Final answer:
Glucose is the only molecule mentioned that is fully reabsorbed in the kidneys. Water, sodium ions, and urea undergo partial reabsorption or are excreted as waste products.
Step-by-step explanation:
Glucose, water, sodium ions, and urea are all filtered out of the blood in one part of the kidney and then reabsorbed in another part. However, only glucose is completely reabsorbed and none of it is excreted in the urine.
This is because there are a finite number of carrier proteins for glucose, so if more glucose is present than the proteins can handle, the excess is not transported and is excreted from the body in the urine. The other substances mentioned, such as water, sodium ions, and urea, undergo partial reabsorption or are excreted as waste products.