Write the functions of different components of blood.
1. Red blood cells (RBC) - contain the iron-rich protein called haemoglobin. Their main function is to transport oxygen from and to various tissues and organs.
2. White blood cells (WBC) - They are colourless because they do not possess haemoglobin. WBCs mainly contribute to immunity and defence mechanism.
3. Platelets - Platelets come into play when there is a wound or bleeding. They help in clotting and coagulation of blood. Platelets help in coagulation during a cut or wound.