GRE Subject Test: Biology : Understanding Immunological Processes

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Understanding Immunological Processes

If a person has an A blood type, which of the following statements is true?

Possible Answers:

The person makes B antibodies

The person cannot be given type O blood

The person makes A antibodies

The person can be given type B blood

Correct answer:

The person makes B antibodies

Explanation:

The type of blood a person has not only tells us which antibodies they create, but also which blood type can be given in the event of a transfusion. A person with type A blood has A antigens on his red blood cells. As a result, the person does not make A antibodies; these would bind to the A antigens and initiate an autoimmune response.

Because the person does not make the B antigen, there are B antibodies in the body. This means that the person cannot be given type B blood. B type blood cells would be targeted by the antibodies present in the body, causing an autoimmune reaction against the foreign blood. Since type O blood does not have any surface antigens, this blood type can be given to anybody. No antibodies will react with type O blood.

Example Question #12 : Animal Biology

Which is not a function of B cells?

Possible Answers:

Ability to form memory cells

Presentation of antigen to T cells

Secretion of extracellular traps

Cytokine and chemokine production

Antibody production

Correct answer:

Secretion of extracellular traps

Explanation:

B cells play numerous integral roles in the immune response against foreign pathogens (viruses, bacteria, and fungi), including forming transient microenvironments called germinal centers, where they produce long-lived plasma cells that are high affinity for specific antigen and memory B cells. They also serve as antigen-presenting cells and producers of cytokines and chemokines; However, B cells are not able to produce extracellular traps, which primarily are composed of DNA and work to trap pathogens. Neutrophils produce extracellular traps.

Example Question #13 : Animal Biology

Which of the following statements is true?

Possible Answers:

Naive B cells need more than one signal to become activated towards a specific antigen.

Female sex hormones do not play an important role in the pathogenesis of autoimmune disease.

In the prevention of autoimmunity, T cell tolerance is more critical than B cell tolerance against self-nuclear antigens.

The elimination of autoreactive lymphocytes during central tolerance is more important in the prevention of autoimmunity than peripheral tolerance.

Healthy individuals do not have any B cells that are reactive against self-antigen.

Correct answer:

Naive B cells need more than one signal to become activated towards a specific antigen.

Explanation:

Naive B cells (and most other immune cell subtypes) need more than one signal to become activated. They normally need B cell receptor signaling (signal 1), costimulation by other receptors (signal 2), and cytokines/chemokines (signal 3). This system is necessary in order to prevent aberrant activation of lymphocytes (safeguard against autoimmunity).  

In regards to the other statements, there are numerous autoreactive B cells at any given time due to the stochastic nature of VDJ recombination and germinal center reactions. Therefore, tolerance mechanisms and checkpoints are incredibly important to keep these cells in check; central and peripheral tolerance are equally important. Self-nuclear reactive B cells and T cells are both necessary and critical in autoimmune pathogenesis. Female sex hormones are definitely believed to contribute greatly to autoimmune disease pathogenesis (e.g. estrogen). Over 75% of autoimmune patients are women.

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