Excretion and Homeostasis – Senior 3 Biology Notes

These Senior 3 Biology notes cover excretion and homeostasis. They start by defining excretion, osmoregulation, secretion and homeostasis. Next they describe how waste is removed in protozoa and in plants, and list plant waste products that are useful to people. The notes then compare nitrogenous and non-nitrogenous wastes across animal groups and their habitats. Most of the content is on the human urinary system: the structure of the kidney, the parts of the nephron and how each part is adapted to its job, ultrafiltration, selective reabsorption, and how blood and urine differ in composition. The notes end with osmoregulation, explaining how ADH and the hypothalamus control water balance.