

B) B cells

C) natural killer cells

D) macrophages

Answer: C

8

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?

A) your friend has an autoimmune disorder

B) your friend had allergies

C) your friend had antibodies to that virus

D) you had an adaptive immunity to that virus

Answer: D

9

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?

A) lytic response

B) autoimmune response

C) adaptive immune response

D) inflammatory response

Answer: D

10

Acidity in human sweat is an example of ____.

A) acquired immunity

B) cell-mediated immune response

C) adaptive immunity

D) innate immunity

Answer: D

11

The eyes and the respiratory tract are both protected against infections by _____.

A) interferons produced by immune cells

B) the secretion of complement proteins

C) the release of slightly alkaline secretions

D) the secretion of lysozyme onto their surfaces

Answer: D

12

The complement system is ____.

A) a group of antimicrobial proteins that act together in a cascade fashion

B) a set of proteins involved in innate but not acquired immunity

C) a group of proteins that include interferons and interleukins

D) a set of proteins that act individually to attack and lyse microbes

Answer: A

13

Bacteria entering the body through a small cut in the skin _____.

A) stimulate apoptosis of nearby body cells

B) activate a group of proteins called complement

C) stimulate release of interferons

D) inactivate the erythrocytes

Answer: B

14

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

A) destruction of pathogens because it is acidic

B) increasing oxygen absorption

C) physically trapping pathogens

D) sweeping away debris

Answer: C

15

An antigen____.

A) is a protein attacked by an invading microorganism

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) could be an invading bacterium

Answer: B

16

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

A) having one million different immunoglobulin genes

B) temporary changes in the ways that RNA is spliced in the B cells

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

D) recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells

E) the capacity of memory cells to produce antibodies

Answer: D

17

Within a differentiated B cell, the rearrangement of DNA sequences between variable regions and joining regions is accomplished by a(n)_____.

A) reverse transcriptase

B) recombinase

C) epitopase

D) RNA polymerase

Answer: B

18

Clonal selection and differentiation of B cells activated by antigen exposure leads to the production of _____.

A) short-lived plasma cells that secrete antibodies for the antigen

B) large quantities of the antigen initially recognized

C) vast numbers of B cells with random antigen-recognition receptors

D) long-lived erythrocytes that can later secrete antibodies for the antigen

Answer: A

19

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

A) have a reduced number of B cells and be unable to form antibodies

B) be unable to differentiate and mature T cells

C) be unable to genetically rearrange antigen receptors

D) lack innate immunity

Answer: B

20

Clonal selection is an explanation for how _____.

A) macrophages can recognize specific T cells and B cells

B) an antigen can provoke production of high levels of specific antibodies

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

D) HIV (human immunodeficiency virus) can disrupt the immune system

Answer: B

21

An immunoglobulin (Ig) molecule, of whatever class, with regions symbolized as C or V, H or L, has a light chain made up of _____.

A) two C regions and two V regions

B) one H region and one L region

C) three H regions and one L region

D) one C region and one V region

Answer: D

22

Immunological memory accounts for _____.

A) the observation that some strains of the pathogen that causes dengue fever cause more severe disease than others

B) the ability of a helper T cell to signal B cells via cytokines

C) the human body's ability to distinguish self from non-self

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

Answer: D

23

Use the following information to answer the question(s) below.

An otherwise healthy student in your class is infected with EBV, the virus that causes infectious mononucleosis. The same student had already been infected when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though infected, she does not get sick.

The EBV antigen fragments will be presented by the virus-infected cells along with _____.

A) class II MHC molecules

B) a complement

C) class I MHC molecules

D) antibodies

Answer: C

24

Vaccination increases the number of _____.

A) macrophages specific for a pathogen

B) lymphocytes with receptors that can bind to the pathogen

C) epitopes that the immune system can recognize

D) major histocompatability (MHC) molecules that can present an antigen

Answer: B

25

If a patient is missing B and T cells, what would be absent from the immune response?

A) memory

B) cytokines

C) lysozymes

D) defense against bacteria

Answer: A

26

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

A) only I and III

B) only II and III

C) I, II, and III

D) only I and II

Answer: B

27

Which of the following statements are fundamental to the clonal-selection theory of how the adaptive immune system functions?
I) Each lymphocyte has a unique membrane receptor that recognizes one antigen.
II) When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical copies of itself.
III) Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen.
IV) Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated.

A) Only II, III, and IV

B) only II and IV

C) only I and III

D) only I, II, and IV

Answer: D

28

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

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

B) It allows for the destruction of antibodies.

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

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

Answer: C

29

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

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

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

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

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

Answer: C

30

A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over twenty years. One day, it recognizes a newly arrived antigen and binds to it, subsequently triggering a secondary immune response in the body. Which of the following cell types most accurately describes this cell?

