Given alongside is a diagram of human heart showing its internal structure. Label the parts marked 1 to 5, and answer the following questions.

(a) Which type of blood is carried by the blood vessel marked 2?

(b) Name the main artery which takes the blood from heart to different parts of the body?

(c) Which chamber of the heart receives oxygenated blood from the lungs?

Distinguish between arteries and veins on the basis of their structure.

Distinguish between Blood groups 'AB' and 'O' on the basis of antigens.

Distinguish between pulmonary and systemic circulation on the basis of direction of blood flow.