GED Science Practice

What is the primary function of the kidney?

1. Regulating body temperature

2. Storing bile

3. Filtering wastes from the blood and excreting them

4. Producing red blood cells

The correct answer is: Filtering wastes from the blood and excreting them

The primary function of the kidney is to filter wastes from the blood and excrete them. This process involves the removal of waste products, such as urea and creatinine, which are generated from the breakdown of proteins and other substances in the body. The kidneys play a crucial role in maintaining the body's homeostasis by regulating the balance of electrolytes, fluids, and pH levels. They filter blood, reabsorb vital substances that the body needs, and combine the remaining waste products with excess water to form urine. This urine is then transported to the bladder for storage until it is excreted from the body. In contrast, regulating body temperature is primarily a function of the skin and mechanisms like sweating or shivering. Storing bile is a function of the gallbladder, which helps in digesting fats, while producing red blood cells is mainly the responsibility of the bone marrow, with kidneys supporting this process by producing erythropoietin, a hormone that stimulates red blood cell production when oxygen levels are low. However, the essential role of the kidneys is indeed centered around filtering blood and excreting waste products.