Unit 10 hard q's

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.

I, II, and III

innate immunity

Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body. These mechanisms include physical barriers such as skin, chemicals in the blood, and immune system cells that attack foreign cells in the body.

How do prions differ from viruses? Select all that apply. a. Unlike viruses, prions do not include any nucleic acids. b. Unlike a virus, a prion is a single molecule. c. Unlike viruses, prions are infectious proteins.

a, b, and c

Which statement provides the best description of the interphase portion of the cell cycle? a. During interphase, a cell is metabolically active. b. Interphase is a brief period between mitosis and chromosome duplication. c. Interphase is a resting stage prior to cell division.

a. During interphase, a cell is metabolically active.

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 allows for the destruction of antibodies. d. It results in effector cells with specificity for a large number of antigens.

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

An immune response to a tissue graft will differ from an immune response to a bacterium because _____. a. MHC molecules of the donor may stimulate rejection of the graft tissue, but bacteria lack MHC molecules b. the graft will stimulate an autoimmune response in the recipient c. the tissue graft, unlike the bacterium, is isolated from the circulation and will not enter into an immune response d. a bacterium cannot escape the immune system by replicating inside normal body cells

a. MHC molecules of the donor may stimulate rejection of the graft tissue, but bacteria lack MHC molecules

Metaphase is characterized by _____. a. aligning of chromosomes on the equator b. splitting of the centromeres c. cytokinesis d. separation of sister chromatids

a. aligning of chromosomes on the equator

A patient who has a high level of mast cell activity, dilation of blood vessels, and acute drop in blood pressure is likely suffering from _____. a. anaphylactic shock immediately following exposure to an allergen b. a typical skin allergy (contact dermatitis) that can be treated by antihistamines c. an organ transplant, such as a skin graft d. an autoimmune disease

a. anaphylactic shock immediately following exposure to an allergen

B cells interacting with helper T cells are stimulated to differentiate when _____. a. helper T cells release cytokines b. B cells produce IgE antibodies c. cytotoxic T cells present the class II MHC molecule-antigen complex on their surface d. B cells release cytokines

a. helper T cells release cytokines

Phagocytosis of microbes by macrophages is enhanced by _____. I) the binding of antibodies to the surface of microbes II) antibody-mediated agglutination of microbes III) the release of cytokines by activated B cells a. only I and II b. only I and III c. I, II, and, III d. only II and III

a. only I and II

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct? a. Each chromosome consists of two identical chromatids. b. Each chromosome is made of a complex of DNA and associated proteins. c. The chromosomes are preparing for DNA synthesis.

b. Each chromosome is made of a complex of DNA and associated proteins.

In a humoral or antibody-mediated immune response, specific B cells are stimulated by Helper T cells to transform into plasma cells that secrete antibodies. What would be an important feature added to B cells In this transition process? a. Duplication of lysosomes in order to store the antibodies before transport. b. Increased rough endoplasmic reticulum in order to have the surface area needed for antibody production. c. Duplication of specific gene sequences for the appropriate antibody.

b. Increased rough endoplasmic reticulum in order to have the surface area needed for antibody production.

Select the pathway that would lead to the activation of cytotoxic T cells. a. complement is secreted → B cell contacts antigen → helper T cell activated → cytokines released b. body cell becomes infected with a virus → new viral proteins appear → class I MHC molecule-antigen complex displayed on cell surface c. cytotoxic T cells → class II MHC molecule-antigen complex displayed → cytokines released → cell lysis d. B cell contact antigen → helper T cell is activated → clonal selection occurs

b. body cell becomes infected with a virus → new viral proteins appear → class I MHC molecule-antigen complex displayed on cell surface

The number of major histocompatability (MHC) protein combinations possible in a given population is enormous. However, an individual in that diverse population has a far more limited array of MHC molecules because _____. a. MHC proteins from one individual can only be of class I or class II b. each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene c. once a B cell has matured in the bone marrow, it is limited to two MHC response categories the MHC proteins are made from several different d. gene regions that are capable of rearranging in a number of ways

b. each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene

Inflammatory responses typically include _____. a. inhibiting the release of white blood cells from bone marrow b. increased activity of phagocytes in an inflamed area c. release of substances to decrease the blood supply to an inflamed area d. reduced permeability of blood vessels to conserve plasma

b. increased activity of phagocytes in an inflamed area

A nonfunctional CD4 protein on a helper T cell would result in the helper T cell being unable to _____. a. lyse tumor cells b. interact with a class II MHC-antigen complex c. stimulate a cytotoxic T cell d. respond to T-independent antigens

b. interact with a class II MHC-antigen complex

The eyes and the respiratory tract are both protected against infections by _____. a. the release of slightly alkaline secretions b. the secretion of lysozyme onto their surfaces c. the secretion of complement proteins d. interferons produced by immune cells

b. the secretion of lysozyme onto their surfaces

Select the correct statement about the immune system. a. Adaptive immunity is characteristic of invertebrates and vertebrates. b. Antibodies are secreted by T cells. c. All antigen receptors produced by a single B cell or T cell are identical and bind to the same epitope.

c. All antigen receptors produced by a single B cell or T cell are identical and bind to the same epitope.

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 studentfaculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times. Which of the following question might be answered by using the method described? a. How many cells are produced by the culture per hour? b. How many picograms of DNA are made per cell cycle? c. What is the length of the S phase of the cell cycle? d. When do spindle fibers attach to chromosomes?

c. What is the length of the S phase of the cell cycle?

Acidity in human sweat is an example of _____. a. cell-mediated immune responses b. acquired immunity c. innate immunity d. adaptive immunity

c. innate immunity

The cyclin component of MPF is destroyed toward the end of which phase? a. G1 b. G2 c. S d. M

d. M

The herpes viruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can later reactivate, replicate again, and infect others. If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection? a. treat HSV lesions to shorten the breakout b. vaccinate of all persons with preexisting cases of HSV c. educate people about avoiding sources of infection d. interfere with new viral replication in preexisting cases of HSV

d. interfere with new viral replication in preexisting cases of HSV

CD4 and CD8 are _____. a. molecules on the surface of antigen-presenting cells where they enhance B cell activity b. proteins secreted by antigen-presenting cells c. receptors present on the surface of natural killer cells d. molecules present on the surface of T cells where they interact with major histocompatability (MHC) molecules

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