1. (i) Name the parts 1, 2, 3 and 4 indicated by guidelines.   2. (ii) Mention two structural differences between the parts labelled '1' and '2'.   3. (iii) What is the main function of the parts labelled 1, 2, 3?   4. (iv) What is the life span of the part labelled '1'?   5. (v) Name a soluble protein found in '4' which helps in the clotting of blood.   6. (vi) Name the disease in which blood fails to clot naturally.