Question 1

Which option best describes why Jenner's use of cowpox virus as a vaccine against the smallpox virus was successful?

Accepted Answer

Jenner's use of cowpox virus as a vaccine against the smallpox virus was successful because there are some epitopes (antigenic determinants) common to both pox viruses. This means that the immune system's response to cowpox can also recognize and fight off smallpox.

Question 2

The number of major histocompatibility (MHC) protein combinations possible in a given population is enormous. However, an individual in the population has a far more limited array of MHC molecules because ________.

Accepted Answer

Each individual inherits only two alleles for each MHC gene, one from each parent, which limits the variety of MHC molecules an individual can produce despite the large number of possible alleles in the population.

Question 3

Which of these is not part of insect immunity?

Accepted Answer

Insects do not have natural killer cells, which are a component of the vertebrate immune system. Their immunity relies on mechanisms like enzyme activation, phagocytosis by hemocytes, and the production of antimicrobial peptides.

Question 4

Which of the following can result in naturally acquired passive immunity?

Accepted Answer

Naturally acquired passive immunity occurs when antibodies are passed from mother to fetus through the placenta. This provides the newborn with immediate, though temporary, protection against pathogens.

Question 5

Which of the following components of the immune system is most likely to be the same in identical twins?

Accepted Answer

Identical twins share the same genetic makeup, including the genes that encode for major histocompatibility (MHC) molecules. MHC molecules are crucial for the immune system's recognition of foreign molecules, and since they are genetically determined, identical twins will produce the same kinds of MHC molecules.

Question 6

The figure shows the progress of an untreated HIV infection. Which curve represents the concentration of helper T cells in the blood?

Accepted Answer

The answer of The figure shows the progress of an...

Question 7

Some people are allergic to dust mites, which are tiny insects that commonly live in house dust. Which of the following is the most immediate outcome if someone who is allergic to dust mites inhales dust years after they are first exposed to dust mites?

Accepted Answer

When someone allergic to dust mites inhales the allergen, IgE antibodies already bound to mast cells recognize and bind the allergen, leading to an allergic reaction.

Question 8

Wiskott-Aldrich syndrome is an inherited X-linked recessive disorder characterized by low platelet count and a compromised immune system among other symptoms. Which answer best describes Wiskott-Aldrich syndrome?

Accepted Answer

Wiskott-Aldrich syndrome is an inborn immunodeficiency disease, meaning it is a genetic disorder present from birth that affects the immune system, leading to a lower platelet count and increased susceptibility to infections, among other symptoms.

Question 9

Which of the following would help a virus avoid triggering an effective adaptive immune response?
I. having frequent mutations in genes for surface proteins
II. building the viral shell from host proteins
III. producing proteins very similar to those of other viruses
IV. infecting and killing helper T cells

Accepted Answer

I. Frequent mutations in genes for surface proteins can help a virus evade the immune system by altering its antigens and thus avoiding recognition by antibodies.II. Building the viral shell from host proteins can help the virus avoid detection by the immune system because the viral shell will mimic host cells, making it harder for the immune system to recognize the virus as foreign.IV. Infecting and killing helper T cells can impair the adaptive immune response by directly targeting and diminishing the population of cells that play a crucial role in activating other immune cells.

Question 10

An epitope associates with which part of an antigen receptor or antibody?

Accepted Answer

Epitopes, or antigenic determinants, are the specific parts of an antigen that are recognized and bound by the antigen receptors on lymphocytes or by antibodies. The binding occurs at the variable regions of both the heavy and light chains of the antibody or antigen receptor, where the specific shape and charge complementarity to the epitope is found. These variable regions are responsible for the specificity of antigen recognition.

Question 11

Which of the following best explains why a bone marrow transplant may not be appropriate from a given donor to a given recipient even though they are compatible for blood transfusions?

Accepted Answer

A bone marrow transplant requires compatibility beyond just matching blood types, specifically a match in major histocompatibility (MHC) proteins. Blood transfusions are based on blood type compatibility, but bone marrow transplants require a match in the MHC proteins to prevent immune rejection.

Question 12

Which of the following gives the best example for the ability of some viruses to remain inactive (latent) for a period of time?

Accepted Answer

Herpes simplex viruses can remain latent in the body and become reactivated in response to physiological or emotional stress, making them a prime example of viruses that can exist in an inactive state for periods of time before re-emerging.

Question 13

A patient has a high level of mast cell activity, dilation of blood vessels, and acute drop in blood pressure. Which condition is most consistent with these symptoms?

Accepted Answer

The symptoms described are characteristic of anaphylactic shock, a severe allergic reaction that involves a sudden drop in blood pressure, dilation of blood vessels, and increased mast cell activity, leading to the release of large amounts of histamine and other chemicals into the bloodstream.

Question 14

Which treatment is most appropriate for an individual complaining of watery, itchy eyes and sneezing after being given a flower bouquet?

Accepted Answer

Antihistamines are the most appropriate treatment for symptoms of allergic reactions such as watery, itchy eyes and sneezing, which are likely due to exposure to pollen in the flower bouquet.

Question 15

Yearly vaccinations for influenza viruses are necessary for humans because ________.

Accepted Answer

Rapid mutation in flu viruses results in changes to the surface proteins (antigens), making it necessary to update vaccines annually to match these changes and provide effective protection.

Question 16

Which of the following components of the immune system destroys cancer cells by forming holes in plasma membranes and triggering apoptosis?

Accepted Answer

Cytotoxic T cells, part of the adaptive immune system, can directly kill cancer cells by recognizing specific antigens on the cells' surface. They do this by releasing perforin and granzymes, where perforin forms pores in the target cell's membrane, allowing granzymes to enter and induce apoptosis.

Question 17

Which of the following is crucial to activation of the adaptive immune response?

Accepted Answer

The presentation of an MHC-antigen complex on a cell surface is crucial for the activation of the adaptive immune response. This process allows T cells to recognize and respond to specific antigens, initiating the adaptive immune response.

Question 18

Which of the following enhances phagocytosis of microbes by macrophages?
I. the binding of antibodies to the surface of microbes
II. antibody-mediated opsonization of microbes
III. the release of cytokines by activated B cells

Accepted Answer

I and II both describe mechanisms that enhance the phagocytosis of microbes by macrophages. The binding of antibodies to microbes (I) and antibody-mediated opsonization (II) directly facilitate the recognition and ingestion of microbes by macrophages. The release of cytokines by activated B cells (III) is more related to the regulation of immune responses rather than directly enhancing phagocytosis.

Question 19

Which of the following is the best definition of autoimmune disease?

Accepted Answer

Autoimmune diseases occur when the immune system mistakenly attacks the body's own cells, tissues, and organs, treating them as foreign invaders. This is due to a loss of self-tolerance, where the immune system fails to recognize the body's own molecules as self and instead treats them as nonself.

Question 20

Which treatment could relieve the symptoms of an individual who has been bitten by a poisonous snake that has a fast-acting toxin?

Accepted Answer

Injection of antibodies to the toxin is the correct treatment for someone bitten by a poisonous snake with a fast-acting toxin. These antibodies can neutralize the toxin directly, offering immediate relief from the symptoms. Vaccinations (A) would not work quickly enough, as they rely on the body's immune response to build up over time. Interleukin-1 (C) and interferon (D) are involved in immune responses but do not directly neutralize toxins.

Quiz 47: Animal Defenses Against Infection