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
Which of the following does not cross the cell membrane 
Select and explain. 
A. Glucose-6-phosphate, B. Glucose, C. Nitrous oxide, D. Carbon monoxide
A: Glucose-6-phosphate
Answer: A: Glucose-6-phosphate 
Explanation: Glucose-6-phosphate 
"Glucose-6-phosphate cannot diffuse out of muscle cells".             —Pankaj Naik

Glucose-6-phosphate cannot diffuse out of the cell as such. First, it has to be converted to glucose by glucose-6-phosphatase which then diffuse out of the cells. This occurs in liver. Thus, glucose can be used by other tissues.

Muscle cells does not contain glucose-6-phosphatase, glucose-6-phosphate cannot be converted to glucose and glucose-6-phosphate can only by utilized as a source of energy by only muscle itself.