GRE Subject Test: Biology : Animal Biology

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

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Example Questions

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Example Question #1 : Immunobiology

Which type of cell is responsible for making antibodies?

Possible Answers:

T-lymphocytes

B-lymphocytes

Basophils

Macrophages

Correct answer:

B-lymphocytes

Explanation:

Antibodies are produced by the adaptive immune system and to antigens presented by a pathogen. The antibody-antigen complex is then detected by cytotoxic T-cells, which destroy the infected cell. The antibodies are created by B-lymphocytes, which can differentiate when exposed to a specific pathogen. Differentiated B-lymphocytes known as plasma cells are responsible for the mass production of certain antibodies.

Macrophages are derived from monocytes and serve as phagocytes in the innate immune response. Basophils are also part of the innate immune response and, along with mast cells, produce histamine to initiate the inflammatory response.

Example Question #1 : Animal Biology

Which immune cell is part of acquired immunity?

Possible Answers:

Macrophage

Neutrophil

Plasma cell

Eosinophil

Correct answer:

Plasma cell

Explanation:

Acquired immunity is developed in the body following a previously encountered infection. The innate immunity is, by definition, always present in the body and is used to attack all general forms of infection.

The granulocyte cells are considered part of innate immunity and help mediate the immune response against foreign pathogens. These cells include basophils, neutrophils, eosinophils, mast cells, and macrophages (which are differentiated from monocytes).

The adaptive immune response involves the production of antibodies against specific target antigens. Plasma cells are an integral part of the adaptive response and secrete large volumes of antibodies in response to a secondary infection by a previously encountered pathogen. T-cells and B-cells are also part of the adaptive response.

Example Question #1 : Animal Biology

Which leukocyte releases histamine during the inflammatory process?

Possible Answers:

Monocytes

Neutrophil

Basophil

B-lymphocyte

Correct answer:

Basophil

Explanation:

There are many types of white blood cells with distinct functions in the body. Neutrophils and monocytes are phagocytes that engulf bacteria. B-lymphocytes produce one type of antibody. Basophils are the least common of the leukocytes, and release histamine during inflammation.

Example Question #1 : Immunobiology

Which cell is necessary in order to allow B-ymphoytes to differentiate into plasma cells and memory B-cells?

Possible Answers:

Macrophages

Cytotoxic T-cells

Helper T-cells

Eosinophils

Correct answer:

Helper T-cells

Explanation:

Before a B-lymphocyte can proliferate and differentiate, it must present its antigen to a helper T-cell. If the helper T-cell recognizes the antigen as foreign, it will activate the B-lymphocytes, and cause them to differentiate into plasma cells and memory B-cells.

Example Question #1 : Animal Biology

Which types of leukocytes are granular?

Possible Answers:

Lymphocytes, basophils, eosinophils

Neutrophils, basophils, lymphocytes

Basophils, eosinophils, neutrophils

Basophils, lymphocytes, monocytes

Monocytes, neutrophils, eosinophils

Correct answer:

Basophils, eosinophils, neutrophils

Explanation:

The five types of leukocytes are: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Three of these (neutrophils, eosinophils, and basophils) contain granules, tiny sacs containing enzymes which can lyse microorganisms. The other two leukocytes (lymphocytes and monocytes) do not contain these granules.

Example Question #1 : Immunobiology

What do T and B cell lymphocytes have in common?

Possible Answers:

They both undergo negative selection.

They both mature in the thymus.

They are both part of the innate immune response.

They both respond to a variety of pathogens.

Correct answer:

They both undergo negative selection.

Explanation:

T and B cells are both part of the adaptive immune response. This means that they are typically made to handle very specific pathogens that may be encountered in the body. Before they are released into circulation, both must undergo negative selection, which makes sure that they do not respond to natural peptides that they encounter in the body. Failure of this step to take place can result in autoimmune diseases.

Example Question #1 : Immunobiology

Which immune cell is necessary for causing antibody "class switching" on B cells?

Possible Answers:

Helper T cells

Cytotoxic T cells

Plasma cells

Natural killer cells

Correct answer:

Helper T cells

Explanation:

Many of the modulations of the immune response are controlled by helper T cells. In order to change the type of antibody secreted by a B cell, helper T cells need to interact with them via a number of cytokines. The types of cytokines secreted by helper T cells will tell the B cells which antibodies to start secreting.

Example Question #1 : Animal Biology

Which of the following statements is true concerning antibodies?

Possible Answers:

Antibodies mark pathogens to be destroyed by phagocytic cells

Antibodies destroy pathogens once attached

An antibody can attach to multiple pathogens

Antibodies are created by helper T-cells

Correct answer:

Antibodies mark pathogens to be destroyed by phagocytic cells

Explanation:

An antibody is very specific and will only attach to one antigen. Once it does, the antibody can signal the pathogen or infected cell to be destroyed by macrophages and other phagocytic cells in the body, such as cytotoxic T-cells. The antibodies themselves cannot destroy the pathogen.

T-cells serve important functions in the communication and stimulation of antibody production, but do not actually produce antibodies.

Example Question #1 : Immunobiology

Which of the following statements is true about antibodies?

Possible Answers:

They have two recognition sites which can recognize two different antigens.

They are found on the surface of helper T cells.

They can be secreted by plasma cells.

They are seen immediately following an infection.

Correct answer:

They can be secreted by plasma cells.

Explanation:

Antibodies are part of the adaptive immune response, which means that they are formed later in an infection. Because both recognition sites have the same structure, they are responsive to only one type of antigen. They are located on the outside of B cells, and can be released freely into the plasma by plasma cells.

Example Question #1 : Immunobiology

Which antibody type is able to cross the placental barrier in order to provide temporary passive immunity for the fetus?

Possible Answers:

IgE

IgA

IgG

IgM

Correct answer:

IgG

Explanation:

Placental crossing is done mainly by IgG antibodies. These fast-acting antibodies provide temporary immunity for the fetus until it is able to have its own immune system produce sufficient antibody amounts.

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