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
The binding of epinephrine or glucagon to the corresponding membrane receptor has which of the following effects on glycogen metabolism? 
Select and explain. 
A. The net synthesis of glycogen is increased., B. Glycogen phosphorylase is activated, while glycogen synthase is inactivated., C. Glycogen phosphorylase is inactivated, while glycogen synthase is activated., D. Both glycogen synthase and phosphorylase are activated.
B: Glycogen phosphorylase is activated, while glycogen synthase is inactivated.
Answer: B: Glycogen phosphorylase is activated, while glycogen synthase is inactivated. 
Explanation: Both epinephrine and glucagons result in activities which serve to increase (maintain) blood glucose. Activation of glycogen phosphorylase will result in glycogen degradation, ultimately providing a source of glucose. Glycogen synthase inhibition results in decreased synthesis of glycogen.