This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Galactose and fructose metabolism, Subject name: Biochemistry
Net ATPs produced by substrate level phosphorylation when one molecule of fructose is conveed to two molecules of pyruvate? 
Select and explain. 
A. 2, B. 3, C. 4, D. 5
A: 2
Answer: A: 2 
Explanation: ATP yield of fructose is same as that of glucose. One may argue that fructose enters glycolysis bypassing the energy investment step (fructose-1-phosphate to fructose 1,6 bisphosphate) and thus 1 ATP should be obtained extra. but one extra ATP is used for conversion of glyceraldehyde to GAP. So ATP consumption (total 2 per fructose) is same as glycolysis of glucose. Look at the ATP used in the image when fructose enter glycolysis. Hence Net ATP yield is also 4 ATP produced- 2 ATP used = 2 ATPs