MCAT Biology : Adaptive and Innate Immunity

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

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Example Question #55 : Immune System

Inflammation is an important response of the immune system. The vasodilation of blood vessels allows for important cells of the innate immune system to move out of the blood and into the surrounding tissue. Which of the following members of the innate immune system is responsible for causing inflammation at the site of infection?

Possible Answers:

Natural Killer Cells

Mast cells

Macrophages

Dendritic cells

Correct answer:

Mast cells

Explanation:

The correct answer is mast cells. Mast cells as well as granulocytes participate in the innate immune system's inflammatory response. Mast cells release histamine as well as other chemicals that allow for other cells to move from the blood stream into the tissue at the site of infection. 

Example Question #56 : Immune System

The HIV virus infects which of the following cells in order to diminish coordinated immune responses against pathogens?

Possible Answers:

Neutrophils

Basophils

Macrophages

Cytotoxic T -cells

Helper T-cells

Correct answer:

Helper T-cells

Explanation:

The HIV virus readily attacks Helper T-cells because these cells have a signaling-cascade effect on most immune cells. Most importantly, helper T-cells stimulate B-cells to produce antibodies. As the virus destroys the helper T-cells, it effectively negates the adaptive immune system, making the body exceptionally vulnerable to infection.

Example Question #57 : Immune System

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the loss of tolerance to self antigens leading to the presence of high autoantibody titers. Dysregulated peripheral tolerance and hyperactive germinal centers have been proposed to be one of the driving forces behind the accumulation of high autoantibodies.

What immune cell type is the product of germinal centers and most likely the cell mediating the production of autoantibodies?

Possible Answers:

Natural killer cells

Tingible body macrophages

Follicular dendritic cells

Plasma cells

Follicular helper T cells

Correct answer:

Plasma cells

Explanation:

Plasma cells are the main product of germinal centers and are potent antibody factories. Dysregulated peripheral tolerance and germinal centers can lead to the production of plasma cells that are reactive towards self-nuclear antigens.

Example Question #58 : Immune System

Which of the following is an example of a primary lymphoid organ?

Possible Answers:

Lymph nodes

Spleen

Peyer's patches

Thymus

Tonsils

Correct answer:

Thymus

Explanation:

The thymus is a primary lymphoid organ (along with bone marrow). The thymus is where T cells differentiate and mature. All of the other organs listed are secondary lymphoid organs, where lymphocytes reside and respond to antigenic challenges and foreign pathogens.

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