ATI RN
PAL Histology Lymphatic System Lab Practical Question 1 Questions
Question 1 of 5
Which complement protein forms a complex that functions as a chain saw to slice other C3 proteins?
Correct Answer: B
Rationale: C3bBb (convertase) cleaves C3 into C3a and C3b ; C1 initiates classical, C3 is cleaved, C4 is upstream.
Question 2 of 5
Which cells in the thymus examine T cells for MHC restriction and tolerance of self during positive selection?
Correct Answer: C
Rationale: Cortical thymic epithelial cells test T cells for MHC restriction in positive selection ; medullary cells handle negative selection.
Question 3 of 5
Which type of immunoglobulin molecule is passed on to nursing infants in breast milk?
Correct Answer: C
Rationale: IgA is in breast milk for infant gut immunity; IgG crosses the placenta, IgM and IgE don't transfer via milk.
Question 4 of 5
An infant with recurrent bacterial and fungal infections is suspected to have an immunodeficiency disease. Within two days after exposure to a pathogen, the organisms have proliferated to dangerous levels requiring immediate systemic antibiotic treatment. It is unlikely that this infant has a defect in B or T lymphocyte responses to the infection because:
Correct Answer: D
Rationale: Adaptive responses (B/T cells) take days, so rapid failure suggests innate defects; bacteria/fungi need adaptive immunity , transport occurs , spleen aids but isn't sole .
Question 5 of 5
Dendritic cells in the skin, known as Langerhans cells, express very high levels of the NOD-like receptor, NLRP3. Previous studies showed that treatment of these cells with the Staphylococcus aureus pore-forming toxin causes K⺠efflux from the cells. The explanation for these results is:
Correct Answer: C
Rationale: Live S. aureus activates TLR and NLRP3 for IL-1; toxin alone (K⺠efflux) needs a second signal, membranes lack full stimuli.