The sum of the attractive and repulsive forces of all antibodies binding to an antigen is:

Correct Answer: A

Rationale: Affinity is binding strength; avidity is total strength, cross-reactivity is nonspecific binding, and non-reactivity is lack of binding.

Correct Answer: B

Rationale: Peyer's patches are in the small intestine; tonsils are in the throat, appendix is separate, and spleen is abdominal.

Correct Answer: B

Rationale: The spleen removes damaged RBCs; thymus matures T cells, nodes filter lymph, appendix is minor.

Correct Answer: B

Rationale: The spleen filters blood and stores platelets; thymus matures T cells, nodes filter lymph, tonsils trap pathogens.

Correct Answer: D

Rationale: Dendritic cells trap antigens; lymphocytes respond, macrophages phagocytose, neutrophils are blood-based.