Question

How is urine produced? [3 MARKS]

Answer 1

Each point: 1 Mark

Urine formation takes place in following three steps:

1. All the substances from blood except blood cells are filtered by nephrons (ultrafiltration).
2. Useful substances are reabsorbed into the blood by the tubules of nephrons (selective reabsorption).
3. Some more toxic/waste material is again secreted by the tubules and the final product that leaves the kidney is called urine (tubular secretion).