A) thyroid cells

B) macrophage

C) memory cell

D) plasma cell

Answer: C

31

Which of the following statements about epitopes are correct?
I) B-cell receptors bind to epitopes.
II) T-cell receptors bind to epitopes.
III) There can be 10 or more different epitopes on each antigen.
IV) There is a one-to-one correspondence between antigen and epitope.

A) only II, III, and IV
B) only II and IV

C) only I and III

D) only I, II, and III

Answer: D

32

Which of the following pairs of proteins shares the most overall similarity in structure?

A) B-cell receptors and T-cell receptors

B) B-cell receptors and antibodies

C) T-cell receptors and antibodies

D) antibodies and antigens

Answer: B

33

To answer the following question, assume that the number of B cells producing a specific antibody is proportional to the concentration of that antibody.

On day 16, assume that one out of every 105 B cells in the body is specific for antigen A and that the antibody concentration on day 16 is about 2 × 101.Calculate the frequency of B cells specific for antigen A on day 36 if the antibody concentration on day 36 is about 8 × 103. (For practice doing calculations with proportions, try this exercise. For practice doing calculations with numbers written in scientific notation, try this exercise.)

A) 1 in 105

B) 1 in 400

C) 1 in 250

D) 1 in 20

Answer: C

34

The words “antigen” and “virus” are interchangeable.

A) True

B) false

Answer: B

35

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?

A) He was probably exposed sometime within the past two weeks, but we don’t have enough information to say more.

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

C)He was probably exposed more than several months ago, antibody production has ceased, and antibodies are no longer detectable.

Answer: B

36

Which is a true statement about memory cells?

A) They produce antibodies.

B) They engulf antigens bound by antibodies.

C) The first time an antigen is encountered, memory cells become plasma cells.

D) They have a longer lifespan than plasma cells.

Answer: D

37

Which structure is not a component of the adaptive immune system?

A) Thymus

B) Lymphatic ducts

C) Tissues

D) Spleen

Answer: C

38

True or false? B cells were originally isolated from the bursa in chickens, and their function is to produce antibodies; T cells were originally isolated from the thymus in mice, and their functions include killing host cells that are being infected with a virus.

A) True

B) False

Answer: A

39

Which of the following statements about the clonal-selection theory of immune system function is false?

A) An activated lymphocyte makes many copies of itself in response to an infection.

B) Cloned cells persist after the pathogen is eliminated.

C) Antigens are recognized by receptor proteins inside the lymphocyte.

D) Each lymphocyte recognizes one antigen.

Answer: C

40

What is the final step in the cell-mediated response to a viral infection?

A) Antibodies coat viral particles.

B) Cytotoxic T lymphocytes punch holes in the membranes of infected host cells.

C) Macrophages digest viral particles.

D) CD8+ T cells are activated.

Answer: B

41

How do cells involved in the humoral response respond to antigen presentation on the surface of a B cell?

A) Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies.

B) Helper T cells divide and produce plasma and memory cells.

C) Helper T cells secrete antibodies against the viral antigen.

D) The B cell recognizes the receptor-antigen complex and divides to produce plasma and memory cells.

Answer: A

42

Which protein presents viral antigens on the outer surface of cells?

A) antibody

B) B cell receptor

C) T cell receptor

D) MHC protein

Answer: D

43

How are cytotoxic T lymphocytes (CTLs) produced?

A) Helper T cells divide and differentiate into cytotoxic T lymphocytes.

B) Plasma cells secrete cytotoxic T lymphocytes.

C) B cells divide and differentiate into cytotoxic T lymphocytes.

D) CD8+ T cells divide and differentiate into cytotoxic T lymphocytes.

Answer: D

44

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

A) Plasma cells

B) cytotoxic T cell

C) Macrophage

D) B cell

E) helper T cell

Answer: C

45

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

A) helper T cells

B) Bacterial cells

C) Epithelial cells

D) Cytotoxic T cells

E) B cells

Answer: A

46

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

A) antigens

B) plasma cells

C) cytotoxic T cells

D) helper T cells

E) macrophages

Answer: B

47

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

A) antibodies ... antibody-mediated

B) interleukin-2 ... humoral

C) antibodies ... humoral

D) perforin ... cell-mediated

E) perforin ... humoral

Answer: D

48

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

A) T cells ... B cells

B) helper T cells ... plasma cells

C) B cells ... macrophages

D) macrophages ... B cells and T cells

E) B cells ... plasma cells and memory cells

Answer: E

49

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

A) cytotoxic T cells

B) cytokines

C) macrophages

D) memory cells

E) plasma cells

Answer: D

50

Which of these cells produce and secrete antibodies?

A) plasma cells

B) bacterial cells

C) cytotoxic T cells

D) macrophages

E) helper T cells

Answer: A