A Level Biology Practice Exam

Which type of immunity is characterized by the immune system 'remembering' an antigen?

1. Passive immunity

2. Non-specific immunity

3. Specific immunity

4. Innate immunity

The correct answer is: Specific immunity

Specific immunity is characterized by the immune system's ability to 'remember' antigens after an initial exposure. This process involves the activation of lymphocytes, particularly B cells and T cells, which are designed to recognize and respond to specific pathogens. Upon first exposure to an antigen, the immune system mounts a primary response, during which memory cells are formed. If the same pathogen invades again, these memory cells enable a much quicker and more robust secondary response, effectively 'remembering' the antigen and leading to a heightened immune response. This 'memory' aspect is crucial for the effectiveness of vaccinations, which expose the immune system to a harmless form of an antigen, allowing it to prepare for future encounters with the actual pathogen. In contrast, other forms of immunity such as passive immunity do not involve the immune system's memory but rather acquire antibodies from another source. Non-specific immunity acts as a general defense mechanism without targeting specific pathogens, and innate immunity provides immediate but non-specific responses to pathogens without memory formation. Thus, the defining feature of specific immunity is indeed its capacity for immunological memory.