What is the fundamental difference between innate and adaptive immunity in terms of specificity and memory?

• A. Innate immunity is non-specific and lacks memory; adaptive immunity is antigen-specific and develops memory for faster responses on re-exposure.
• B. Innate immunity involves antibodies and memory; adaptive immunity uses cells only.
• C. Innate immunity is rapid but specific; adaptive immunity is slower and non-specific.
• D. Adaptive immunity is non-specific and lacks memory; innate immunity is antigen-specific and develops memory.

Answer: (A)

The main idea tested is how innate and adaptive immunity differ in how specifically they recognize targets and whether they remember past encounters. Innate immunity provides a rapid, broad defense that recognizes general features shared by many pathogens through pattern-recognition receptors; it does not create lasting memory of past infections. In contrast, adaptive immunity uses highly specific receptors on B and T cells, each trained to recognize a particular antigen, and it forms memory cells after an encounter. This means it responds more quickly and robustly if the same antigen is encountered again.

That’s why the best choice states that innate immunity is non-specific and lacks memory, while adaptive immunity is antigen-specific and develops memory for faster responses on re-exposure. The other options mix up these ideas—for example, antibodies and memory are hallmarks of adaptive immunity, not innate; and adaptive immunity is not slower and non-specific.