Discuss the role of coordination compounds in: (a) Analytical Chemistry (b) Biological System

biological system
(1)photosynthesis occur with the help of chlorophyll pigment contains magnesium
(2)the oxygen carrier of blood is a haemoglobin is a cordination compound of iron

analytical system
during salt analysis a number of basic radical are detected with the help of colour changes they exhibit with different reagent.these colour changes are the result of result of coordination compound that the basic radical form with different regent