On which of these does ADH act upon?

What is the normal amount of urea in the blood?

Which of the following is the first step towards urine formation?

Which of the following is called a salt retaining hormone?

Where do the juxtamedullary nephrons dip?

How is water reabsorbed in the initial segments of the nephrons?

Which of the following phyla have nephridia as an excretory structure?

Which of the following segments can allow the passage of urea through them?