Micro

Question 1

What does positive selection accomplish?

Answer 1

Determination of which become CD4 or CD8 cells

Double-positive cells (CD4+/CD8+) that interact well with MHC Class II molecules will eventually become CD4+ cells, whereas thymocytes that interact well with MHC class I molecules mature into CD8+ cells.
The process of removing thymocytes that may cause autoimmunity is negative selection.

Question 2

What is the mechanism of action of surfactants on bacteria?

Answer 2

Injury to cell membrane

Question 3

An 8 year old develops contact dermatitis from poison ivy, what most likely mediated this reaction?

Answer 3

T cells

After sensitization on initial exposure to the skin, antigen-specific T cells undergo clonal proliferation and create cells with immune memory for the antigen that generate an immune response after re-exposure to the antigen.

Question 4

Which of the following protozoa is often linked with fatty diarrhea/stools and bloating?

A. Giardia lamblia
B. Entamoeba histolytica
C. Cryptosporidium
D. Toxoplasma gondii

Answer 4

A. Giardia lamblia

Question 5

Which of the following is NOT characteristic of Bordetella pertussis?

A. IT may have secondary complications such as pneumonia, encephalopathy, or seizures
B. Whooping cough
C. It grows in moist areas such as AC units and water cooling towers.
D. It is preventable with a vaccine

Answer 5

C. It grows in moist areas - This is characteristic of Legionella pneumophilia