1. (i) Label the parts 1 to 4 indicated in the diagram. (Type in the parts separated by commas. Leave no spaces around the commas.)   2. (ii) Give one difference between the parts 1 and 2 based on:- (1) their structure   3. (2) the nature of blood flowing through them.   4. (iii) What is the specific name of the type of blood circulation that takes place between the heart and the lungs?   5. (iv) Name the valve found at the beginning of the part labelled 3.