1. (i) Name the parts labelled 1, 2, 4 and 6.   2. (ii) Give the number and name of vessel which contains the maximum amount of urea a few hours after a protein rich meal.   3. (iii) Draw a neat, labelled diagram of the cross-sectional view of the blood vessel numbered 3.   4. (iv) Mention two structural difference between blood vessels '3' and '8'.