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
Reducing agent used in lipogenesis is derived from 
Select and explain. 
A. Pentose phosphate pathway, B. Glycolysis, C. TCA cycle, D. Gluconeogenesis
A: Pentose phosphate pathway
Answer: A: Pentose phosphate pathway 
Explanation: NADPH is involved as donor of reducing equivalents in both the reduction of the 3-ketoacyl and of the 2, 3-unsaturated acyl derivatives. The oxidative reactions of the pentose phosphate are the chief source of the hydrogen required for the reductive synthesis of fatty acids.