NY01 Version 2 Practice Test

Adaptive immunity is the targeted, learned defense that recognizes specific pathogens and remembers them for faster responses in the future. The cells that carry out this precise defense are specialized T cells. When they become cytotoxic T lymphocytes, they directly kill infected cells by recognizing specific antigens presented on MHC class I molecules. This cell-mediated response is a hallmark of adaptive immunity because it is antigen-specific and capable of memory.

The other options belong to innate or non-targeted responses. The membrane attack complex from the complement system is a rapid, nonspecific defense. Phagocytosis by neutrophils is an innate, first-line process. IgE-mediated mast cell degranulation is part of adaptive responses but is tied to allergic reactions rather than the direct cytotoxic clearance of infected cells.