In a coloured diagram, why do we generally show the pulmonary artery in blue and pulmonary vein in red colour ?

Name any four substances transported by blood.

Name the following :

(i) The yellow coloured fluid part of the blood.

(ii) The respiratory pigment contained in RBCs.

(iii) Any two organelles absent in mature RBCs.

(iv) The process of WBCs squeezing out through the walls of the blood capillaries.

Mention the following:

(i) Average life span of RBCs.

(ii) Range of RBCs per mm³ in a normal adult human female.

(iii) The two major categories of WBCs.

(iv) Blood cells involved in leukaemia.