CSIR-NET Dec-2015 Q1

The biological functions of the cytochrome P₄₅₀ and myoglobin are, respectively 
(1.) Oxidation of alkene and O₂ storage 
(2.) O₂ transport and O₂ storage 
(3.) O2 storage and electron carrier 
(4.) Electron carrier and O₂ transport 

Soln 
(1) Oxidation of alkene (aliphatic)
The most common reaction catalyzed by cytochromes P₄₅₀ is a monooxygenase reaction, e.g., insertion of one atom of oxygen into the aliphatic position of an organic substrate (RH) while the other oxygen atom is reduced to water:

RH + O₂ + NADPH + H+ → ROH + H2O + NADP+

(Retrieved from https://en.wikipedia.org/wiki/Cytochrome_P450)

(2) O_{2 storage}
Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells.
Nelson DL, Cox MM (2000). Lehninger Principles of Biochemistry (3rd ed.). New York: Worth Publishers. p. 206.ISBN 0-7167-6203-X. (Google books link is the 2008 edition)