1. Six current focused system routes
Unit 5 explicitly covers six current system topics, each owned in depth by its own focused route.
Unit 5: Human Physiology is an exact current official Biology unit in the verified 2026 syllabus. Its explicit current topic clusters are breathing/respiration, body fluids/circulation, excretory products, locomotion/movement, neural control and chemical coordination. This page shows the dependency logic between them rather than duplicating a summary of every child page.
