High School Biology : Understanding Adaptive Immunity

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #831 : High School Biology

The spleen is an intra-abdominal organ whose function is __________.

Possible Answers:

excretion of liquid wastes

still largely unknown

related mostly to immunological abilities

related to the regulation of body fat metabolism

the production of gastrin, which it delivers to the stomach

Correct answer:

related mostly to immunological abilities

Explanation:

The spleen is like a giant lymph node, and it is organized in a somewhat similar manner. Although it can be surgically removed if it is damaged, such patients are at life-long risk of death from fairly ordinary infectious processes. The spleen is a reservoir of immune competence. Blood passes through the spleen for exposure to white blood cells. When the white blood cells detect antigens or foreign particles in the blood, they initiate the immune response. The spleen is essentially a screening center to check the blood for contaminants.

Example Question #832 : High School Biology

When a person is exposed to an organism and produces specific antibodies against it, this type of immunity is referred to as __________.

Possible Answers:

cell-mediated

congenital

adaptive

passive

innate

Correct answer:

adaptive

Explanation:

Adaptive immunity occurs when antibodies are produced as a result of exposure to a pathogen or immunization. These antibodies are specific for the particular microorganism and memory cells are produced. Cell-mediated immunity is a direct form of defense based on the action of lymphocytes to attack foreign cells and destroy them. Congenital immunity is immunity one is born with. This may result from antibodies received from the mother's blood. Innate immunity is not pathogen-specific and includes the secretion of proteins and the activities of natural killer cells. Passive immunity involves the introduction of preformed antibodies into an unprotected individual. This may occur through infusion of immune globulin or antibodies that pass from the mother to the fetus through the placenta.

Example Question #833 : High School Biology

How is VDJ recombination indispensible for adaptive immunity?

Possible Answers:

It prevents integration of viral DNA into host DNA 

It allows for the generation of diverse antigens to recognize many antibodies

It promotes clotting and macrophage recruitment to wounds

VDJ recombination is not involved in adaptive immunity

It allows for the generation of diverse and variable antibodies that are able to recognize a myraid of antigens

Correct answer:

It allows for the generation of diverse and variable antibodies that are able to recognize a myraid of antigens

Explanation:

VDJ recombination occurs during early B- and T-cell maturation, resulting in diverse antibodies and T-cells. This DNA recombination occurs between the V, D, and J segments of the antibody or T-cell before transcription occurs. As a result, a unique sequence is generated, transcribed, and then translated to a functional protein. This recombination is responsible for creating the unique series of antibodies that the body is capable of producing in order to detect the various antigens represented by foreign pathogens.

Example Question #834 : High School Biology

Which of the following is true regarding B cell and T cell interactions? 

Possible Answers:

Both B cells and T cells can activate each other

B cells can activate T cells but T cells cannot activate B cells

T cells can activate B cells but B cells cannot activate T cells

B cells and T cells do not activate each other

Correct answer:

T cells can activate B cells but B cells cannot activate T cells

Explanation:

B cells and T cells are both part of the adaptive immunity. B cells secrete antibodies that bind to foreign antigens. Upon binding to a specific antigen, B cells can be activated by T cells, which facilitate the synthesis of specific antibodies for the antigen. This enhances the antibody-antigen binding and allows for a better immune response. T cells have receptors on their surface that detect antigens. Once they detect the antigen, T cells can activate B cells and other immune system cells (such as macrophages and neutrophils) to eliminate the foreign antigen. B cells do not play a role in the activation of T cells. 

Example Question #1 : Understanding Adaptive Immunity

A researcher is analyzing a specific immune complex that is made up of an antibody-antigen complex. What can the researcher conclude about this immune response?

Possible Answers:

It involves T cells and a cell-mediated immune response.

It involves B cells and a cell-mediated immune response.

It involves B cells and a humoral immune response.

It involves T cells and a humoral immune response.

Correct answer:

It involves B cells and a humoral immune response.

Explanation:

The question states that the immune complex has antibodies bound to antigens. Recall that B cells eliminate pathogens by secreting antibodies. These antibodies bind to antigens and release factors called cytokines. Cytokines recruit phagocytic cells like macrophages and neutrophils that kill the infected cell. They also activate a part of the innate immune system called the complement, which aids in the elimination of the pathogen. This type of immune response is called a humoral immune response. Elimination of the pathogen using T cells is called a cell-mediated immune response.

Note that both the humoral and the cell-mediated immune responses are very specific responses that are part of the adaptive immunity. Innate immunity involves non-specific immune responses via macrophages, granulocytes (neutrophils, eosinophils, and basophils), complement system, and NK cells.

Example Question #2 : Understanding Adaptive Immunity

Which of the following is/are characteristic(s) of T cells?

            I. T cells can differentiate into plasma cells.

            II. T cells can differentiate into cells that inhibit activity of other T cells.

            III. HIV attacks helper T cells.

Possible Answers:

I and III

I

II and III

I and II

Correct answer:

II and III

Explanation:

Plasma cells are circulating cells that form part of adaptive immunity that secrete antibodies to specific antigens. These cells arise from naïve B cells. Broadly specific naïve B cells have the ability to bind to several antigens. Once bound, these naïve B cells differentiate into plasma cells that secrete antibodies that are very specific to the antigen. T cells facilitate this differentiation, but only B cells give rise to plasma cells.

A naïve T cell has the ability to differentiate into three kinds of cells. First, it can differentiate into a helper T cell. These cells facilitate the activation of other immune cells such as B cells, macrophages, and granulocytes. Second, a naïve T cell can differentiate into a cytotoxic T cell. These cells bind to infected cells and induce their death. Third, a naïve T cell can differentiate into a regulatory T cell. These T cells bind to the same antigens as the first two cells; however, instead of initiating an immune response, they regulate it by suppressing the activity of T cells.

HIV is a virus that likes to reside inside helper T cells. A person infected with HIV will have a decreased helper T cell count, which makes the person more susceptible to other opportunistic infections (infections that only occur in immune-compromised individuals). A patient with very low helper T cell count develops AIDS and often passes away due to these opportunistic infections.

Example Question #837 : High School Biology

CD8 is a surface glycoprotein found in many T cells. Which of the following T cells will NOT have a CD8?

Possible Answers:

All of the these T cells will have CD8.

A T cell that participates in the elimination of virus infected cells

A T cell that participates in the elimination of extracellular bacterial cells

A T cell that participates in the elimination of cancer cells

Correct answer:

A T cell that participates in the elimination of extracellular bacterial cells

Explanation:

There are three kinds of T cells: helper T cells, cytotoxic T cells, and regulatory T cells. All T cells have glycoproteins on their surfaces that act as receptors. CD4 and CD8 are two glycoproteins that can be found on T cells. Helper T cells and regulatory T cells have CD4 glycoproteins, whereas cytotoxic T cells have CD8. These glycoproteins serve as markers to distinguish between T cell types.

The question is asking about CD8, or cytotoxic, T cells. Recall that cytotoxic T cells bind to infected cells and induce their death. Typically, cytotoxic T cells bind to infected cells that have the pathogen inside them (meaning intracellular pathogens). Intracellular pathogens include viruses and intracellular bacteria; therefore, T cells that attack these cells will be CD8 cells. In addition, cytotoxic T cells also attack cancer cells; therefore, these T cells will also be CD8 cells.

Extracellular bacterial cells do not infect host cells; therefore, these bacteria are eliminated via the helper T cells. These T cells bind to the bacteria and activate other immune cells such as B cells, macrophages, and granulocytes that eliminate the bacteria.

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