Antibody
Exam-ready definition
A protein produced by lymphocytes that binds to specific antigens on a pathogen, marking it for destruction or causing pathogens to clump together.
How this is marked
The specificity idea pays: each antibody is complementary to one antigen. In immunity questions, distinguish lymphocytes (produce antibodies) from phagocytes (engulf pathogens). Mixing them up is one of the most common dropped marks in the disease topic.
In an exam answer
Explaining immunity: 'Lymphocytes produce antibodies, proteins that are complementary to the antigens on the pathogen and bind to them, marking it for destruction.'
Full topic guide: Transport in animals
Related terms