Biology (0610) Diseases and Immunity Revision Note

This document covers diseases and immunity for CAIE IGCSE Biology. It defines pathogens and transmissible diseases, explaining their spread through direct and indirect contact. Body defences are outlined, including mechanical barriers (skin, nasal hairs), chemical barriers (mucus, stomach acid), and white blood cells (phagocytosis and antibody production). It explains active immunity, developed through infection or vaccination, and passive immunity, gained through antibodies from another source such as breastfeeding. Vaccination is detailed as a process using weakened pathogens to stimulate memory cell production, leading to long-term immunity and herd protection. The document also introduces autoimmune diseases, where the immune system mistakenly attacks the body’s own cells. A case study of cholera is included, describing how Vibrio cholerae bacteria cause diarrhoea through toxin production, leading to dehydration, and its treatment using oral rehydration therapy and antibiotics. This guide equips students with essential knowledge of immunity, disease prevention, and treatment strategies.