This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Riboflavin is a constituent of ? 
Select and explain. 
A. FMN, B. NAD, C. PLP, D. THF
A: FMN
Answer: A: FMN 
Explanation: Ans. is 'a' i.e., FMN Riboflavin is also called Warburg yellow enzyme. Riboflavin provides the reactive moieties of the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Flavin coenzymes are involved in oxidoreduction reactions as electron carriers. These reactions include the mitochondrial respiratory chain, key enzymes in fatty acid and amino acid oxidation and the citric acid cycle.