This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
The rate-limiting enzyme in glycolysis is 
Select and explain. 
A. Glucose 6-dehydrogenase, B. Phosphofructokinase, C. Glucokinase, D. Pyruvate kinase
B: Phosphofructokinase
Answer: B: Phosphofructokinase 
Explanation: Phosphofructokinase (PFK)(step3) is the most impoant rate-limiting enzyme for glycolysis pathway. Step 3The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form fructose 1, 6-bisphosphate.Fructose 6-phosphate (C6H11O6P1) + phosphofructokinase + ATP - ADP + Fructose 1, 6-bisphosphate (C6H10O6P2) Ref: DM Vasudevan, 7th edition, page no: 113