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: Unknown
The enzyme not involved in substrate level phosphorylation is: 
Select and explain. 
A. Succinyl thiokinase, B. Phosphofructokinase, C. Pyruvate kinase, D. Phosphoglycerate kinase
B: Phosphofructokinase
Answer: B: Phosphofructokinase 
Explanation: (Refer: Harper’s Illustrated Biochemistry, 27th edition, pg no: 172 – 185)
Oxidative phosphorylation

The energy released as a result of biological oxidation is trapped in the form of higher energy phosphate bonds in ATP by phosphorylation of ADP.