Senior 3 Biology Notes: Gaseous Exchange, Excretion and Osmoregulation

This is a long set of Senior 3 Biology notes. It starts with gaseous exchange in mammals: the air passages, the alveoli, how breathing in and out works, and how air changes between inhaling and exhaling. It describes classroom experiments, such as the bell jar lung model and the lime water test for carbon dioxide. It then covers excretion and osmoregulation. It compares ammonia, urea and uric acid as waste products, lists the excretory organs, and explains the human urinary system, the structure of the kidney and nephron, ultrafiltration and selective reabsorption. Tables and step-by-step explanations make the notes useful for lessons and revision.