Antibody

In the syllabus and the exam

Antibody is examined as the specific defensive protein produced by white blood cells, and SPM questions push candidates beyond the basic definition towards the idea of specificity, in which one antibody shape fits only one matching antigen shape, much like a lock and key. Candidates need to describe how an antibody works, for example by binding to a pathogen to mark it for destruction, causing pathogens to clump together, or neutralising toxins, and to link antibody production to the concept of active immunity, where the body makes its own antibodies after infection or vaccination. Graph-based questions are common in this topic, showing antibody concentration over time after a first and second exposure, and candidates are expected to read off and explain the faster, larger secondary response caused by memory cells. A frequent error is describing antibodies as effective against all pathogens rather than only the specific antigen that triggered their production.

Example

Antibodies produced against chickenpox remain in the blood for years, which is why most people catch chickenpox only once.

Related terms

AntigenImmunityVaccine

Source:SRC-DSKP-EN