ATI RN
PAL Histology Lymphatic System Lab Practical Question 1 Questions
Question 1 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 2 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.
Question 3 of 5
Some viruses have mechanisms to down-regulate MHC class I protein expression on the surface of cells in which the virus is replicating. This immune evasion strategy might prevent effector CD8 cytotoxic T cells from recognizing and killing the virus-infected cells. Would this immune evasion strategy also prevent the initial activation of virus-specific CD8 T cells?
Correct Answer: B
Rationale: DCs cross-present viral peptides , bypassing evasion; not all cells (A, D) or early presentation explain activation.
Question 4 of 5
Vibrations from the sound waves are amplified by
Correct Answer: C
Rationale: The stirrup (stapes) in the middle ear amplifies sound vibrations, while the eardrum transmits and the anvil (incus) transfers them, but amplification is primarily by the stapes.
Question 5 of 5
Which of the following statements regarding antigens and antibodies is false?
Correct Answer: D
Rationale: Antibodies have two antigen-binding sites, not one, making D false; the others are true about antigen-antibody interactions.